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  • Unable to mount USBDRIVE Error creating moint point: Permission denied

    - by steve
    Whenever I plug a usb into my computer a window pops up and says Unable to mount [Name of USB] Error creating moint point: Permission denied steve@goliath:/$ uname -a Linux goliath 3.2.0-32-generic #51-Ubuntu SMP Wed Sep 26 21:33:09 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux steve@goliath:/$ sudo fdisk -l WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sda: 120.0 GB, 120034123776 bytes 255 heads, 63 sectors/track, 14593 cylinders, total 234441648 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0f716ee1 Device Boot Start End Blocks Id System /dev/sda1 1 234441647 117220823+ ee GPT WARNING: GPT (GUID Partition Table) detected on '/dev/sdb'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sdb: 1500.3 GB, 1500301910016 bytes 255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0f710ee1 Device Boot Start End Blocks Id System /dev/sdb1 1 2930277167 1465138583+ ee GPT Disk /dev/sdc: 16.0 GB, 16005464064 bytes 74 heads, 10 sectors/track, 42244 cylinders, total 31260672 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xc3072e18 Device Boot Start End Blocks Id System /dev/sdc1 8064 31260671 15626304 c W95 FAT32 (LBA) steve@goliath:/$ sudo mkdir /media/external mkdir: cannot create directory `/media/external': Permission denied steve@goliath:/$ sudo mkdir /media/usb0 mkdir: cannot create directory `/media/usb0': Permission denied steve@goliath:/$ sudo ls -l / | grep media drwxr-xr-x 3 root root 4096 Oct 3 22:48 media steve@goliath:/$ ls /media/ -a . .. MediaShare MediaShare is the the directory on my server that has all my movies and music. If there is any information I left out please let me know.

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  • Floating point undesirable in highly critical code?

    - by Kirt Undercoffer
    Question 11 in the Software Quality section of "IEEE Computer Society Real-World Software Engineering Problems", Naveda, Seidman, lists fp computation as undesirable because "the accuracy of the computations cannot be guaranteed". This is in the context of computing acceleration for an emergency braking system for a high speed train. This thinking seems to be invoking possible errors in small differences between measurements of a moving object but small differences at slow speeds aren't a problem (or shouldn't be), small differences between two measurements at high speed are irrelevant - can there be a problem with small roundoff errors during deceleration for an emergency braking system? This problem has been observed with airplane braking systems resulting in hydroplaning but could this actually happen in the context of a high speed train? The concern about fp errors seems to not be well-founded in this context. Any insight? The fp is used for acceleration so perhaps the concern is inching over a speed limit? But fp should be just fine if they use a double in whatever implementation language. The actual problem in the text states: During the inspection of the code for the emergency braking system of a new high speed train (a highly critical, real-time application), the review team identifies several characteristics of the code. Which of these characteristics are generally viewed as undesirable? The code contains three recursive functions (well that one is obvious). The computation of acceleration uses floating point arithmetic. All other computations use integer arithmetic. The code contains one linked list that uses dynamic memory allocation (second obvious problem). All inputs are checked to determine that they are within expected bounds before they are used.

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  • Extended service set help [closed]

    - by Cygnus X
    Sorry, this is going to be long and rambly. So, at home my network is set up as such: I have a "master router" that handles DHCP, from there I have a basic 5 port switch, and coming off that, I have a second router that I put in access point mode so that I could have better wireless coverage in my house. I cant seem to access it through a web browser since the master router kicked in and assigned it an ip address. But, i told you all that story, so that i could tell you this story. At the company I work for, they are trying to set up wireless cameras, according to the manual for these, in order to connect these cameras to our network, we need to get into the wireless router and associate the router with the cameras, but the problem is, the network is setup like my home network. Theres a "master router" which is a windows 2003 server, and then a wireless router in AP mode dishing out wireless access. I cant get into the router (by the way I'm not the system admin for the company, nor do i know jack squat about windows server , nor can I easily get in contact with the system admin. (quite the cluster f*k, eh?)) I've tried using wireshark to find the routers ip, dug through arp tables, tried plugging straight into the router, but I cant seem to get into the damn thing. Any ideas/suggestions would be greatly appreciated.

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  • Does "epsilon" really guarantees anything in floating-point computations?!

    - by Michal Czardybon
    To make the problem short let's say I want to compute expression: a / (b - c) on float's. To make sure the result is meaningful, I can check if 'b' and 'c' are inequal: float eps = std::numeric_limits<float>::epsilon(); if ((b - c) > EPS || (c - b) > EPS) { return a / (b - c); } but my tests show it is not enough to guarantee either meaningful results nor not failing to provide a result if it is possible. Case 1: a = 1.0f; b = 0.00000003f; c = 0.00000002f; Result: The if condition is NOT met, but the expression would produce a correct result 100000008 (as for the floats' precision). Case 2: a = 1e33f; b = 0.000003; c = 0.000002; Result: The if condition is met, but the expression produces not a meaningful result +1.#INF00. I found it much more reliable to check the result, not the arguments: const float INF = numeric_limits<float>::infinity(); float x = a / (b - c); if (-INF < x && x < INF) { return x; } But what for is the epsilon then and why is everyone saying epsilon is good to use?

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  • How can I compare the performance of log() and fp division in C++?

    - by Ventzi Zhechev
    Hi, I’m using a log-based class in C++ to store very small floating-point values (as the values otherwise go beyond the scope of double). As I’m performing a large number of multiplications, this has the added benefit of converting the multiplications to sums. However, at a certain point in my algorithm, I need to divide a standard double value by an integer value and than do a *= to a log-based value. I have overloaded the *= operator for my log-based class and the right-hand side value is first converted to a log-based value by running log() and than added to the left-hand side value. Thus the operations actually performed are floating-point division, log() and floating-point summation. My question whether it would be faster to first convert the denominator to a log-based value, which would replace the floating-point division with floating-point subtraction, yielding the following chain of operations: twice log(), floating-point subtraction, floating-point summation. In the end, this boils down to whether floating-point division is faster or slower than log(). I suspect that a common answer would be that this is compiler and architecture dependent, so I’ll say that I use gcc 4.2 from Apple on darwin 10.3.0. Still, I hope to get an answer with a general remark on the speed of these two operators and/or an idea on how to measure the difference myself, as there might be more going on here, e.g. executing the constructors that do the type conversion etc. Cheers!

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  • I am trying to access the individual bytes in a floating point number and I am getting unexpected results

    - by oweinh
    So I have this so far: #include <iostream> #include <string> #include <typeinfo> using namespace std; int main () { float f = 3.45; // just an example fp# char* ptr = (char*)&f; // a character pointer to the first byte of the fp#? cout << int(ptr[0]) << endl; // these lines are just to see if I get what I cout << int(ptr[1]) << endl; // am looking for... I want ints that I can cout << int(ptr[2]) << endl; // otherwise manipulate. cout << int(ptr[3]) << endl; } the result is: -51 -52 92 64 so obviously -51 and -52 are not in the byte range that I would expect for a char... I have taken information from similar questions to arrive at this code and from all discussions, a conversion from char to int is straightforward. So why negative values? I am trying to look at a four-byte number, therefore I would expect 4 integers, each in the range 0-255. I am using Codeblocks 13.12 with gcc 4.8.1 with option -std=C++11 on a Windows 8.1 device.

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  • Hostapd - WLAN as AP

    - by BBK
    I'm trying to start hostapd but without success. I'm using Headless Ubuntu 11.10 oneiric 3.0.0-16-server x86_64. WLAN driver is rt2800usb and my wireless nic card TP-Link TL-WN727N supports AP mode as shows below: us0# ifconfig wlan0 wlan0 Link encap:Ethernet HWaddr 00:27:19:be:cd:b6 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) us0# lsusb Bus 003 Device 003: ID 148f:3070 Ralink Technology, Corp. RT2870/RT3070 Wireless Adapter us0# lshw -C network *-network:3 description: Wireless interface physical id: 4 bus info: usb@3:2 logical name: wlan0 serial: 00:27:19:be:cd:b6 capabilities: ethernet physical wireless configuration: broadcast=yes driver=rt2800usb driverversion=3.0.0-16-server firmware=0.29 link=no multicast=yes wireless=IEEE 802.11bgn us0# hostapd /etc/hostapd/hostapd.conf Configuration file: /etc/hostapd/hostapd.conf Could not read interface wlan0 # The int flags: No such device nl80211 driver initialization failed. ELOOP: remaining socket: sock=4 eloop_data=0xd3e4a0 user_data=0xd3ecc0 handler=0x433880 ELOOP: remaining socket: sock=6 eloop_data=0xd411f0 user_data=(nil) handler=0x43cc10 us0# cat /etc/hostapd/hostapd.conf ssid=Home interface=wlan0 # The interface name of the card #driver=rt2800usb driver=nl80211 macaddr_acl=0 ieee80211n=1 channel=1 hw_mode=g auth_algs=1 ignore_broadcast_ssid=0 wpa=2 wpa_passphrase=88888888 wpa_key_mgmt=WPA-PSK wpa_pairwise=TKIP rsn_pairwise=CCMP us0# iw list Wiphy phy0 Band 1: Capabilities: 0x172 HT20/HT40 Static SM Power Save RX Greenfield RX HT20 SGI RX HT40 SGI RX STBC 1-stream Max AMSDU length: 7935 bytes No DSSS/CCK HT40 Maximum RX AMPDU length 65535 bytes (exponent: 0x003) Minimum RX AMPDU time spacing: 2 usec (0x04) HT RX MCS rate indexes supported: 0-7, 32 TX unequal modulation not supported HT TX Max spatial streams: 1 HT TX MCS rate indexes supported may differ Frequencies: * 2412 MHz [1] (20.0 dBm) * 2417 MHz [2] (20.0 dBm) * 2422 MHz [3] (20.0 dBm) * 2427 MHz [4] (20.0 dBm) * 2432 MHz [5] (20.0 dBm) * 2437 MHz [6] (20.0 dBm) * 2442 MHz [7] (20.0 dBm) * 2447 MHz [8] (20.0 dBm) * 2452 MHz [9] (20.0 dBm) * 2457 MHz [10] (20.0 dBm) * 2462 MHz [11] (20.0 dBm) * 2467 MHz [12] (20.0 dBm) (passive scanning, no IBSS) * 2472 MHz [13] (20.0 dBm) (passive scanning, no IBSS) * 2484 MHz [14] (20.0 dBm) (passive scanning, no IBSS) Bitrates (non-HT): * 1.0 Mbps * 2.0 Mbps (short preamble supported) * 5.5 Mbps (short preamble supported) * 11.0 Mbps (short preamble supported) * 6.0 Mbps * 9.0 Mbps * 12.0 Mbps * 18.0 Mbps * 24.0 Mbps * 36.0 Mbps * 48.0 Mbps * 54.0 Mbps max # scan SSIDs: 4 Supported interface modes: * IBSS * managed * AP * AP/VLAN * WDS * monitor * mesh point Supported commands: * new_interface * set_interface * new_key * new_beacon * new_station * new_mpath * set_mesh_params * set_bss * authenticate * associate * deauthenticate * disassociate * join_ibss * Unknown command (68) * Unknown command (55) * Unknown command (57) * Unknown command (59) * Unknown command (67) * set_wiphy_netns * Unknown command (65) * Unknown command (66) * connect * disconnect The question is: Why the hostapd not starting?

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  • A starting point for Use Cases and User Stories

    - by Mike Benkovich
    Originally posted on: http://geekswithblogs.net/benko/archive/2013/07/23/a-starting-point-for-use-cases-and-user-stories.aspxSoftware is a challenging business and is rife with opportunities to go wrong. Over the years a number of methodologies have evolved to help make sure that things go right. In an effort to contribute to this I’ve created a list of user stories that I think should be included and sometimes are just assumed. Note this is a work in progress, so I’m looking for your feedback. I’m curious what you would add or change in my list. · As a DBA I am working with a Normalized data model that reflects an agreed upon logical model for the system · As a DBA I am using consistent names for my fields which match the naming standards of my organization · As a DBA my model supports simple CRUD operations against all the entities · As an Application Architect the UI has been validated against the Business requirements and a complete set of user story’s have been created · As an Application Architect the database model has been validated against the UI · As an Application Architect we have a logical business model that describes all the known and/or expected usage of the system during the software’s expected lifecycle · As an Application Architect we have a Deployment diagram that describes how the application components will be deployed · As an Application Architect we have a navigation diagram that describes the typical application flow · As an Application Architect we have identified points of interaction which describes how the UI interacts with the services and the data storage · As an Application Architect we have identified external systems which may now or in the future use the data of this application and have adapted the logical model to include these interactions · As an Application Architect we have identified existing systems and tools that can be extended and/or reused to help this application achieve it’s business goals · As a Project Manager all team members understand the goals of each release and iteration as they are planned · As a Project Manager all team members understand their role and the roles of others · As a Project Manager we have support of the business to do the right thing even if it is not the expedient thing · As a Test/QA Analyst we have created a simulation environment for testing the system which does not use sensitive data and accurately reflects the scenarios of all the data that will be supported by the system · As a Test/QA Analyst we have identified the matrix of supported clients used to access the system including the likely browsers, mobile devices and other interfaces to work with the application · As a Test/QA Analyst we have created exit criteria for each user story that match the requirements of the business story that was used to create them · As a Test/QA Analyst we have access to a Test environment that is isolated from production and staging environments · As a Test/QA Analyst there we have a way to reset the environment so we can rerun tests when a new version of the software becomes available · As a Test/QA Analyst I am able to automate portions of the test process Thoughts? -mike

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  • How do I translate a point from one rect to a point in a scaled rect?

    - by Bill
    I have an image (i) that's been scaled from its original size (rectLarge) to fit a smaller rectangle (rectSmall). Given a point p in rectSmall, how can I translate this to a point in rectLarge. To make this concrete, suppose I have a 20x20 image that's been scaled to a 10x10 rect. The point (1, 1) in the smaller rect should be scaled up to a point in the larger rect (i.e. (2,2)). I'm trying to achieve this with: result.x = point.x * (destRect.size.width / srcRect.size.width ); result.y = point.y * (destRect.size.height / srcRect.size.height); However, the points generated by this code are not correct - they do not map to the appropriate point in the original image. What am I doing wrong?

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  • Python point lookup (coordinate binning?)

    - by Rince
    Greetings, I am trying to bin an array of points (x, y) into an array of boxes [(x0, y0), (x1, y0), (x0, y1), (x1, y1)] (tuples are the corner points) So far I have the following routine: def isInside(self, point, x0, x1, y0, y1): pr1 = getProduct(point, (x0, y0), (x1, y0)) if pr1 >= 0: pr2 = getProduct(point, (x1, y0), (x1, y1)) if pr2 >= 0: pr3 = getProduct(point, (x1, y1), (x0, y1)) if pr3 >= 0: pr4 = getProduct(point, (x0, y1), (x0, y0)) if pr4 >= 0: return True return False def getProduct(origin, pointA, pointB): product = (pointA[0] - origin[0])*(pointB[1] - origin[1]) - (pointB[0] - origin[0])*(pointA[1] - origin[1]) return product Is there any better way then point-by-point lookup? Maybe some not-obvious numpy routine? Thank you!

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  • Best way to handle input from a keyboard "wedge"

    - by Mykroft
    I'm writing a C# POS (point of sale) system that takes input from a keyboard wedge magcard reader. This means that any data it reads off of a mag stripe is entered as if it were typed on the keyboard very quickly. Currently I'm handling this by attaching to the KeyPress event and looking for a series of very fast key presses that contain the card swipe sentinel characters. Is there a better way to deal with this sort of input? Edit: The device does simply present the data as keystrokes and doesn't interface through some other driver. Also We use a wide range of these types of devices so ideally a method should work independent of the specific model of wedge being used. However if there is no other option I'll have to make do.

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  • Point inside Oriented Bounding Box?

    - by Milo
    I have an OBB2D class based on SAT. This is my point in OBB method: public boolean pointInside(float x, float y) { float newy = (float) (Math.sin(angle) * (y - center.y) + Math.cos(angle) * (x - center.x)); float newx = (float) (Math.cos(angle) * (x - center.x) - Math.sin(angle) * (y - center.y)); return (newy > center.y - (getHeight() / 2)) && (newy < center.y + (getHeight() / 2)) && (newx > center.x - (getWidth() / 2)) && (newx < center.x + (getWidth() / 2)); } public boolean pointInside(Vector2D v) { return pointInside(v.x,v.y); } Here is the rest of the class; the parts that pertain: public class OBB2D { private Vector2D projVec = new Vector2D(); private static Vector2D projAVec = new Vector2D(); private static Vector2D projBVec = new Vector2D(); private static Vector2D tempNormal = new Vector2D(); private Vector2D deltaVec = new Vector2D(); private ArrayList<Vector2D> collisionPoints = new ArrayList<Vector2D>(); // Corners of the box, where 0 is the lower left. private Vector2D corner[] = new Vector2D[4]; private Vector2D center = new Vector2D(); private Vector2D extents = new Vector2D(); private RectF boundingRect = new RectF(); private float angle; //Two edges of the box extended away from corner[0]. private Vector2D axis[] = new Vector2D[2]; private double origin[] = new double[2]; public OBB2D(float centerx, float centery, float w, float h, float angle) { for(int i = 0; i < corner.length; ++i) { corner[i] = new Vector2D(); } for(int i = 0; i < axis.length; ++i) { axis[i] = new Vector2D(); } set(centerx,centery,w,h,angle); } public OBB2D(float left, float top, float width, float height) { for(int i = 0; i < corner.length; ++i) { corner[i] = new Vector2D(); } for(int i = 0; i < axis.length; ++i) { axis[i] = new Vector2D(); } set(left + (width / 2), top + (height / 2),width,height,0.0f); } public void set(float centerx,float centery,float w, float h,float angle) { float vxx = (float)Math.cos(angle); float vxy = (float)Math.sin(angle); float vyx = (float)-Math.sin(angle); float vyy = (float)Math.cos(angle); vxx *= w / 2; vxy *= (w / 2); vyx *= (h / 2); vyy *= (h / 2); corner[0].x = centerx - vxx - vyx; corner[0].y = centery - vxy - vyy; corner[1].x = centerx + vxx - vyx; corner[1].y = centery + vxy - vyy; corner[2].x = centerx + vxx + vyx; corner[2].y = centery + vxy + vyy; corner[3].x = centerx - vxx + vyx; corner[3].y = centery - vxy + vyy; this.center.x = centerx; this.center.y = centery; this.angle = angle; computeAxes(); extents.x = w / 2; extents.y = h / 2; computeBoundingRect(); } //Updates the axes after the corners move. Assumes the //corners actually form a rectangle. private void computeAxes() { axis[0].x = corner[1].x - corner[0].x; axis[0].y = corner[1].y - corner[0].y; axis[1].x = corner[3].x - corner[0].x; axis[1].y = corner[3].y - corner[0].y; // Make the length of each axis 1/edge length so we know any // dot product must be less than 1 to fall within the edge. for (int a = 0; a < axis.length; ++a) { float l = axis[a].length(); float ll = l * l; axis[a].x = axis[a].x / ll; axis[a].y = axis[a].y / ll; origin[a] = corner[0].dot(axis[a]); } } public void computeBoundingRect() { boundingRect.left = JMath.min(JMath.min(corner[0].x, corner[3].x), JMath.min(corner[1].x, corner[2].x)); boundingRect.top = JMath.min(JMath.min(corner[0].y, corner[1].y),JMath.min(corner[2].y, corner[3].y)); boundingRect.right = JMath.max(JMath.max(corner[1].x, corner[2].x), JMath.max(corner[0].x, corner[3].x)); boundingRect.bottom = JMath.max(JMath.max(corner[2].y, corner[3].y),JMath.max(corner[0].y, corner[1].y)); } public void set(RectF rect) { set(rect.centerX(),rect.centerY(),rect.width(),rect.height(),0.0f); } // Returns true if other overlaps one dimension of this. private boolean overlaps1Way(OBB2D other) { for (int a = 0; a < axis.length; ++a) { double t = other.corner[0].dot(axis[a]); // Find the extent of box 2 on axis a double tMin = t; double tMax = t; for (int c = 1; c < corner.length; ++c) { t = other.corner[c].dot(axis[a]); if (t < tMin) { tMin = t; } else if (t > tMax) { tMax = t; } } // We have to subtract off the origin // See if [tMin, tMax] intersects [0, 1] if ((tMin > 1 + origin[a]) || (tMax < origin[a])) { // There was no intersection along this dimension; // the boxes cannot possibly overlap. return false; } } // There was no dimension along which there is no intersection. // Therefore the boxes overlap. return true; } public void moveTo(float centerx, float centery) { float cx,cy; cx = center.x; cy = center.y; deltaVec.x = centerx - cx; deltaVec.y = centery - cy; for (int c = 0; c < 4; ++c) { corner[c].x += deltaVec.x; corner[c].y += deltaVec.y; } boundingRect.left += deltaVec.x; boundingRect.top += deltaVec.y; boundingRect.right += deltaVec.x; boundingRect.bottom += deltaVec.y; this.center.x = centerx; this.center.y = centery; computeAxes(); } // Returns true if the intersection of the boxes is non-empty. public boolean overlaps(OBB2D other) { if(right() < other.left()) { return false; } if(bottom() < other.top()) { return false; } if(left() > other.right()) { return false; } if(top() > other.bottom()) { return false; } if(other.getAngle() == 0.0f && getAngle() == 0.0f) { return true; } return overlaps1Way(other) && other.overlaps1Way(this); } public Vector2D getCenter() { return center; } public float getWidth() { return extents.x * 2; } public float getHeight() { return extents.y * 2; } public void setAngle(float angle) { set(center.x,center.y,getWidth(),getHeight(),angle); } public float getAngle() { return angle; } public void setSize(float w,float h) { set(center.x,center.y,w,h,angle); } public float left() { return boundingRect.left; } public float right() { return boundingRect.right; } public float bottom() { return boundingRect.bottom; } public float top() { return boundingRect.top; } public RectF getBoundingRect() { return boundingRect; } public boolean overlaps(float left, float top, float right, float bottom) { if(right() < left) { return false; } if(bottom() < top) { return false; } if(left() > right) { return false; } if(top() > bottom) { return false; } return true; } public static float distance(float ax, float ay,float bx, float by) { if (ax < bx) return bx - ay; else return ax - by; } public Vector2D project(float ax, float ay) { projVec.x = Float.MAX_VALUE; projVec.y = Float.MIN_VALUE; for (int i = 0; i < corner.length; ++i) { float dot = Vector2D.dot(corner[i].x,corner[i].y,ax,ay); projVec.x = JMath.min(dot, projVec.x); projVec.y = JMath.max(dot, projVec.y); } return projVec; } public Vector2D getCorner(int c) { return corner[c]; } public int getNumCorners() { return corner.length; } public boolean pointInside(float x, float y) { float newy = (float) (Math.sin(angle) * (y - center.y) + Math.cos(angle) * (x - center.x)); float newx = (float) (Math.cos(angle) * (x - center.x) - Math.sin(angle) * (y - center.y)); return (newy > center.y - (getHeight() / 2)) && (newy < center.y + (getHeight() / 2)) && (newx > center.x - (getWidth() / 2)) && (newx < center.x + (getWidth() / 2)); } public boolean pointInside(Vector2D v) { return pointInside(v.x,v.y); } public ArrayList<Vector2D> getCollsionPoints(OBB2D b) { collisionPoints.clear(); for(int i = 0; i < corner.length; ++i) { if(b.pointInside(corner[i])) { collisionPoints.add(corner[i]); } } for(int i = 0; i < b.corner.length; ++i) { if(pointInside(b.corner[i])) { collisionPoints.add(b.corner[i]); } } return collisionPoints; } }; What could be wrong? When I getCollisionPoints for 2 OBBs I know are penetrating, it returns no points. Thanks

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  • Point of contact of 2 OBBs?

    - by Milo
    I'm working on the physics for my GTA2-like game so I can learn more about game physics. The collision detection and resolution are working great. I'm now just unsure how to compute the point of contact when I hit a wall. Here is my OBB class: public class OBB2D { private Vector2D projVec = new Vector2D(); private static Vector2D projAVec = new Vector2D(); private static Vector2D projBVec = new Vector2D(); private static Vector2D tempNormal = new Vector2D(); private Vector2D deltaVec = new Vector2D(); // Corners of the box, where 0 is the lower left. private Vector2D corner[] = new Vector2D[4]; private Vector2D center = new Vector2D(); private Vector2D extents = new Vector2D(); private RectF boundingRect = new RectF(); private float angle; //Two edges of the box extended away from corner[0]. private Vector2D axis[] = new Vector2D[2]; private double origin[] = new double[2]; public OBB2D(float centerx, float centery, float w, float h, float angle) { for(int i = 0; i < corner.length; ++i) { corner[i] = new Vector2D(); } for(int i = 0; i < axis.length; ++i) { axis[i] = new Vector2D(); } set(centerx,centery,w,h,angle); } public OBB2D(float left, float top, float width, float height) { for(int i = 0; i < corner.length; ++i) { corner[i] = new Vector2D(); } for(int i = 0; i < axis.length; ++i) { axis[i] = new Vector2D(); } set(left + (width / 2), top + (height / 2),width,height,0.0f); } public void set(float centerx,float centery,float w, float h,float angle) { float vxx = (float)Math.cos(angle); float vxy = (float)Math.sin(angle); float vyx = (float)-Math.sin(angle); float vyy = (float)Math.cos(angle); vxx *= w / 2; vxy *= (w / 2); vyx *= (h / 2); vyy *= (h / 2); corner[0].x = centerx - vxx - vyx; corner[0].y = centery - vxy - vyy; corner[1].x = centerx + vxx - vyx; corner[1].y = centery + vxy - vyy; corner[2].x = centerx + vxx + vyx; corner[2].y = centery + vxy + vyy; corner[3].x = centerx - vxx + vyx; corner[3].y = centery - vxy + vyy; this.center.x = centerx; this.center.y = centery; this.angle = angle; computeAxes(); extents.x = w / 2; extents.y = h / 2; computeBoundingRect(); } //Updates the axes after the corners move. Assumes the //corners actually form a rectangle. private void computeAxes() { axis[0].x = corner[1].x - corner[0].x; axis[0].y = corner[1].y - corner[0].y; axis[1].x = corner[3].x - corner[0].x; axis[1].y = corner[3].y - corner[0].y; // Make the length of each axis 1/edge length so we know any // dot product must be less than 1 to fall within the edge. for (int a = 0; a < axis.length; ++a) { float l = axis[a].length(); float ll = l * l; axis[a].x = axis[a].x / ll; axis[a].y = axis[a].y / ll; origin[a] = corner[0].dot(axis[a]); } } public void computeBoundingRect() { boundingRect.left = JMath.min(JMath.min(corner[0].x, corner[3].x), JMath.min(corner[1].x, corner[2].x)); boundingRect.top = JMath.min(JMath.min(corner[0].y, corner[1].y),JMath.min(corner[2].y, corner[3].y)); boundingRect.right = JMath.max(JMath.max(corner[1].x, corner[2].x), JMath.max(corner[0].x, corner[3].x)); boundingRect.bottom = JMath.max(JMath.max(corner[2].y, corner[3].y),JMath.max(corner[0].y, corner[1].y)); } public void set(RectF rect) { set(rect.centerX(),rect.centerY(),rect.width(),rect.height(),0.0f); } // Returns true if other overlaps one dimension of this. private boolean overlaps1Way(OBB2D other) { for (int a = 0; a < axis.length; ++a) { double t = other.corner[0].dot(axis[a]); // Find the extent of box 2 on axis a double tMin = t; double tMax = t; for (int c = 1; c < corner.length; ++c) { t = other.corner[c].dot(axis[a]); if (t < tMin) { tMin = t; } else if (t > tMax) { tMax = t; } } // We have to subtract off the origin // See if [tMin, tMax] intersects [0, 1] if ((tMin > 1 + origin[a]) || (tMax < origin[a])) { // There was no intersection along this dimension; // the boxes cannot possibly overlap. return false; } } // There was no dimension along which there is no intersection. // Therefore the boxes overlap. return true; } public void moveTo(float centerx, float centery) { float cx,cy; cx = center.x; cy = center.y; deltaVec.x = centerx - cx; deltaVec.y = centery - cy; for (int c = 0; c < 4; ++c) { corner[c].x += deltaVec.x; corner[c].y += deltaVec.y; } boundingRect.left += deltaVec.x; boundingRect.top += deltaVec.y; boundingRect.right += deltaVec.x; boundingRect.bottom += deltaVec.y; this.center.x = centerx; this.center.y = centery; computeAxes(); } // Returns true if the intersection of the boxes is non-empty. public boolean overlaps(OBB2D other) { if(right() < other.left()) { return false; } if(bottom() < other.top()) { return false; } if(left() > other.right()) { return false; } if(top() > other.bottom()) { return false; } if(other.getAngle() == 0.0f && getAngle() == 0.0f) { return true; } return overlaps1Way(other) && other.overlaps1Way(this); } public Vector2D getCenter() { return center; } public float getWidth() { return extents.x * 2; } public float getHeight() { return extents.y * 2; } public void setAngle(float angle) { set(center.x,center.y,getWidth(),getHeight(),angle); } public float getAngle() { return angle; } public void setSize(float w,float h) { set(center.x,center.y,w,h,angle); } public float left() { return boundingRect.left; } public float right() { return boundingRect.right; } public float bottom() { return boundingRect.bottom; } public float top() { return boundingRect.top; } public RectF getBoundingRect() { return boundingRect; } public boolean overlaps(float left, float top, float right, float bottom) { if(right() < left) { return false; } if(bottom() < top) { return false; } if(left() > right) { return false; } if(top() > bottom) { return false; } return true; } public static float distance(float ax, float ay,float bx, float by) { if (ax < bx) return bx - ay; else return ax - by; } public Vector2D project(float ax, float ay) { projVec.x = Float.MAX_VALUE; projVec.y = Float.MIN_VALUE; for (int i = 0; i < corner.length; ++i) { float dot = Vector2D.dot(corner[i].x,corner[i].y,ax,ay); projVec.x = JMath.min(dot, projVec.x); projVec.y = JMath.max(dot, projVec.y); } return projVec; } public Vector2D getCorner(int c) { return corner[c]; } public int getNumCorners() { return corner.length; } public static float collisionResponse(OBB2D a, OBB2D b, Vector2D outNormal) { float depth = Float.MAX_VALUE; for (int i = 0; i < a.getNumCorners() + b.getNumCorners(); ++i) { Vector2D edgeA; Vector2D edgeB; if(i >= a.getNumCorners()) { edgeA = b.getCorner((i + b.getNumCorners() - 1) % b.getNumCorners()); edgeB = b.getCorner(i % b.getNumCorners()); } else { edgeA = a.getCorner((i + a.getNumCorners() - 1) % a.getNumCorners()); edgeB = a.getCorner(i % a.getNumCorners()); } tempNormal.x = edgeB.x -edgeA.x; tempNormal.y = edgeB.y - edgeA.y; tempNormal.normalize(); projAVec.equals(a.project(tempNormal.x,tempNormal.y)); projBVec.equals(b.project(tempNormal.x,tempNormal.y)); float distance = OBB2D.distance(projAVec.x, projAVec.y,projBVec.x,projBVec.y); if (distance > 0.0f) { return 0.0f; } else { float d = Math.abs(distance); if (d < depth) { depth = d; outNormal.equals(tempNormal); } } } float dx,dy; dx = b.getCenter().x - a.getCenter().x; dy = b.getCenter().y - a.getCenter().y; float dot = Vector2D.dot(dx,dy,outNormal.x,outNormal.y); if(dot > 0) { outNormal.x = -outNormal.x; outNormal.y = -outNormal.y; } return depth; } public Vector2D getMoveDeltaVec() { return deltaVec; } }; Thanks!

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  • Point sample opacity/alpha in Adobe Photoshop?

    - by Josh
    I opened a PNG containing an alpha channel in Photoshop and wanted to get the opacity / alpha of a given point in the PNG file, so that I could match that opacity in a new photoshop layer. How can I do this? is there any way to get an alpha value at a point the way the color sample tool gives RGB values at a given point?

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  • Is an Ethernet point to point connection without a switch real time capable?

    - by funksoulbrother
    In automation and control, it is commonly stated that ethernet can't be used as a bus because it is not real time capable due to packet collisions. If important control packets collide, they often can't keep the hard real time conditions needed for control. But what if I have a single point to point connection with Ethernet, no switch in between? To be more precise, I have an FPGA board with a giga-Ethernet port that is connected directly to my control PC. I think the benefits of giga Ethernet over CAN or USB for a p2p connection are huge, especially for high sampling rates and lots of data generation on the FPGA board. Am I correct that with a point to point connection there can't be any packet collisions and therefore a real time environment is given even with ethernet? Thanks in advance! ~fsb

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  • Is an Ethernet point to point connection without a switch real time capable?

    - by funksoulbrother
    In automation and control, it is commonly stated that ethernet can't be used as a bus because it is not real time capable due to packet collisions. If important control packets collide, they often can't keep the hard real time conditions needed for control. But what if I have a single point to point connection with Ethernet, no switch in between? To be more precise, I have an FPGA board with a giga-Ethernet port that is connected directly to my control PC. I think the benefits of giga Ethernet over CAN or USB for a p2p connection are huge, especially for high sampling rates and lots of data generation on the FPGA board. Am I correct that with a point to point connection there can't be any packet collisions and therefore a real time environment is given even with ethernet? Thanks in advance! ~fsb

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  • Difference between indoor and outdoor WiFi Access Points

    - by aaron-cook
    Does anyone know if there is an operational difference between what is classified as an 'indoor' wifi access point and an 'outdoor' wifi access point. I'm speaking specifically to its operation rather than things like whether its enclosure is weather proof or not. And I'm also referring to the access point itself as opposed to the antenna used.

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  • outlook security alert after adding a second wireless access point to the network

    - by Mark
    Just added a Netgear WG103 Wireless Access Point in our conference room to allow visitors to access the internet through out internal network. When switched on visitors can connect to the intenet and everything works fine. Except, when the Access Point is switched on, normal users of the network get a Security Alert when they try to start Outlook 2007. The Security Alert is the same as the one shown in question 148526 asked by desiny back in June 2010 (http://serverfault.com/questions/148526/outlook-security-alert-following-exchange-2007-upgrade-to-sp2) rather than "autodiscover.ad.unc.edu" my security alert references our "Remote.server.org.uk". If I view the certificate it relates to "Netgear HTTPS:....", but the only Netgear equipment we have is the new Access Point installed in the conference room. If the Access Point is not switched on we do not get the Security Alert. At first I thought it was because we had selected "WPA-PSK & WPA2-PSK" Network Authentication Type but it continues to occur even if we opt for "Shared Key" WEP Data Encryption. I do not understand why adding a Netgear Wireless Access point would cause Outlook to issue a Security Alert when users try to read their email. Does anyone know what I have to do to get rid of the Security Alert? Thanks in advance for reading this and helping me out.

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  • Set custom mount point and mount options for USB stick

    - by kayahr
    Hello, I have an USB stick which contains private stuff like the SSH key. I want to mount this stick to my own home directory with 0700 permissions. Currently I do this with this line in /etc/fstab: LABEL=KAYSTICK /home/k/.kaystick auto rw,user,noauto,umask=077,fmask=177 0 0 This works great but there is one minor problem: In Nautilus (The Gnome file manager) the mount point ".kaystick" is displayed. I guess Nautilus simply scans the /etc/fstab file and displays everything it finds there. This mount point is pretty useless because it can't be clicked when the device is not present and it can't be clicked when the device is present (Because then it is already mounted). I know this is a really minor problem because I could simply ignore it but I'm a perfectionist and so I want to get rid of this useless mount point in Nautilus. Is there another way to customize the mount point and mount options for a specific USB device? Maybe it can be configured in udev? If yes, how?

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  • Do I need a Point and a Vector object? Or just using a Vector object to represent a Point is ok?

    - by JCM
    Structuring the components of an engine that I am developing along with a friend (learning purposes), I came to this doubt. Initially we had a Point constructor, like the following: var Point = function( x, y ) { this.x = x; this.y = y; }; But them we started to add some Vector math to it, and them decided to rename it to Vector2d. But now, some methods are a bit confusing (at least in my opinion), such as the following, which is used to make a line: //before the renaming of Point to Vector2, the parameters were startingPoint and endingPoint Geometry.Line = function( startingVector, endingVector ) { //... }; I should make a specific constructor for the Point object, or there are no problems in defining a point as a vector? I know a vector have magnitude and direction, but I see so many people using a vector to just represent the position of an object.

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  • 2 Days of Share &amp; Point

    - by Mark Rackley
    Groovy man… SharePoint Saturday Ozarks is back for 2010, bigger and better than before. Join us for a far out time and learn more about SharePoint in one day than you could in a year from the man… Yes! SharePoint Saturday Ozarks is back! SharePoint Saturday Ozarks is the largest SharePoint conference in Arkansas, Southern Missouri, and the very north east tip of Oklahoma. Last year we had a great turn out with 20 speakers, 5 MVPs, and attendees coming from Arkansas, Texas, Oklahoma, Missouri, Kansas, Nebraska, Indiana, Ohio, Alabama, Michigan, and Washington. Hey Man… what’s SharePoint Saturday anyway? Sounds like a conspiracy man… Not to worry, SharePoint Saturday is not an arm of the government bent on mind control or any attempt what-so-ever to bring you down man. SharePoint Saturday is grass roots effort started by Michael Lotter (http://www.sharepointsaturday.org/pages/about.aspx). It is a FREE one day event where the best SharePoint speakers gather to present their love, hatred, and frustrations of SharePoint to those lucky individuals who attend. Lessons are learned, contacts are made, prizes are won, food is eaten, assorted beverages are consumed until wee hours of the morning. SharePoint Saturday started with just a few sporadic one day events here and there. However, over the past year SharePoint Saturday has exploded and it’s hard to find a weekend where there is NOT a SharePoint Saturday event happing in some corner of the globe. There are even occasions where there are two SharePoint Saturdays on the same day! Many people are pleasantly surprised at the caliber of speakers at these SharePoint Saturday events. For the most part, these speakers are more eloquent, practiced, and practical than those speakers you find at the major multi-day conferences. These guys aren’t even paid to speak.. they do it out of love man… SharePoint Saturday Ozarks 2009 Alumni We had a star studded cast last year with many returning this year! Just check out the fun that they had… John Ferringer – Admin rockstar… I can still sense the awesomeness   SharePoint poster children Mike Watson & Laura Rogers     Lori Gowin spreading the SharePoint Love Eric Shupps is a little bit country and a little bit rock and roll       Cathy Dew, Sean McDonough, and JD Wade relaxing between gigs Actually, you can see real photos from last year’s SharePoint Saturday ozarks here:  picasaweb.google.com/mrackley/SharePointSaturdayOzarks#    What’s new for SharePoint Saturday Ozarks 2010 SharePoint Saturday Ozarks 2010 will totally blow your mind man. We’re getting the band back to together with many returning speakers and few new faces. Joel Oleson will be speaking this year, maybe he’ll grace us with his song stylings. Sadly, once again, Andrew Connell will not be able to attend SharePoint Saturday Ozarks, however he did feel the need to show his support in his own way. Prizes this year currently include books, software, a Zune HD, and much more! Wait Man… You said 2 days? I thought it was a one day event? Correct you are my herbal smelling friend… SharePoint Saturday Ozarks 2010 will spread the love an additional day this year. The first day will be all about the SharePoint love, on day 2 we will be taking a leisurely float down the Buffalo National River for those interested in a truly unique experience (no banjos allowed please).   Here are the details: WHAT 4 – 5 hour float down the Buffalo National River WHEN & WHERE Sunday June 13th. We will be leaving at 10am from the Parking Lot of: Gordon’s Motel & Canoe Rental Old Highway 7 Jasper, AR 72641 (870) 446-5252 Jasper is about 30 minutes south of Harrison, AR on Highway 7 South. You are responsible for bumming a ride to/from Gordon’s Motel, but they will be shuttling us to/from the river and providing canoes and a boxed lunch. WHAT ELSE? The float trip is dependent on the weather of course, we won’t be floating down the river in a thunderstorm, however I planned SPS Ozarks around a time of year ideal for floating. We aren’t talking class 5 rapids here, you don’t need any real skill, but you need to be okay with possibly tipping your canoe over once or twice. You can bring your own assorted beverages with you, but glass containers are not allowed on the river. I suggest a small cooler with extra snacks and drinks. Also bring clothing you can get wet in (these SharePoint people can get ornery). HOW DO I SIGN UP? When you register for SharePoint Saturday Ozarks, you will have the option to also sign up for the float trip. Seats are limited though! If you do not intend to go, please do not take someone else’s place.  The cost for the float trip will be about $35 dollars per person (which you are responsible for unless we find a sponsor). The price includes shuttle to/from river, canoe, life jackets, paddles, and boxed lunch. Far out man… how do I register??? You can register for SharePoint Saturday Ozarks by going to http://spsozarks.eventbrite.com/ We are limited to 200 people for the conference and 50 people for the float trip, so register today before we are sold out. Lodging for SharePoint Saturday Ozarks will once again take place at the Hotel Seville: Annex Suites are available for $103.20 This is So Groovy.. How can I help? I’m glad you asked! We are still looking for a few sponsors and one or two more speakers. If you are interested please let me know!  You can find out more information at http://www.sharepointsaturday.org/ozarks Hey… wait a minute…. what exactly IS SharePoint man??? Come to SharePoint Saturday Ozarks and find out!!  See you guys there!

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  • Point subdomain to another web hosting

    - by zulhfreelancer
    I buy a domain from GoDaddy. Let's call this domain as abc.com. I've a hosting account on web hosting A with abc.com as my primary domain. I created a sub-domain pic.abc.com and I wish it to be pointed to my new hosting account. This web hosting B also use abc.com as the primary domain. The main purpose of doing this because I only want to use web hosting B to host my pic.abc.com contents. That's all. Other content from *.abc.com and abc.com will be remain in web hosting A. How to do this? Note 1: I try to add pic.abc.com as an add-on domain in my web hosting B account. Unfortunately, I couldn't do that. Note 2: I also try to use URL forwarding method using DNS management service like DNS Social. It doesn't work. Note 3: I'm using WordPress on the pic.abc.com site. Both web hosting A and B running cPanel - Apache servers (shared hosting). Thanks in advance!

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  • My laptop can not access internet after setup bridge with wired NIC and wireless NIC

    - by Victor S
    I setup a bridge using wired NIC and wireless NIC in order to make wireless NIC as a Wi-Fi AP to share wired internet access, after setup successfully, the Wi-Fi AP works as my expectation, but my laptop can not access internet, please give me a hand. Thanks. My hostapd.conf $ cat hostapd.conf interface=wlan0 bridge=br0 driver=nl80211 ssid=myAP hw_mode=g channel=11 dtim_period=1 rts_threshold=2347 fragm_threshold=2346 macaddr_acl=0 auth_algs=3 ieee80211n=0 wpa=3 wpa_passphrase=PassWord wpa_key_mgmt=WPA-PSK wpa_pairwise=TKIP rsn_pairwise=CCMP Setup steps: $ sudo killall hostapd hostapd: no process found $ sudo hostapd -B hostapd.conf Configuration file: hostapd.conf Using interface wlan0 with hwaddr 00:26:5e:e8:4f:8e and ssid 'myAP' $ sudo brctl addbr br0 device br0 already exists; can't create bridge with the same name $ sudo ifconfig eth0 0.0.0.0 up $ sudo ifconfig wlan0 0.0.0.0 up $ sudo brctl addif br0 eth0 $ sudo brctl addif br0 wlan0 device wlan0 is already a member of a bridge; can't enslave it to bridge br0. $ sudo ifconfig br0 192.168.1.110 netmask 255.255.255.0 $ sudo route add default gw 192.168.1.1

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  • How to Turn Your Ubuntu Laptop into a Wireless Access Point

    - by Chris Hoffman
    If you have a single wired Internet connection – say, in a hotel room – you can create an ad-hoc wireless network with Ubuntu and share the Internet connection among multiple devices. Ubuntu includes an easy, graphical setup tool. Unfortunately, there are some limitations. Some devices may not support ad-hoc wireless networks and Ubuntu can only create wireless hotspots with weak WEP encryption, not strong WPA encryption. HTG Explains: What Is RSS and How Can I Benefit From Using It? HTG Explains: Why You Only Have to Wipe a Disk Once to Erase It HTG Explains: Learn How Websites Are Tracking You Online

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