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  • How can I split a LINESTRING into two LINESTRINGs at a given point?

    - by sabbour
    Hello, I'm trying to write a function that will split a LINESTRING into two LINESTRINGs given the split point. What I'm trying to achieve is a function that given a LINESTRING and a distance, it will return N LINESTRINGS for the original linestring splitted at multiples of that distance. This is what I have so far (I'm using SQL Server Spatial Tools from CodePlex): DECLARE @testLine geography; DECLARE @slicePoint geography; SET @testLine = geography::STGeomFromText('LINESTRING (34.5157942 28.5039665, 34.5157079 28.504725, 34.5156881 28.5049565, 34.5156773 28.505082, 34.5155642 28.5054437, 34.5155498 28.5054899, 34.5154937 28.5058826, 34.5154643 28.5060218, 34.5153968 28.5063415, 34.5153322 28.5065338, 34.5152031 28.5069178, 34.5150603 28.5072288, 34.5148716 28.5075501, 34.5146106 28.5079974, 34.5143617 28.5083813, 34.5141373 28.5086414, 34.5139954 28.5088441, 34.5138874 28.5089983, 34.5138311 28.5091054, 34.5136783 28.5093961, 34.5134336 28.5097531, 34.51325 28.5100794, 34.5130256 28.5105078, 34.5128754 28.5107957, 34.5126258 28.5113222, 34.5123984 28.5117673)', 4326) DECLARE @pointOne geography; declare @result table (segment geography) DECLARE @sliceDistance float DECLARE @nextSliceAt float SET @sliceDistance = 100 -- slice every 100 meters SET @nextSliceAt = @sliceDistance SELECT @pointOne = @testLine.STStartPoint() WHILE(@nextSliceAt < @testLine.STLength()) BEGIN SELECT @slicePoint = dbo.LocateAlongGeog(@testLine,@nextSliceAt) DECLARE @subLineString geography; SET @subLineString = geography::STGeomFromText('LINESTRING (' + dbo.FloatToVarchar(@pointOne.Long) + ' ' + dbo.FloatToVarchar(@pointOne.Lat) + ',' + dbo.FloatToVarchar(@slicePoint.Long) + ' ' + dbo.FloatToVarchar(@slicePoint.Lat) +')', 4326) insert into @result SELECT @subLineString SET @pointOne = @slicePoint set @nextSliceAt = @nextSliceAt + @sliceDistance END SET @subLineString = geography::STGeomFromText('LINESTRING (' + dbo.FloatToVarchar(@pointOne.Long) + ' ' + dbo.FloatToVarchar(@pointOne.Lat) + ',' + dbo.FloatToVarchar(@testLine.STEndPoint().Long) + ' ' + dbo.FloatToVarchar(@testLine.STEndPoint().Lat) +')', 4326) insert into @result SELECT @subLineString select * from @result I know it is not the best looking code, but there is another problem. The above code approximates the resulting LINESTRING because it does not follow the curvature of the original LINESTRING as it only takes into consideration the start and end points when creating the new segment. Is there a way take a substring out of the original LINESTRING given the start and end points?

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  • Recursive templates: compilation error under g++

    - by Johannes
    Hi, I am trying to use templates recursively to define (at compile-time) a d-tuple of doubles. The code below compiles fine with Visual Studio 2010, but g++ fails and complains that it "cannot call constructor 'point<1::point' directly". Could anyone please shed some light on what is going on here? Many thanks, Jo #include <iostream> #include <utility> using namespace std; template <const int N> class point { private: pair<double, point<N-1> > coordPointPair; public: point() { coordPointPair.first = 0; coordPointPair.second.point<N-1>::point(); } }; template<> class point<1> { private: double coord; public: point() { coord= 0; } }; int main() { point<5> myPoint; return 0; }

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  • Storing and retrieving CGPoints inside NSMutableArray

    - by Matt Dice
    I've looked through countless questions on here and elsewhere and cannot for the life of me figure out what I'm doing wrong. I'm trying to store an array of CGPoints as NSValues inside of an NSMutableArray named points like so on the iPhone: NSValue *point = [NSValue valueWithCGPoint:firstTouch]; NSLog(@"NSValue *point = %@", point); [points addObject:point]; NSLOG OUTPUT NSValue *point = NSPoint: {120, 221} Everything is going smooth converting from the CGPoint to NSValue. But when I try to retrieve the point I get nothing. NSValue *getPoint = [points objectAtIndex:0]; CGPoint thePoint = [getPoint CGPointValue]; NSLog(@"Point = %@", NSStringFromCGPoint(thePoint)); NSLOG OUTPUT Point = {0, 0} The points should be the same but I'm getting a null result. For testing purposes this is happening in the touchesBegan method. Does anyone have any idea where I'm going wrong? Thanks in advance.

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  • Is there any point in using a volatile long?

    - by Adamski
    I occasionally use a volatile instance variable in cases where I have two threads reading from / writing to it and don't want the overhead (or potential deadlock risk) of taking out a lock; for example a timer thread periodically updating an int ID that is exposed as a getter on some class: public class MyClass { private volatile int id; public MyClass() { ScheduledExecutorService execService = Executors.newScheduledThreadPool(1); execService.scheduleAtFixedRate(new Runnable() { public void run() { ++id; } }, 0L, 30L, TimeUnit.SECONDS); } public int getId() { return id; } } My question: Given that the JLS only guarantees that 32-bit reads will be atomic is there any point in ever using a volatile long? (i.e. 64-bit). Caveat: Please do not reply saying that using volatile over synchronized is a case of pre-optimisation; I am well aware of how / when to use synchronized but there are cases where volatile is preferable. For example, when defining a Spring bean for use in a single-threaded application I tend to favour volatile instance variables, as there is no guarantee that the Spring context will initialise each bean's properties in the main thread.

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  • Reverse-projection 2D points into 3D

    - by ehsan baghaki
    Suppose we have a 3d Space with a plane on it with an arbitary equation : ax+by+cz+d=0 now suppose that we pick 3 random points on that plane: (x0,y0,z0) (x1,y1,z1) (x1,y1,z1) now i have a different point of view(camera) for this plane. i mean i have a different camera that will look at this plane from a different point of view. From that camera point of view these points have different locations. for example (x0,y0,z0) will be (x0',y0') and (x1,y1,z1) will be (x1',y1') and (x2,y2,z2) will be (x2',y2') from the new camera point of view. So here is my a little hard question! I want to pick a point for example (X,Y) from the new camera point of view and tell where it will be on that plane. All i know is that 3 points and their locations on 3d space and their projection locations on the new camera view. Do you know the coefficients of the plane-equation and the camera positions (along with the projection), or do you only have the six points? - Nils i know the location of first 3 points. therefore we can calculate the coefficients of the plane. so we know exactly where the plane is from (0,0,0) point of view. and then we have the camera that can only see the points! So the only thing that camera sees is 3 points and also it knows their locations in 3d space (and for sure their locations on 2d camera view plane). and after all i want to look at camera view, pick a point (for example (x1,y1)) and tell where is that point on that plane. (for sure this (X,Y,Z) point should fit on the plane equation). Also i know nothing about the camera location.

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  • Why does Perl's Devel::LeakTrace::Fast point to blank files and evals?

    - by kt
    I am using Devel::LeakTrace::Fast to debug a memory leak in a perl script designed as a daemon which runs an infinite loop with sleeps until interrupted. I am having some trouble both reading the output and finding documentation to help me understand the output. The perldoc doesn't contain much information on the output. Most of it makes sense, such as pointing to globals in DBI. Intermingled with the output, however, are several leaked SV(<LOCATION>) from (eval #) line # Where the numbers are numbers and <LOCATION> is a location in memory. The script itself is not using eval at any point - I have not investigated each used module to see if evals are present. Mostly what I want to know is how to find these evals (if possible). I also find the following entries repeated over and over again leaked SV(<LOCATION>) from line # Where line # is always the same #. Not very helpful in tracking down what file that line is in.

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  • iPhone SDK: How to center map around a particular point?

    - by buzzappsoftware
    New to MapKit. Having problems centering map around a specified point. Here is the code. Not sure why this is not working. We are expecting to see a map centered around Cincinnati, OH. What we are seeing is the default google map of the world. Any help appreciated. / Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; CLLocationCoordinate2D mapCoords[2]; mapCoords[0].latitude = 39.144057; mapCoords[0].latitude = -84.505484; mapCoords[1].latitude = 39.142984; mapCoords[1].latitude = -84.502534; MKCoordinateSpan span; span.latitudeDelta = 0.2; span.longitudeDelta = 0.2; MKCoordinateRegion region; region.center = mapCoords[0]; region.span = span; [mapView setRegion:region animated:YES]; }

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  • What's the point of indicating AllowMultiple=false on an abstract Attribute class?

    - by tvanfosson
    On a recent question about MVC attributes, someone asked whether using HttpPost and HttpDelete attributes on an action method would result in either request type being allowed or no requests being allowed (since it can't be both a Post and a Delete at the same time). I noticed that ActionMethodSelectorAttribute, from which HttpPostAttribute and HttpDeleteAttribute both derive is decorated with [AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = true)] I had expected it to not allow both HttpPost and HttpDelete on the same method because of this, but the compiler doesn't complain. My limited testing tells me that the attribute usage on the base class is simply ignored. AllowMultiple seemingly only disallows two of the same attribute from being applied to a method/class and doesn't seem to consider whether those attributes derive from the same class which is configured to not allow multiples. Moreover, the attribute usage on the base class doesn't even preclude your from changing the attribute usage on a derived class. That being the case, what's the point of even setting the values on the base attribute class? Is it just advisory or am I missing something fundamental in how they work? FYI - it turns out that using both basically precludes that method from ever being considered. The attributes are evaluated independently and one of them will always indicate that the method is not valid for the request since it can't simultaneously be both a Post and a Delete.

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  • Confusion about pointers and their memory addresses

    - by TimothyTech
    alright, im looking at a code here and the idea is difficult to understand. #include <iostream> using namespace std; class Point { public : int X,Y; Point() : X(0), Y(0) {} }; void MoveUp (Point * p) { p -> Y += 5; } int main() { Point point MoveUp(&point) cout <<point.X << point.Y; return 0; } Alright, so i believe that a class is created and X and Y are declared and they are put inside a constructor a method is created and the argument is Point * p, which means that we are going to stick the constructor's pointer inside the function; now we create an object called point then call our method and put the pointers address inside it? isnt the pointers address just a memory number like 0x255255? and why wasnt p ever declared? (int * p = Y) what is a memory addres exactly? that it can be used as an argument?

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  • What is the point of having a key_t if what will be the key to access shared memory is the return value of shmget()?

    - by devoured elysium
    When using shared memory, why should we care about creating a key key_t ftok(const char *path, int id); in the following bit of code? key_t key; int shmid; key = ftok("/home/beej/somefile3", 'R'); shmid = shmget(key, 1024, 0644 | IPC_CREAT); From what I've come to understand, what is needed to access a given shared memory is the shmid, not the key. Or am I wrong? If what we need is the shmid, what is the point in not just creating a random key every time? Edit @link text one can read: What about this key nonsense? How do we create one? Well, since the type key_t is actually just a long, you can use any number you want. But what if you hard-code the number and some other unrelated program hardcodes the same number but wants another queue? The solution is to use the ftok() function which generates a key from two arguments. Reading this, it gives me the impression that what one needs to attach to a shared-memory block is the key. But this isn't true, is it? Thanks

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  • Is there a point to have multiple VS projects for an ASP.NET MVC application?

    - by mare
    I'm developing MVC application where I currently have 3 projects in solution. Core (it is supposed to be for Repositories, Business Classes, Models, HttpModules, HttpFilters, Settings, etc.) Data access (Data provider, for instance SqlDataProvider for working with SQL Server datastore - implements Repository interfaces, XmlDataProvider - also implements Repository interfaces but for local XML files as datastore) ASP.NET MVC project (all the typical stuff, UI, controllers, content, scripts, resources and helpers). I have no Models in my ASP.NET MVC project. I've just run into a problem because of that coz I want to use the new DataAnnotation feature in MVC 2 on my Bussiness class, which are, as said in Core, however I have I want to be able to localize the error messages. This where my problem starts. I cannot use my Resources from MVC project in Core. The MVC project references Core and it cannot be vice-versa. My options as I see them are: 1) Move Resources out but this would require correcting a whole bunch of Views and Controllers where I reference them, 2) Make a complete restructure of my app What are your thoughts on this? Also, Should I just move everything business related into Models folder in MVC project?? Does it even make any sense to have it structured like that, because we can just make subfolders for everything under MVC project? The whole Core library is not intended to ever be used for anything else, so there actually no point of compiling it to a separate DLL. Suggestions appreciated.

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  • determine if line segment is inside polygon

    - by dato
    suppose we have simple polygon(without holes) with vertices (v0,v1,....vn) my aim is to determine if for given point p(x,y) any line segment connecting this point and any vertices of polygon is inside polygon or even for given two point p(x0,y0) `p(x1,y1)` line segment connecting these two point is inside polygon? i have searched many sites about this ,but i am still confused,generally i think we have to compare coordinates of vertices and by determing coordinates of which point is less or greater to another point's coordinates,we could determine location of any line segment,but i am not sure how correct is this,please help me

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  • Wireless cuts out on Toshiba Satellite S7208

    - by alecRN
    I recently got a Toshiba Satellite L875-S7208 with Windows 7 preinstalled. I installed Ubuntu 12.04 LTS dual boot to the same Windows partition. However, usually 15 minutes or less after booting, the wifi connection dies. Here's some hopefully relevant information: lspci -knn 00:00.0 Host bridge [0600]: Intel Corporation 2nd Generation Core Processor Family DRAM Controller [8086:0104] (rev 09) Subsystem: Toshiba America Info Systems Device [1179:fb41] Kernel driver in use: agpgart-intel 00:02.0 VGA compatible controller [0300]: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09) Subsystem: Toshiba America Info Systems Device [1179:fb40] Kernel driver in use: i915 Kernel modules: i915 00:14.0 USB controller [0c03]: Intel Corporation Panther Point USB xHCI Host Controller [8086:1e31] (rev 04) Subsystem: Toshiba America Info Systems Device [1179:fb41] Kernel driver in use: xhci_hcd 00:16.0 Communication controller [0780]: Intel Corporation Panther Point MEI Controller #1 [8086:1e3a] (rev 04) Subsystem: Toshiba America Info Systems Device [1179:fb41] Kernel driver in use: mei Kernel modules: mei 00:1a.0 USB controller [0c03]: Intel Corporation Panther Point USB Enhanced Host Controller #2 [8086:1e2d] (rev 04) Subsystem: Toshiba America Info Systems Device [1179:fb41] Kernel driver in use: ehci_hcd 00:1b.0 Audio device [0403]: Intel Corporation Panther Point High Definition Audio Controller [8086:1e20] (rev 04) Subsystem: Toshiba America Info Systems Device [1179:fb40] Kernel driver in use: snd_hda_intel Kernel modules: snd-hda-intel 00:1c.0 PCI bridge [0604]: Intel Corporation Panther Point PCI Express Root Port 1 [8086:1e10] (rev c4) Kernel driver in use: pcieport Kernel modules: shpchp 00:1c.1 PCI bridge [0604]: Intel Corporation Panther Point PCI Express Root Port 2 [8086:1e12] (rev c4) Kernel driver in use: pcieport Kernel modules: shpchp 00:1c.2 PCI bridge [0604]: Intel Corporation Panther Point PCI Express Root Port 3 [8086:1e14] (rev c4) Kernel driver in use: pcieport Kernel modules: shpchp 00:1d.0 USB controller [0c03]: Intel Corporation Panther Point USB Enhanced Host Controller #1 [8086:1e26] (rev 04) Subsystem: Toshiba America Info Systems Device [1179:fb41] Kernel driver in use: ehci_hcd 00:1f.0 ISA bridge [0601]: Intel Corporation Panther Point LPC Controller [8086:1e59] (rev 04) Subsystem: Toshiba America Info Systems Device [1179:fb41] Kernel modules: iTCO_wdt 00:1f.2 SATA controller [0106]: Intel Corporation Panther Point 6 port SATA Controller [AHCI mode] [8086:1e03] (rev 04) Subsystem: Toshiba America Info Systems Device [1179:fb41] Kernel driver in use: ahci 00:1f.3 SMBus [0c05]: Intel Corporation Panther Point SMBus Controller [8086:1e22] (rev 04) Subsystem: Toshiba America Info Systems Device [1179:fb41] Kernel modules: i2c-i801 02:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. RTL8188CE 802.11b/g/n WiFi Adapter [10ec:8176] (rev 01) Subsystem: Realtek Semiconductor Co., Ltd. Device [10ec:8211] Kernel driver in use: rtl8192ce Kernel modules: rtl8192ce 03:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller [10ec:8136] (rev 05) Subsystem: Toshiba America Info Systems Device [1179:fb37] Kernel driver in use: r8169 Kernel modules: r8169 lsmod Module Size Used by snd_hda_codec_hdmi 32474 1 snd_hda_codec_realtek 224066 1 joydev 17693 0 rfcomm 47604 0 bnep 18281 2 bluetooth 180104 10 rfcomm,bnep parport_pc 32866 0 ppdev 17113 0 arc4 12529 2 snd_hda_intel 33773 3 snd_hda_codec 127706 3 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel snd_hwdep 13668 1 snd_hda_codec snd_pcm 97188 3 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec snd_seq_midi 13324 0 snd_rawmidi 30748 1 snd_seq_midi snd_seq_midi_event 14899 1 snd_seq_midi snd_seq 61896 2 snd_seq_midi,snd_seq_midi_event snd_timer 29990 2 snd_pcm,snd_seq snd_seq_device 14540 3 snd_seq_midi,snd_rawmidi,snd_seq psmouse 87692 0 serio_raw 13211 0 rtl8192ce 84826 0 rtl8192c_common 75767 1 rtl8192ce rtlwifi 111202 1 rtl8192ce mac80211 506816 3 rtl8192ce,rtl8192c_common,rtlwifi snd 78855 16 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_rawmidi,snd_seq,snd_timer,snd_seq_device sparse_keymap 13890 0 uvcvideo 72627 0 videodev 98259 1 uvcvideo v4l2_compat_ioctl32 17128 1 videodev mac_hid 13253 0 mei 41616 0 wmi 19256 0 soundcore 15091 1 snd i915 472941 3 snd_page_alloc 18529 2 snd_hda_intel,snd_pcm drm_kms_helper 46978 1 i915 cfg80211 205544 2 rtlwifi,mac80211 drm 242038 4 i915,drm_kms_helper i2c_algo_bit 13423 1 i915 video 19596 1 i915 lp 17799 0 parport 46562 3 parport_pc,ppdev,lp r8169 62099 0 ums_realtek 18248 0 uas 18180 0 usb_storage 49198 1 ums_realtek dmesg | grep firmware [ 15.692951] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 16.240881] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 452.419288] rtl8192c_common:rtl92c_firmware_selfreset(): 8051 reset fail. [ 458.572211] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 465.440640] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 472.337617] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 479.175471] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 485.978582] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 492.764893] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 499.579348] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 506.386934] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 513.209545] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 519.991365] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 526.778375] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 533.629695] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 540.426004] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 547.238125] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 554.024434] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 560.854794] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 567.678160] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 574.494666] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 581.336653] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 588.157710] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 595.221122] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 602.047429] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 608.829534] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 615.639079] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 622.454991] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 629.273231] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 636.056613] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 642.858096] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 649.640753] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 657.184094] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 664.008018] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 670.838639] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 677.675418] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 684.507255] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 691.310994] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 698.095325] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 704.914509] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin [ 711.725178] rtl8192c_common: Loading firmware file rtlwifi/rtl8192cfw.bin uname -r 3.2.0-29-generic ifconfig eth0 Link encap:Ethernet HWaddr 4c:72:b9:59:6c:61 inet addr:192.168.0.11 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::4e72:b9ff:fe59:6c61/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:4447 errors:0 dropped:0 overruns:0 frame:0 TX packets:2762 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:3671147 (3.6 MB) TX bytes:335133 (335.1 KB) Interrupt:42 Base address:0x2000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:515 errors:0 dropped:0 overruns:0 frame:0 TX packets:515 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:83153 (83.1 KB) TX bytes:83153 (83.1 KB) wlan0 Link encap:Ethernet HWaddr 74:e5:43:32:47:95 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:280 errors:0 dropped:0 overruns:0 frame:0 TX packets:51 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:32958 (32.9 KB) TX bytes:10431 (10.4 KB)

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  • How do I turn on wireless adapter on HP Envy dv6 7200 under Ubuntu (any version)?

    - by Dave B.
    I have a new HP Envy dv6 7200 with dual boot Windows 8 / Ubuntu 12.04. In windows, the F12 key in Windows activates the "airplane mode" switch which enables/disables both on-board (mini PCIe) and USB wireless adapters. In Ubuntu, however, the wireless adapter is turned off by default and cannot be turned back on via the F12 key (or any other combination of F12 and Ctrl, Fn, Shift, etc.). Let me explain the "fixes" I've seen in various forums and explain what did or did not happen. These are listed in no particular order. (Spoiler alert: wireless is still broke). Solution 1? Use HP's "Wireless Assistant" utility to permanently activate the wireless card in Windows, then boot into Ubuntu to happily find it working. Unfortunately, this utility works in Windows 7 but not Windows 8. On the other hand, hardware drivers from HP are only available for Windows 8 for this model. Catch 22 (I could not find a comparable utility for Windows 8). Solution 2? Use a USB wireless adapter to sidestep the on-board device. I purchased such a device from thinkpenguin.com to be sure that it would be Linux-friendly. However, the wireless switch enables / disables all wireless devices including USB. So, there's my $50 donation to the nice folks at thinkpenguin.com, but still no solution. Solution 3? Following the Think Penguin folk's suggestion, modify the mini PCI express adapter following instructions here: http://www.notebookforums.com/t/225429/broken-wireless-hardware-switch-fix Tempting, but I then violate the terms of my warranty mere days after opening the box. This might be a good solution for an older machine that you want to get your geek on with, but not for a new box. Solution 4? rfkill unblock all No effect whatsoever. ubuntu@ubuntu-hp-evny:~$ rfkill unblock all ubuntu@ubuntu-hp-evny:~$ rfkill list all 0: hp-wifi: Wireless LAN Soft blocked: no Hard blocked: yes Solution 5? Re-install drivers. Done and done. Ubuntu recognizes the device - perhaps even without re-installing the drivers? - but cannot turn it on. How do I know this? In the Network Manager drop-down menu, the wireless option is blacked out and a message reads something like: "wireless network is disabled by a hardware switch". Solution 6? Identify a physical switch on the laptop and flip it. There is no such switch on this machine. In fact, walking through Best Buy yesterday, I checked and not a single new laptop PC had a physical switch on it. All of the wireless switches are either the F2 or F12 key ... I wonder if askubuntu will not be plagued by this exact issue in the near future? Additional info - lspci ubuntu@ubuntu-hp-evny:~$ lspci 00:00.0 Host bridge: Intel Corporation Ivy Bridge DRAM Controller (rev 09) 00:01.0 PCI bridge: Intel Corporation Ivy Bridge PCI Express Root Port (rev 09) 00:02.0 VGA compatible controller: Intel Corporation Ivy Bridge Graphics Controller (rev 09) 00:14.0 USB controller: Intel Corporation Panther Point USB xHCI Host Controller (rev 04) 00:16.0 Communication controller: Intel Corporation Panther Point MEI Controller #1 (rev 04) 00:1a.0 USB controller: Intel Corporation Panther Point USB Enhanced Host Controller #2 (rev 04) 00:1b.0 Audio device: Intel Corporation Panther Point High Definition Audio Controller (rev 04) 00:1c.0 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 1 (rev c4) 00:1c.2 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 3 (rev c4) 00:1c.3 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 4 (rev c4) 00:1c.5 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 6 (rev c4) 00:1d.0 USB controller: Intel Corporation Panther Point USB Enhanced Host Controller #1 (rev 04) 00:1f.0 ISA bridge: Intel Corporation Panther Point LPC Controller (rev 04) 00:1f.2 RAID bus controller: Intel Corporation 82801 Mobile SATA Controller [RAID mode] (rev 04) 00:1f.3 SMBus: Intel Corporation Panther Point SMBus Controller (rev 04) 01:00.0 VGA compatible controller: NVIDIA Corporation Device 0de9 (rev a1) 08:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. Device 5229 (rev 01) 0a:00.0 Network controller: Ralink corp. Device 539b 0b:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 07) Any suggestions would be much appreciated!

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  • C problem, left of '->' must point to class/struct/union/generic type ??

    - by Patrick
    Hello! Trying to understand why this doesn't work. I keep getting the following errors: left of '-nextNode' must point to class/struct/union/generic type (Also all the lines with a - in the function new_math_struct) Header file #ifndef MSTRUCT_H #define MSTRUCT_H #define PLUS 0 #define MINUS 1 #define DIVIDE 2 #define MULTIPLY 3 #define NUMBER 4 typedef struct math_struct { int type_of_value; int value; int sum; int is_used; struct math_struct* nextNode; } ; typedef struct math_struct* math_struct_ptr; #endif C file int get_input(math_struct_ptr* startNode) { /* character, input by the user */ char input_ch; char* input_ptr; math_struct_ptr* ptr; math_struct_ptr* previousNode; input_ptr = &input_ch; previousNode = startNode; /* as long as input is not ok */ while (1) { input_ch = get_input_character(); if (input_ch == ',') // Carrage return return 1; else if (input_ch == '.') // Illegal character return 0; if (input_ch == '+') ptr = new_math_struct(PLUS, 0); else if (input_ch == '-') ptr = new_math_struct(MINUS, 0); else if (input_ch == '/') ptr = new_math_struct(DIVIDE, 0); else if (input_ch == '*') ptr = new_math_struct(MULTIPLY, 0); else ptr = new_math_struct(NUMBER, atoi(input_ptr)); if (startNode == NULL) { startNode = previousNode = ptr; } else { previousNode->nextNode = ptr; previousNode = ptr; } } return 0; } math_struct_ptr* new_math_struct(int symbol, int value) { math_struct_ptr* ptr; ptr = (math_struct_ptr*)malloc(sizeof(math_struct_ptr)); ptr->type_of_value = symbol; ptr->value = value; ptr->sum = 0; ptr->is_used = 0; return ptr; } char get_input_character() { /* character, input by the user */ char input_ch; /* get the character */ scanf("%c", &input_ch); if (input_ch == '+' || input_ch == '-' || input_ch == '*' || input_ch == '/' || input_ch == ')') return input_ch; // A special character else if (input_ch == '\n') return ','; // A carrage return else if (input_ch < '0' || input_ch > '9') return '.'; // Not a number else return input_ch; // Number } The header for the C file just contains a reference to the struct header and the definitions of the functions. Language C.

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  • MVC SiteMap - when different nodes point to same action SiteMap.CurrentNode does not map to the correct route

    - by awrigley
    Setup: I am using ASP.NET MVC 4, with mvcSiteMapProvider to manage my menus. I have a custom menu builder that evaluates whether a node is on the current branch (ie, if the SiteMap.CurrentNode is either the CurrentNode or the CurrentNode is nested under it). The code is included below, but essentially checks the url of each node and compares it with the url of the currentnode, up through the currentnodes "family tree". The CurrentBranch is used by my custom menu builder to add a class that highlights menu items on the CurrentBranch. The Problem: My custom menu works fine, but I have found that the mvcSiteMapProvider does not seem to evaluate the url of the CurrentNode in a consistent manner: When two nodes point to the same action and are distinguished only by a parameter of the action, SiteMap.CurrentNode does not seem to use the correct route (it ignores the distinguishing parameter and defaults to the first route that that maps to the action defined in the node). Example of the Problem: In an app I have Members. A Member has a MemberStatus field that can be "Unprocessed", "Active" or "Inactive". To change the MemberStatus, I have a ProcessMemberController in an Area called Admin. The processing is done using the Process action on the ProcessMemberController. My mvcSiteMap has two nodes that BOTH map to the Process action. The only difference between them is the alternate parameter (such are my client's domain semantics), that in one case has a value of "Processed" and in the other "Unprocessed": Nodes: <mvcSiteMapNode title="Process" area="Admin" controller="ProcessMembers" action="Process" alternate="Unprocessed" /> <mvcSiteMapNode title="Change Status" area="Admin" controller="ProcessMembers" action="Process" alternate="Processed" /> Routes: The corresponding routes to these two nodes are (again, the only thing that distinguishes them is the value of the alternate parameter): context.MapRoute( "Process_New_Members", "Admin/Unprocessed/Process/{MemberId}", new { controller = "ProcessMembers", action = "Process", alternate="Unprocessed", MemberId = UrlParameter.Optional } ); context.MapRoute( "Change_Status_Old_Members", "Admin/Members/Status/Change/{MemberId}", new { controller = "ProcessMembers", action = "Process", alternate="Processed", MemberId = UrlParameter.Optional } ); What works: The Html.ActionLink helper uses the routes and produces the urls I expect: @Html.ActionLink("Process", MVC.Admin.ProcessMembers.Process(item.MemberId, "Unprocessed") // Output (alternate="Unprocessed" and item.MemberId = 12): Admin/Unprocessed/Process/12 @Html.ActionLink("Status", MVC.Admin.ProcessMembers.Process(item.MemberId, "Processed") // Output (alternate="Processed" and item.MemberId = 23): Admin/Members/Status/Change/23 In both cases the output is correct and as I expect. What doesn't work: Let's say my request involves the second option, ie, /Admin/Members/Status/Change/47, corresponding to alternate = "Processed" and a MemberId of 47. Debugging my static CurrentBranch property (see below), I find that SiteMap.CurrentNode shows: PreviousSibling: null Provider: {MvcSiteMapProvider.DefaultSiteMapProvider} ReadOnly: false ResourceKey: "" Roles: Count = 0 RootNode: {Home} Title: "Process" Url: "/Admin/Unprocessed/Process/47" Ie, for a request url of /Admin/Members/Status/Change/47, SiteMap.CurrentNode.Url evaluates to /Admin/Unprocessed/Process/47. Ie, it is ignorning the alternate parameter and using the wrong route. CurrentBranch Static Property: /// <summary> /// ReadOnly. Gets the Branch of the Site Map that holds the SiteMap.CurrentNode /// </summary> public static List<SiteMapNode> CurrentBranch { get { List<SiteMapNode> currentBranch = null; if (currentBranch == null) { SiteMapNode cn = SiteMap.CurrentNode; SiteMapNode n = cn; List<SiteMapNode> ln = new List<SiteMapNode>(); if (cn != null) { while (n != null && n.Url != SiteMap.RootNode.Url) { // I don't need to check for n.ParentNode == null // because cn != null && n != SiteMap.RootNode ln.Add(n); n = n.ParentNode; } // the while loop excludes the root node, so add it here // I could add n, that should now be equal to SiteMap.RootNode, but this is clearer ln.Add(SiteMap.RootNode); // The nodes were added in reverse order, from the CurrentNode up, so reverse them. ln.Reverse(); } currentBranch = ln; } return currentBranch; } } The Question: What am I doing wrong? The routes are interpreted by Html.ActionLlink as I expect, but are not evaluated by SiteMap.CurrentNode as I expect. In other words, in evaluating my routes, SiteMap.CurrentNode ignores the distinguishing alternate parameter.

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  • Can't get my object to point at the mouse.

    - by melignus
    I'm using a combination of SDL and OpenGL in a sort of crash course project to teach myself how this all works. I'm really only interested in OpenGL as a way to use acceleration in 2D games so I just need this to work in a 2D plane. I have been having a lot of problems today with my current issue, I would like an object to point towards the mouse while the mouse button is clicked and then of course stay pointing in that direction after the mouse is lifted. void Square::handle_input() { //If a key was pressed if( event.type == SDL_KEYDOWN ) { //Adjust the velocity switch( event.key.keysym.sym ) { case SDLK_UP: upUp = false; yVel = -1; break; case SDLK_DOWN: downUp = false; yVel = 1; break; case SDLK_LEFT: leftUp = false; xVel = -1; break; case SDLK_RIGHT: rightUp = false; xVel = 1; break; case SDLK_w: wUp = false; sAng = 1; break; case SDLK_s: sUp = false; sAng = -1; break; } } //If a key was released else if( event.type == SDL_KEYUP ) { //Adjust the velocity switch( event.key.keysym.sym ) { case SDLK_UP: upUp = true; yVel = 0; break; case SDLK_DOWN: downUp = true; yVel = 0; break; case SDLK_LEFT: leftUp = true; xVel = 0; break; case SDLK_RIGHT: rightUp = true; xVel = 0; break; case SDLK_w: wUp = true; sAng = 0; break; case SDLK_s: sUp = true; sAng = 0; break; } } //If a mouse button was pressed if( event.type == SDL_MOUSEBUTTONDOWN ) { switch ( event.type ) { case SDL_MOUSEBUTTONDOWN: mouseUp = false; mousex == event.button.x; mousey == event.button.y; break; case SDL_MOUSEBUTTONUP: mouseUp = true; break; } } } And then this is called at the end of my Object::Move call which also handles x and y translation if (!mouseUp) { xVect = mousex - x; yVect = mousey - y; radAng = atan2 ( mousey - y, mousex - x ); sAng = radAng * 180 / 3.1415926l; } Right now when I click the object turns and faces down to the bottom left but then no longer changes direction. I'd really appreciate any help I could get here. I'm guessing there might be an issue here with state versus polled events but from all the tutorials that I've been through I was pretty sure I had fixed that. I've just hit a wall and I need some advice!

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  • A Taxonomy of Numerical Methods v1

    - by JoshReuben
    Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

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  • Oracle Flashback Technologies - Overview

    - by Sridhar_R-Oracle
    Oracle Flashback Technologies - IntroductionIn his May 29th 2014 blog, my colleague Joe Meeks introduced Oracle Maximum Availability Architecture (MAA) and discussed both planned and unplanned outages. Let’s take a closer look at unplanned outages. These can be caused by physical failures (e.g., server, storage, network, file deletion, physical corruption, site failures) or by logical failures – cases where all components and files are physically available, but data is incorrect or corrupt. These logical failures are usually caused by human errors or application logic errors. This blog series focuses on these logical errors – what causes them and how to address and recover from them using Oracle Database Flashback. In this introductory blog post, I’ll provide an overview of the Oracle Database Flashback technologies and will discuss the features in detail in future blog posts. Let’s get started. We are all human beings (unless a machine is reading this), and making mistakes is a part of what we do…often what we do best!  We “fat finger”, we spill drinks on keyboards, unplug the wrong cables, etc.  In addition, many of us, in our lives as DBAs or developers, must have observed, caused, or corrected one or more of the following unpleasant events: Accidentally updated a table with wrong values !! Performed a batch update that went wrong - due to logical errors in the code !! Dropped a table !! How do DBAs typically recover from these types of errors? First, data needs to be restored and recovered to the point-in-time when the error occurred (incomplete or point-in-time recovery).  Moreover, depending on the type of fault, it’s possible that some services – or even the entire database – would have to be taken down during the recovery process.Apart from error conditions, there are other questions that need to be addressed as part of the investigation. For example, what did the data look like in the morning, prior to the error? What were the various changes to the row(s) between two timestamps? Who performed the transaction and how can it be reversed?  Oracle Database includes built-in Flashback technologies, with features that address these challenges and questions, and enable you to perform faster, easier, and convenient recovery from logical corruptions. HistoryFlashback Query, the first Flashback Technology, was introduced in Oracle 9i. It provides a simple, powerful and completely non-disruptive mechanism for data verification and recovery from logical errors, and enables users to view the state of data at a previous point in time.Flashback Technologies were further enhanced in Oracle 10g, to provide fast, easy recovery at the database, table, row, and even at a transaction level.Oracle Database 11g introduced an innovative method to manage and query long-term historical data with Flashback Data Archive. The 11g release also introduced Flashback Transaction, which provides an easy, one-step operation to back out a transaction. Oracle Database versions 11.2.0.2 and beyond further enhanced the performance of these features. Note that all the features listed here work without requiring any kind of restore operation.In addition, Flashback features are fully supported with the new multi-tenant capabilities introduced with Oracle Database 12c, Flashback Features Oracle Flashback Database enables point-in-time-recovery of the entire database without requiring a traditional restore and recovery operation. It rewinds the entire database to a specified point in time in the past by undoing all the changes that were made since that time.Oracle Flashback Table enables an entire table or a set of tables to be recovered to a point in time in the past.Oracle Flashback Drop enables accidentally dropped tables and all dependent objects to be restored.Oracle Flashback Query enables data to be viewed at a point-in-time in the past. This feature can be used to view and reconstruct data that was lost due to unintentional change(s) or deletion(s). This feature can also be used to build self-service error correction into applications, empowering end-users to undo and correct their errors.Oracle Flashback Version Query offers the ability to query the historical changes to data between two points in time or system change numbers (SCN) Oracle Flashback Transaction Query enables changes to be examined at the transaction level. This capability can be used to diagnose problems, perform analysis, audit transactions, and even revert the transaction by undoing SQLOracle Flashback Transaction is a procedure used to back-out a transaction and its dependent transactions.Flashback technologies eliminate the need for a traditional restore and recovery process to fix logical corruptions or make enquiries. Using these technologies, you can recover from the error in the same amount of time it took to generate the error. All the Flashback features can be accessed either via SQL command line (or) via Enterprise Manager.  Most of the Flashback technologies depend on the available UNDO to retrieve older data. The following table describes the various Flashback technologies: their purpose, dependencies and situations where each individual technology can be used.   Example Syntax Error investigation related:The purpose is to investigate what went wrong and what the values were at certain points in timeFlashback Queries  ( select .. as of SCN | Timestamp )   - Helps to see the value of a row/set of rows at a point in timeFlashback Version Queries  ( select .. versions between SCN | Timestamp and SCN | Timestamp)  - Helps determine how the value evolved between certain SCNs or between timestamps Flashback Transaction Queries (select .. XID=)   - Helps to understand how the transaction caused the changes.Error correction related:The purpose is to fix the error and correct the problems,Flashback Table  (flashback table .. to SCN | Timestamp)  - To rewind the table to a particular timestamp or SCN to reverse unwanted updates Flashback Drop (flashback table ..  to before drop )  - To undrop or undelete a table Flashback Database (flashback database to SCN  | Restore Point )  - This is the rewind button for Oracle databases. You can revert the entire database to a particular point in time. It is a fast way to perform a PITR (point-in-time recovery). Flashback Transaction (DBMS_FLASHBACK.TRANSACTION_BACKOUT(XID..))  - To reverse a transaction and its related transactions Advanced use cases Flashback technology is integrated into Oracle Recovery Manager (RMAN) and Oracle Data Guard. So, apart from the basic use cases mentioned above, the following use cases are addressed using Oracle Flashback. Block Media recovery by RMAN - to perform block level recovery Snapshot Standby - where the standby is temporarily converted to a read/write environment for testing, backup, or migration purposes Re-instate old primary in a Data Guard environment – this avoids the need to restore an old backup and perform a recovery to make it a new standby. Guaranteed Restore Points - to bring back the entire database to an older point-in-time in a guaranteed way. and so on..I hope this introductory overview helps you understand how Flashback features can be used to investigate and recover from logical errors.  As mentioned earlier, I will take a deeper-dive into to some of the critical Flashback features in my upcoming blogs and address common use cases.

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  • Rotating a NetBeans Visual Library Widget

    - by Geertjan
    Trying to create a widget which, when clicked, rotates slightly further on each subsequent click: Above, the bird where the mouse is visible has been clicked a few times and so has rotated a bit further on each click. The code isn't quite right yet and I'm hoping someone will take this code, try it out, and help with a nice solution! public class BirdScene extends Scene {     public BirdScene() {         addChild(new LayerWidget(this));         getActions().addAction(ActionFactory.createAcceptAction(new AcceptProvider() {             public ConnectorState isAcceptable(Widget widget, Point point, Transferable transferable) {                 Image dragImage = getImageFromTransferable(transferable);                 if (dragImage != null) {                     JComponent view = getView();                     Graphics2D g2 = (Graphics2D) view.getGraphics();                     Rectangle visRect = view.getVisibleRect();                     view.paintImmediately(visRect.x, visRect.y, visRect.width, visRect.height);                     g2.drawImage(dragImage,                             AffineTransform.getTranslateInstance(point.getLocation().getX(),                             point.getLocation().getY()),                             null);                     return ConnectorState.ACCEPT;                 } else {                     return ConnectorState.REJECT;                 }             }             public void accept(Widget widget, final Point point, Transferable transferable) {                 addChild(new BirdWidget(getScene(), getImageFromTransferable(transferable), point));             }         }));     }     private Image getImageFromTransferable(Transferable transferable) {         Object o = null;         try {             o = transferable.getTransferData(DataFlavor.imageFlavor);         } catch (IOException ex) {         } catch (UnsupportedFlavorException ex) {         }         return o instanceof Image ? (Image) o : null;     }     private class BirdWidget extends IconNodeWidget {         private int theta = 0;         public BirdWidget(Scene scene, Image imageFromTransferable, Point point) {             super(scene);             setImage(imageFromTransferable);             setPreferredLocation(point);             setCheckClipping(true);             getActions().addAction(ActionFactory.createMoveAction());             getActions().addAction(ActionFactory.createSelectAction(new SelectProvider() {                 public boolean isAimingAllowed(Widget widget, Point localLocation, boolean invertSelection) {                     return true;                 }                 public boolean isSelectionAllowed(Widget widget, Point localLocation, boolean invertSelection) {                     return true;                 }                 public void select(final Widget widget, Point localLocation, boolean invertSelection) {                     theta = (theta + 100) % 360;                     repaint();                     getScene().validate();                 }             }));         }         @Override         public void paintWidget() {             final Image image = getImageWidget().getImage();             Graphics2D g = getGraphics();             g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);             Rectangle bounds = getClientArea();             AffineTransform newXform = g.getTransform();             int xRot = image.getWidth(null) / 2;             int yRot = image.getWidth(null) / 2;             newXform.rotate(theta * Math.PI / 180, xRot, yRot);             g.setTransform(newXform);             g.drawImage(image, bounds.x, bounds.y, null);         }     } } The problem relates to refreshing the scene after the rotation. But it would help if someone would just take the code above, add it to their own application, try it out, see the problem for yourself, and develop it a bit further!

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  • Rebooting access point via SSH with pexpect... hangs. Any ideas?

    - by MiniQuark
    When I want to reboot my D-Link DWL-3200-AP access point from my bash shell, I connect to the AP using ssh and I just type reboot in the CLI interface. After about 30 seconds, the AP is rebooted: # ssh [email protected] [email protected]'s password: ******** Welcome to Wireless SSH Console!! ['help' or '?' to see commands] Wireless Driver Rev 4.0.0.167 D-Link Access Point wlan1 -> reboot Sound's great? Well unfortunately the ssh client process never exits, for some reason (maybe the AP kills the ssh server a bit too fast, I don't know). My ssh client process is completely blocked (even if I wait for several minutes, nothing happens). I always have to wait for the AP to reboot, then open another shell, find the ssh client process ID (using ps aux | grep ssh) then kill the ssh process using kill <pid>. That's quite annoying. So I decided to write a python script to reboot the AP. The script connects to the AP's CLI interface via ssh, using python-pexpect, and it tries to launch the "reboot" command. Here's what the script looks like: #!/usr/bin/python # usage: python reboot_ap.py {host} {user} {password} import pexpect import sys import time command = "ssh %(user)s@%(host)s"%{"user":sys.argv[2], "host":sys.argv[1]} session = pexpect.spawn(command, timeout=30) # start ssh process response = session.expect(r"password:") # wait for password prompt session.sendline(sys.argv[3]) # send password session.expect(" -> ") # wait for D-Link CLI prompt session.sendline("reboot") # send the reboot command time.sleep(60) # make sure the reboot has time to actually take place session.close(force=True) # kill the ssh process The script connects properly to the AP (I tried running some other commands than reboot, they work fine), it sends the reboot command, waits for one minute, then kills the ssh process. The problem is: this time, the AP never reboots! I have no idea why. Any solution, anyone?

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  • How to save image drawn on a JPanel?

    - by swift
    I have a panel with transparent background which i use to draw an image. now problem here is when i draw anything on panel and save the image as a JPEG file its saving the image with black background but i want it to be saved as same, as i draw on the panel. what should be done for this? plz guide me j Client.java public class Client extends Thread { static DatagramSocket datasocket; static DatagramSocket socket; Point point; Whiteboard board; Virtualboard virtualboard; JLayeredPane layerpane; BufferedImage image; public Client(DatagramSocket datasocket) { Client.datasocket=datasocket; } //This function is responsible to connect to the server public static void connect() { try { socket=new DatagramSocket (9000); //client connection socket port= 9000 datasocket=new DatagramSocket (9005); //client data socket port= 9002 ByteArrayOutputStream baos=new ByteArrayOutputStream(); DataOutputStream dos=new DataOutputStream(baos); //this is to tell server that this is a connection request dos.writeChar('c'); dos.close(); byte[]data=baos.toByteArray(); //Server IP address InetAddress ip=InetAddress.getByName("10.123.97.154"); //create the UDP packet DatagramPacket packet=new DatagramPacket(data, data.length,ip , 8000); socket.send(packet); Client client=new Client(datasocket); client.createFrame(); client.run(); } catch(Exception e) { e.printStackTrace(); } } //This function is to create the JFrame public void createFrame() { JFrame frame=new JFrame("Whiteboard"); frame.setVisible(true); frame.setBackground(Color.black); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(680,501); frame.addWindowListener(new WindowAdapter() { public void windowOpened(WindowEvent e) {} public void windowClosing(WindowEvent e) { close(); } }); layerpane=frame.getLayeredPane(); board= new Whiteboard(datasocket); image = new BufferedImage(590,463, BufferedImage.TYPE_INT_ARGB); board.setBounds(74,2,590,463); board.setImage(image); virtualboard=new Virtualboard(); virtualboard.setImage(image); virtualboard.setBounds(74,2,590,463); layerpane.add(virtualboard,new Integer(2));//Panel where remote user draws layerpane.add(board,new Integer(3)); layerpane.add(board.colourButtons(),new Integer(1)); layerpane.add(board.shapeButtons(),new Integer(0)); //frame.add(paper.addButtons(),BorderLayout.WEST); } /* * This function is overridden from the thread class * This function listens for incoming packets from the server * which contains the points drawn by the other client */ public void run () { while (true) { try { byte[] buffer = new byte[512]; DatagramPacket packet = new DatagramPacket(buffer, buffer.length); datasocket.receive(packet); InputStream in=new ByteArrayInputStream(packet.getData(), packet.getOffset(),packet.getLength()); DataInputStream din=new DataInputStream(in); int x=din.readInt(); int y=din.readInt(); String varname=din.readLine(); String var[]=varname.split("-",4); point=new Point(x,y); virtualboard.addPoint(point, var[0], var[1],var[2],var[3]); } catch (IOException ex) { ex.printStackTrace(); } } } //This function is to broadcast the newly drawn point to the server public void broadcast (Point p,String varname,String shape,String event, String color) { try { ByteArrayOutputStream baos=new ByteArrayOutputStream(); DataOutputStream dos=new DataOutputStream(baos); dos.writeInt(p.x); dos.writeInt(p.y); dos.writeBytes(varname); dos.writeBytes("-"); dos.writeBytes(shape); dos.writeBytes("-"); dos.writeBytes(event); dos.writeBytes("-"); dos.writeBytes(color); dos.close(); byte[]data=baos.toByteArray(); InetAddress ip=InetAddress.getByName("10.123.97.154"); DatagramPacket packet=new DatagramPacket(data, data.length,ip , 8002); datasocket.send(packet); } catch (Exception e) { e.printStackTrace(); } } //This function is to close the client's connection with the server public void close() { try { ByteArrayOutputStream baos=new ByteArrayOutputStream(); DataOutputStream dos=new DataOutputStream(baos); //This is to tell server that this is request to remove the client dos.writeChar('r'); dos.close(); byte[]data=baos.toByteArray(); //Server IP address InetAddress ip=InetAddress.getByName("10.123.97.154"); DatagramPacket packet=new DatagramPacket(data, data.length,ip , 8000); socket.send(packet); System.out.println("closed"); } catch(Exception e) { e.printStackTrace(); } } public static void main(String[] args) throws Exception { connect(); } } Whiteboard.java class Whiteboard extends JPanel implements MouseListener,MouseMotionListener,ActionListener,KeyListener { BufferedImage image; Boolean tooltip=false; int post; String shape; String selectedcolor="black"; Color color=Color.black; //Color color=Color.white; Point start; Point end; Point mp; Point tip; int keycode; String fillshape; Point fillstart=new Point(); Point fillend=new Point(); int noofside; Button r=new Button("rect"); Button rectangle=new Button("rect"); Button line=new Button("line"); Button roundrect=new Button("roundrect"); Button polygon=new Button("poly"); Button text=new Button("text"); JButton save=new JButton("Save"); Button elipse=new Button("elipse"); ImageIcon fillicon=new ImageIcon("images/fill.jpg"); JButton fill=new JButton(fillicon); ImageIcon erasericon=new ImageIcon("images/eraser.gif"); JButton erase=new JButton(erasericon); JButton[] colourbutton=new JButton[28]; String selected; Point label; String key=""; int ex,ey;//eraser DatagramSocket dataSocket; JButton button = new JButton("test"); Client client; Boolean first; int w,h; public Whiteboard(DatagramSocket dataSocket) { try { UIManager.setLookAndFeel( UIManager.getCrossPlatformLookAndFeelClassName()); } catch (Exception e) { e.printStackTrace(); } setLayout(null); setOpaque(false); setBackground(new Color(237,237,237)); this.dataSocket=dataSocket; client=new Client(dataSocket); addKeyListener(this); addMouseListener(this); addMouseMotionListener(this); setBorder(BorderFactory.createLineBorder(Color.black)); } public void paintComponent(Graphics g) { try { super.paintComponent(g); g.drawImage(image, 0, 0, this); Graphics2D g2 = (Graphics2D)g; if(color!=null) g2.setPaint(color); if(start!=null && end!=null) { if(selected==("elipse")) g2.drawOval(start.x, start.y,(end.x-start.x),(end.y-start.y)); else if(selected==("rect")) g2.drawRect(start.x, start.y, (end.x-start.x),(end.y-start.y)); else if(selected==("rrect")) g2.drawRoundRect(start.x, start.y, (end.x-start.x),(end.y-start.y),11,11); else if(selected==("line")) g2.drawLine(start.x,start.y,end.x,end.y); else if(selected==("poly")) { g2.drawLine(start.x,start.y,end.x,end.y); client.broadcast(start, "start", "poly", "drag", selectedcolor); client.broadcast(end, "end", "poly", "drag", selectedcolor); } } if(tooltip==true) { System.out.println(selected); if(selected=="text") { g2.drawString("|", tip.x, tip.y-5); g2.drawString("Click to add text", tip.x+10, tip.y+23); g2.drawString("__", label.x+post, label.y); } if(selected=="erase") { g2.setPaint(new Color(237,237,237)); g2.fillRect(tip.x-10,tip.y-10,10,10); g2.setPaint(color); g2.drawRect(tip.x-10,tip.y-10,10,10); } } } catch(Exception e) {} } //Function to draw the shape on image public void draw() { Graphics2D g2 = (Graphics2D) image.createGraphics(); Font font=new Font("Times New Roman",Font.PLAIN,14); g2.setFont(font); g2.setPaint(color); if(start!=null && end!=null) { if(selected=="line") g2.drawLine(start.x, start.y, end.x, end.y); else if(selected=="elipse") g2.drawOval(start.x, start.y, (end.x-start.x),(end.y-start.y)); else if(selected=="rect") g2.drawRect(start.x, start.y, (end.x-start.x),(end.y-start.y)); else if(selected==("rrect")) g2.drawRoundRect(start.x, start.y, (end.x-start.x),(end.y-start.y),11,11); else if(selected==("poly")) { g2.drawLine(start.x,start.y,end.x,end.y); client.broadcast(start, "start", "poly", "release", selectedcolor); client.broadcast(end, "end", "poly", "release", selectedcolor); } fillstart=start; fillend=end; fillshape=selected; } if(selected!="poly") { start=null; end=null; } if(label!=null) { if(selected==("text")) { g2.drawString(key,label.x,label.y); client.broadcast(label, key, "text", "release", selectedcolor); } } repaint(); g2.dispose(); } //Function which provides the erase functionality public void erase() { Graphics2D pic=(Graphics2D) image.createGraphics(); Color erasecolor=new Color(237,237,237); pic.setPaint(erasecolor); if(start!=null) pic.fillRect(start.x-10, start.y-10, 10, 10); } //To set the size of the image public void setImage(BufferedImage image) { this.image = image; } //Function to add buttons into the panel, calling this function returns a panel public JPanel shapeButtons() { JPanel shape=new JPanel(); shape.setBackground(new Color(181, 197, 210)); shape.setLayout(new GridLayout(5,2,2,4)); shape.setBounds(0, 2, 74, 166); rectangle.addActionListener(this); rectangle.setToolTipText("Rectangle"); line.addActionListener( this); line.setToolTipText("Line"); erase.addActionListener(this); erase.setToolTipText("Eraser"); roundrect.addActionListener(this); roundrect.setToolTipText("Round edge Rectangle"); polygon.addActionListener(this); polygon.setToolTipText("Polygon"); text.addActionListener(this); text.setToolTipText("Text"); fill.addActionListener(this); fill.setToolTipText("Fill with colour"); elipse.addActionListener(this); elipse.setToolTipText("Elipse"); save.addActionListener(this); shape.add(elipse); shape.add(rectangle); shape.add(roundrect); shape.add(polygon); shape.add(line); shape.add(text); shape.add(fill); shape.add(erase); shape.add(save); return shape; } public JPanel colourButtons() { JPanel colourbox=new JPanel(); colourbox.setBackground(new Color(181, 197, 210)); colourbox.setLayout(new GridLayout(8,2,8,8)); colourbox.setBounds(0,323,70,140); //colourbox.add(empty); for(int i=0;i<16;i++) { colourbutton[i]=new JButton(); colourbox.add(colourbutton[i]); if(i==0) colourbutton[0].setBackground(Color.black); else if(i==1) colourbutton[1].setBackground(Color.white); else if(i==2) colourbutton[2].setBackground(Color.red); else if(i==3) colourbutton[3].setBackground(Color.orange); else if(i==4) colourbutton[4].setBackground(Color.blue); else if(i==5) colourbutton[5].setBackground(Color.green); else if(i==6) colourbutton[6].setBackground(Color.pink); else if(i==7) colourbutton[7].setBackground(Color.magenta); else if(i==8) colourbutton[8].setBackground(Color.cyan); else if(i==9) colourbutton[9].setBackground(Color.black); else if(i==10) colourbutton[10].setBackground(Color.yellow); else if(i==11) colourbutton[11].setBackground(new Color(131,168,43)); else if(i==12) colourbutton[12].setBackground(new Color(132,0,210)); else if(i==13) colourbutton[13].setBackground(new Color(193,17,92)); else if(i==14) colourbutton[14].setBackground(new Color(129,82,50)); else if(i==15) colourbutton[15].setBackground(new Color(64,128,128)); colourbutton[i].addActionListener(this); } return colourbox; } public void fill() { if(selected=="fill") { Graphics2D g2 = (Graphics2D) image.getGraphics(); g2.setPaint(color); System.out.println("Fill"); if(fillshape=="elipse") g2.fillOval(fillstart.x, fillstart.y, (fillend.x-fillstart.x),(fillend.y-fillstart.y)); else if(fillshape=="rect") g2.fillRect(fillstart.x, fillstart.y, (fillend.x-fillstart.x),(fillend.y-fillstart.y)); else if(fillshape==("rrect")) g2.fillRoundRect(fillstart.x, fillstart.y, (fillend.x-fillstart.x),(fillend.y-fillstart.y),11,11); // else if(fillshape==("poly")) // g2.drawPolygon(x,y,2); } repaint(); } //To save the image drawn public void save() { try { ByteArrayOutputStream bos = new ByteArrayOutputStream(); JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(bos); JFileChooser fc = new JFileChooser(); fc.showSaveDialog(this); encoder.encode(image); byte[] jpgData = bos.toByteArray(); FileOutputStream fos = new FileOutputStream(fc.getSelectedFile()+".jpeg"); fos.write(jpgData); fos.close(); //add replce confirmation here } catch (IOException e) { System.out.println(e); } } public void mouseClicked(MouseEvent e) { } @Override public void mouseEntered(MouseEvent e) { } public void mouseExited(MouseEvent arg0) { } public void mousePressed(MouseEvent e) { if(selected=="line"||selected=="text") { start=e.getPoint(); client.broadcast(start,"start", selected,"press", selectedcolor); } else if(selected=="elipse"||selected=="rect"||selected=="rrect") mp = e.getPoint(); else if(selected=="poly") { if(first==true) { start=e.getPoint(); //client.broadcast(start,"start", selected,"press", selectedcolor); } else if(first==false) { end=e.getPoint(); repaint(); //client.broadcast(end,"end", selected,"press", selectedcolor); } } else if(selected=="erase") { start=e.getPoint(); erase(); } } public void mouseReleased(MouseEvent e) { if(selected=="text") { System.out.println("Reset"); key=""; post=0; label=new Point(); label=e.getPoint(); grabFocus(); } if(start!=null && end!=null) { if(selected=="line") { end=e.getPoint(); client.broadcast(end,"end", selected,"release", selectedcolor); draw(); } else if(selected=="elipse"||selected=="rect"||selected=="rrect") { end.x = Math.max(mp.x,e.getX()); end.y = Math.max(mp.y,e.getY()); client.broadcast(end,"end", selected,"release", selectedcolor); draw(); } else if(selected=="poly") { draw(); first=false; start=end; end=null; } } } public void mouseDragged(MouseEvent e) { if(end==null) end = new Point(); if(start==null) start = new Point(); if(selected=="line") { end=e.getPoint(); client.broadcast(end,"end", selected,"drag", selectedcolor); } else if(selected=="erase") { start=e.getPoint(); erase(); client.broadcast(start,"start", selected,"drag", selectedcolor); } else if(selected=="elipse"||selected=="rect"||selected=="rrect") { start.x = Math.min(mp.x,e.getX()); start.y = Math.min(mp.y,e.getY()); end.x = Math.max(mp.x,e.getX()); end.y = Math.max(mp.y,e.getY()); client.broadcast(start,"start", selected,"drag", selectedcolor); client.broadcast(end,"end", selected,"drag", selectedcolor); } else if(selected=="poly") end=e.getPoint(); System.out.println(tooltip); if(tooltip==true) { if(selected=="erase") { Graphics2D g2=(Graphics2D) getGraphics(); tip=e.getPoint(); g2.drawRect(tip.x-10,tip.y-10,10,10); } } repaint(); } public void mouseMoved(MouseEvent e) { if(selected=="text" ||selected=="erase") { tip=new Point(); tip=e.getPoint(); tooltip=true; repaint(); } } public void actionPerformed(ActionEvent e) { if(e.getSource()==elipse) selected="elipse"; else if(e.getSource()==line) selected="line"; else if(e.getSource()==rectangle) selected="rect"; else if(e.getSource()==erase) { selected="erase"; tooltip=true; System.out.println(selected); erase(); } else if(e.getSource()==roundrect) selected="rrect"; else if(e.getSource()==polygon) { selected="poly"; first=true; start=null; } else if(e.getSource()==text) { selected="text"; tooltip=true; } else if(e.getSource()==fill) { selected="fill"; fill(); } else if(e.getSource()==save) save(); if(e.getSource()==colourbutton[0]) { color=Color.black; selectedcolor="black"; } else if(e.getSource()==colourbutton[1]) { color=Color.white; selectedcolor="white"; } else if(e.getSource()==colourbutton[2]) { color=Color.red; selectedcolor="red"; } else if(e.getSource()==colourbutton[3]) { color=Color.orange; selectedcolor="orange"; } else if(e.getSource()==colourbutton[4]) { selectedcolor="blue"; color=Color.blue; } else if(e.getSource()==colourbutton[5]) { selectedcolor="green"; color=Color.green; } else if(e.getSource()==colourbutton[6]) { selectedcolor="pink"; color=Color.pink; } else if(e.getSource()==colourbutton[7]) { selectedcolor="magenta"; color=Color.magenta; } else if(e.getSource()==colourbutton[8]) { selectedcolor="cyan"; color=Color.cyan; } } @Override public void keyPressed(KeyEvent e) { //System.out.println(e.getKeyChar()+" : "+e.getKeyCode()); if(label!=null) { if(e.getKeyCode()==10) //Check for Enter key { label.y=label.y+14; key=""; post=0; repaint(); } else if(e.getKeyCode()==8) //Backspace { try{ Graphics2D g2 = (Graphics2D) image.getGraphics(); g2.setPaint(new Color(237,237,237)); g2.fillRect(label.x+post-7, label.y-13, 14, 17); if(post>0) post=post-6; keycode=0; key=key.substring(0, key.length()-1); System.out.println(key.substring(0, key.length())); repaint(); Point broadcastlabel=new Point(); broadcastlabel.x=label.x+post-7; broadcastlabel.y=label.y-13; client.broadcast(broadcastlabel, key, "text", "backspace", selectedcolor); } catch(Exception ex) {} } //Block invalid keys else if(!(e.getKeyCode()>=16 && e.getKeyCode()<=20 || e.getKeyCode()>=112 && e.getKeyCode()<=123 || e.getKeyCode()>=33 && e.getKeyCode()<=40 || e.getKeyCode()>=144 && e.getKeyCode()<=145 || e.getKeyCode()>=524 && e.getKeyCode()<=525 ||e.getKeyCode()==27||e.getKeyCode()==155 ||e.getKeyCode()==127)) { key=key+e.getKeyChar(); post=post+6; draw(); } } } @Override public void keyReleased(KeyEvent e) { } @Override public void keyTyped(KeyEvent e) { } } class Button extends JButton { String name; int i; public Button(String name) { this.name=name; try { UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); } catch (Exception e) { e.printStackTrace(); } } public Button(int i) { this.i=i; } public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2 = (Graphics2D)g; g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); //g2.setStroke(new BasicStroke(1.2f)); if (name == "line") g.drawLine(5,5,30,30); if (name == "elipse") g.drawOval(5,7,25,20); if (name== "rect") g.drawRect(5,5,25,23); if (name== "roundrect") g.drawRoundRect(5,5,25,23,10,10); int a[]=new int[]{20,9,20,23,20}; int b[]=new int[]{9,23,25,20,9}; if (name== "poly") g.drawPolyline(a, b, 5); if (name== "text") g.drawString("Text",8, 24); } }

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  • Can I use the [] operator in C++ to create virtual arrays

    - by Shane MacLaughlin
    I have a large code base, originally C ported to C++ many years ago, that is operating on a number of large arrays of spatial data. These arrays contain structs representing point and triangle entities that represent surface models. I need to refactor the code such that the specific way these entities are stored internally varies for specific scenarios. For example if the points lie on a regular flat grid, I don't need to store the X and Y coordinates, as they can be calculated on the fly, as can the triangles. Similarly, I want to take advantage of out of core tools such as STXXL for storage. The simplest way of doing this is replacing array access with put and get type functions, e.g. point[i].x = XV; becomes Point p = GetPoint(i); p.x = XV; PutPoint(i,p); As you can imagine, this is a very tedious refactor on a large code base, prone to all sorts of errors en route. What I'd like to do is write a class that mimics the array by overloading the [] operator. As the arrays already live on the heap, and move around with reallocs, the code already assumes that references into the array such as point *p = point + i; may not be used. Is this class feasible to write? For example writing the methods below in terms of the [] operator; void MyClass::PutPoint(int Index, Point p) { if (m_StorageStrategy == RegularGrid) { int xoffs,yoffs; ComputeGridFromIndex(Index,xoffs,yoffs); StoreGridPoint(xoffs,yoffs,p.z); } else m_PointArray[Index] = p; } } Point MyClass::GetPoint(int Index) { if (m_StorageStrategy == RegularGrid) { int xoffs,yoffs; ComputeGridFromIndex(Index,xoffs,yoffs); return GetGridPoint(xoffs,yoffs); // GetGridPoint returns Point } else return m_PointArray[Index]; } } My concern is that all the array classes I've seen tend to pass by reference, whereas I think I'll have to pass structs by value. I think it should work put other than performance, can anyone see any major pitfalls with this approach. n.b. the reason I have to pass by value is to get point[a].z = point[b].z + point[c].z to work correctly where the underlying storage type varies.

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  • 3D Graphics with XNA Game Studio 4.0 bug in light map?

    - by Eibis
    i'm following the tutorials on 3D Graphics with XNA Game Studio 4.0 and I came up with an horrible effect when I tried to implement the Light Map http://i.stack.imgur.com/BUWvU.jpg this effect shows up when I look towards the center of the house (and it moves with me). it has this shape because I'm using a sphere to represent light; using other light shapes gives different results. I'm using a class PreLightingRenderer: using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; using Dhpoware; using Microsoft.Xna.Framework.Content; namespace XNAFirstPersonCamera { public class PrelightingRenderer { // Normal, depth, and light map render targets RenderTarget2D depthTarg; RenderTarget2D normalTarg; RenderTarget2D lightTarg; // Depth/normal effect and light mapping effect Effect depthNormalEffect; Effect lightingEffect; // Point light (sphere) mesh Model lightMesh; // List of models, lights, and the camera public List<CModel> Models { get; set; } public List<PPPointLight> Lights { get; set; } public FirstPersonCamera Camera { get; set; } GraphicsDevice graphicsDevice; int viewWidth = 0, viewHeight = 0; public PrelightingRenderer(GraphicsDevice GraphicsDevice, ContentManager Content) { viewWidth = GraphicsDevice.Viewport.Width; viewHeight = GraphicsDevice.Viewport.Height; // Create the three render targets depthTarg = new RenderTarget2D(GraphicsDevice, viewWidth, viewHeight, false, SurfaceFormat.Single, DepthFormat.Depth24); normalTarg = new RenderTarget2D(GraphicsDevice, viewWidth, viewHeight, false, SurfaceFormat.Color, DepthFormat.Depth24); lightTarg = new RenderTarget2D(GraphicsDevice, viewWidth, viewHeight, false, SurfaceFormat.Color, DepthFormat.Depth24); // Load effects depthNormalEffect = Content.Load<Effect>(@"Effects\PPDepthNormal"); lightingEffect = Content.Load<Effect>(@"Effects\PPLight"); // Set effect parameters to light mapping effect lightingEffect.Parameters["viewportWidth"].SetValue(viewWidth); lightingEffect.Parameters["viewportHeight"].SetValue(viewHeight); // Load point light mesh and set light mapping effect to it lightMesh = Content.Load<Model>(@"Models\PPLightMesh"); lightMesh.Meshes[0].MeshParts[0].Effect = lightingEffect; this.graphicsDevice = GraphicsDevice; } public void Draw() { drawDepthNormalMap(); drawLightMap(); prepareMainPass(); } void drawDepthNormalMap() { // Set the render targets to 'slots' 1 and 2 graphicsDevice.SetRenderTargets(normalTarg, depthTarg); // Clear the render target to 1 (infinite depth) graphicsDevice.Clear(Color.White); // Draw each model with the PPDepthNormal effect foreach (CModel model in Models) { model.CacheEffects(); model.SetModelEffect(depthNormalEffect, false); model.Draw(Camera.ViewMatrix, Camera.ProjectionMatrix, Camera.Position); model.RestoreEffects(); } // Un-set the render targets graphicsDevice.SetRenderTargets(null); } void drawLightMap() { // Set the depth and normal map info to the effect lightingEffect.Parameters["DepthTexture"].SetValue(depthTarg); lightingEffect.Parameters["NormalTexture"].SetValue(normalTarg); // Calculate the view * projection matrix Matrix viewProjection = Camera.ViewMatrix * Camera.ProjectionMatrix; // Set the inverse of the view * projection matrix to the effect Matrix invViewProjection = Matrix.Invert(viewProjection); lightingEffect.Parameters["InvViewProjection"].SetValue(invViewProjection); // Set the render target to the graphics device graphicsDevice.SetRenderTarget(lightTarg); // Clear the render target to black (no light) graphicsDevice.Clear(Color.Black); // Set render states to additive (lights will add their influences) graphicsDevice.BlendState = BlendState.Additive; graphicsDevice.DepthStencilState = DepthStencilState.None; foreach (PPPointLight light in Lights) { // Set the light's parameters to the effect light.SetEffectParameters(lightingEffect); // Calculate the world * view * projection matrix and set it to // the effect Matrix wvp = (Matrix.CreateScale(light.Attenuation) * Matrix.CreateTranslation(light.Position)) * viewProjection; lightingEffect.Parameters["WorldViewProjection"].SetValue(wvp); // Determine the distance between the light and camera float dist = Vector3.Distance(Camera.Position, light.Position); // If the camera is inside the light-sphere, invert the cull mode // to draw the inside of the sphere instead of the outside if (dist < light.Attenuation) graphicsDevice.RasterizerState = RasterizerState.CullClockwise; // Draw the point-light-sphere lightMesh.Meshes[0].Draw(); // Revert the cull mode graphicsDevice.RasterizerState = RasterizerState.CullCounterClockwise; } // Revert the blending and depth render states graphicsDevice.BlendState = BlendState.Opaque; graphicsDevice.DepthStencilState = DepthStencilState.Default; // Un-set the render target graphicsDevice.SetRenderTarget(null); } void prepareMainPass() { foreach (CModel model in Models) foreach (ModelMesh mesh in model.Model.Meshes) foreach (ModelMeshPart part in mesh.MeshParts) { // Set the light map and viewport parameters to each model's effect if (part.Effect.Parameters["LightTexture"] != null) part.Effect.Parameters["LightTexture"].SetValue(lightTarg); if (part.Effect.Parameters["viewportWidth"] != null) part.Effect.Parameters["viewportWidth"].SetValue(viewWidth); if (part.Effect.Parameters["viewportHeight"] != null) part.Effect.Parameters["viewportHeight"].SetValue(viewHeight); } } } } that uses three effect: PPDepthNormal.fx float4x4 World; float4x4 View; float4x4 Projection; struct VertexShaderInput { float4 Position : POSITION0; float3 Normal : NORMAL0; }; struct VertexShaderOutput { float4 Position : POSITION0; float2 Depth : TEXCOORD0; float3 Normal : TEXCOORD1; }; VertexShaderOutput VertexShaderFunction(VertexShaderInput input) { VertexShaderOutput output; float4x4 viewProjection = mul(View, Projection); float4x4 worldViewProjection = mul(World, viewProjection); output.Position = mul(input.Position, worldViewProjection); output.Normal = mul(input.Normal, World); // Position's z and w components correspond to the distance // from camera and distance of the far plane respectively output.Depth.xy = output.Position.zw; return output; } // We render to two targets simultaneously, so we can't // simply return a float4 from the pixel shader struct PixelShaderOutput { float4 Normal : COLOR0; float4 Depth : COLOR1; }; PixelShaderOutput PixelShaderFunction(VertexShaderOutput input) { PixelShaderOutput output; // Depth is stored as distance from camera / far plane distance // to get value between 0 and 1 output.Depth = input.Depth.x / input.Depth.y; // Normal map simply stores X, Y and Z components of normal // shifted from (-1 to 1) range to (0 to 1) range output.Normal.xyz = (normalize(input.Normal).xyz / 2) + .5; // Other components must be initialized to compile output.Depth.a = 1; output.Normal.a = 1; return output; } technique Technique1 { pass Pass1 { VertexShader = compile vs_1_1 VertexShaderFunction(); PixelShader = compile ps_2_0 PixelShaderFunction(); } } PPLight.fx float4x4 WorldViewProjection; float4x4 InvViewProjection; texture2D DepthTexture; texture2D NormalTexture; sampler2D depthSampler = sampler_state { texture = ; minfilter = point; magfilter = point; mipfilter = point; }; sampler2D normalSampler = sampler_state { texture = ; minfilter = point; magfilter = point; mipfilter = point; }; float3 LightColor; float3 LightPosition; float LightAttenuation; // Include shared functions #include "PPShared.vsi" struct VertexShaderInput { float4 Position : POSITION0; }; struct VertexShaderOutput { float4 Position : POSITION0; float4 LightPosition : TEXCOORD0; }; VertexShaderOutput VertexShaderFunction(VertexShaderInput input) { VertexShaderOutput output; output.Position = mul(input.Position, WorldViewProjection); output.LightPosition = output.Position; return output; } float4 PixelShaderFunction(VertexShaderOutput input) : COLOR0 { // Find the pixel coordinates of the input position in the depth // and normal textures float2 texCoord = postProjToScreen(input.LightPosition) + halfPixel(); // Extract the depth for this pixel from the depth map float4 depth = tex2D(depthSampler, texCoord); // Recreate the position with the UV coordinates and depth value float4 position; position.x = texCoord.x * 2 - 1; position.y = (1 - texCoord.y) * 2 - 1; position.z = depth.r; position.w = 1.0f; // Transform position from screen space to world space position = mul(position, InvViewProjection); position.xyz /= position.w; // Extract the normal from the normal map and move from // 0 to 1 range to -1 to 1 range float4 normal = (tex2D(normalSampler, texCoord) - .5) * 2; // Perform the lighting calculations for a point light float3 lightDirection = normalize(LightPosition - position); float lighting = clamp(dot(normal, lightDirection), 0, 1); // Attenuate the light to simulate a point light float d = distance(LightPosition, position); float att = 1 - pow(d / LightAttenuation, 6); return float4(LightColor * lighting * att, 1); } technique Technique1 { pass Pass1 { VertexShader = compile vs_1_1 VertexShaderFunction(); PixelShader = compile ps_2_0 PixelShaderFunction(); } } PPShared.vsi has some common functions: float viewportWidth; float viewportHeight; // Calculate the 2D screen position of a 3D position float2 postProjToScreen(float4 position) { float2 screenPos = position.xy / position.w; return 0.5f * (float2(screenPos.x, -screenPos.y) + 1); } // Calculate the size of one half of a pixel, to convert // between texels and pixels float2 halfPixel() { return 0.5f / float2(viewportWidth, viewportHeight); } and finally from the Game class I set up in LoadContent with: effect = Content.Load(@"Effects\PPModel"); models[0] = new CModel(Content.Load(@"Models\teapot"), new Vector3(-50, 80, 0), new Vector3(0, 0, 0), 1f, Content.Load(@"Textures\prova_texture_autocad"), GraphicsDevice); house = new CModel(Content.Load(@"Models\house"), new Vector3(0, 0, 0), new Vector3((float)-Math.PI / 2, 0, 0), 35.0f, Content.Load(@"Textures\prova_texture_autocad"), GraphicsDevice); models[0].SetModelEffect(effect, true); house.SetModelEffect(effect, true); renderer = new PrelightingRenderer(GraphicsDevice, Content); renderer.Models = new List(); renderer.Models.Add(house); renderer.Models.Add(models[0]); renderer.Lights = new List() { new PPPointLight(new Vector3(0, 120, 0), Color.White * .85f, 2000) }; where PPModel.fx is: float4x4 World; float4x4 View; float4x4 Projection; texture2D BasicTexture; sampler2D basicTextureSampler = sampler_state { texture = ; addressU = wrap; addressV = wrap; minfilter = anisotropic; magfilter = anisotropic; mipfilter = linear; }; bool TextureEnabled = true; texture2D LightTexture; sampler2D lightSampler = sampler_state { texture = ; minfilter = point; magfilter = point; mipfilter = point; }; float3 AmbientColor = float3(0.15, 0.15, 0.15); float3 DiffuseColor; #include "PPShared.vsi" struct VertexShaderInput { float4 Position : POSITION0; float2 UV : TEXCOORD0; }; struct VertexShaderOutput { float4 Position : POSITION0; float2 UV : TEXCOORD0; float4 PositionCopy : TEXCOORD1; }; VertexShaderOutput VertexShaderFunction(VertexShaderInput input) { VertexShaderOutput output; float4x4 worldViewProjection = mul(World, mul(View, Projection)); output.Position = mul(input.Position, worldViewProjection); output.PositionCopy = output.Position; output.UV = input.UV; return output; } float4 PixelShaderFunction(VertexShaderOutput input) : COLOR0 { // Sample model's texture float3 basicTexture = tex2D(basicTextureSampler, input.UV); if (!TextureEnabled) basicTexture = float4(1, 1, 1, 1); // Extract lighting value from light map float2 texCoord = postProjToScreen(input.PositionCopy) + halfPixel(); float3 light = tex2D(lightSampler, texCoord); light += AmbientColor; return float4(basicTexture * DiffuseColor * light, 1); } technique Technique1 { pass Pass1 { VertexShader = compile vs_1_1 VertexShaderFunction(); PixelShader = compile ps_2_0 PixelShaderFunction(); } } I don't have any idea on what's wrong... googling the web I found that this tutorial may have some bug but I don't know if it's the LightModel fault (the sphere) or in a shader or in the class PrelightingRenderer. Any help is very appreciated, thank you for reading!

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