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  • Can't update nor install anything due to "unrecoverable fatal error"

    - by Dunya Cengiz
    I haven't done any changes to my Ubuntu but since yesterday I can't download anything from Software Center nor can I update. All the time I get an error. I don't know why is this happening. I am currently using Ubuntu 12.04. Important part of the message from image: dpkg: unrecoverable fatal error, aborting: reading files list for package 'linux-headers-3.2.0-24': input/output error Error in function:

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  • How do I use D3DXVec3Unproject with D3D11?

    - by Miguel P
    I'm having a small issue with D3DXVec3Unproject. I'm currently using Direct3D 11 and not 10, and the signature for this function is: D3DXVECTOR3 *pOut, CONST D3DXVECTOR3 *pV, CONST D3D10_VIEWPORT *pViewport, CONST D3DXMATRIX *pProjection, CONST D3DXMATRIX *pView, CONST D3DXMATRIX *pWorld As you may have noticed, it requires a D3D10_VIEWPORT, and I'm using a Direct3D 11 viewport, D3D11_VIEWPORT. Do you have any ideas how I can use D3DXVec3Unproject with Direct3D 11?

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  • What are known approaches to graphing algebraic expressions?

    - by jeremynealbrown
    I am planning to build an expression parser that will be used to graph algebraic functions ( think TI-83 ) with JavaScript. Functions will take the form of f(x)= Aside from typical operators such as: + - * / ^ I'd also like to add support for inline functions such as: sin(), cos(), log() and random(). I have looked at implementing the Shunting Yard algorithm for parsing expressions, but it does not look like an efficient approach to evaluating a function with a hundreds or thousands of inputs. What other known algorithms exist for this task?

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  • Oracle E-Business Suite Tip : SQL Tracing

    - by Giri Mandalika
    Issue: Attempts to enable SQL tracing from concurrent request form fails with error: Function not available to this responsibility. Change Responsibilities or contact your System Administrator Resolution: Switch responsibility to "System Administrator". Navigate to System - Profiles, and query for "%Diagnostics% ("Utilities : Diagnostics")". Once found the profile, change its value to "Yes". Restart web browser and try enabling SQL trace again.

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  • Deciding between obj->func() and func(obj)

    - by GSto
    I was thinking about this when I was starting to set up some code for a new project: are there any rules of thumb for when a method should be part of an object, and when it should be a stand alone function that takes an object as a parameter? EDIT: as pointed out in a comment, this can depend on language. I was working in C++ when it came to mind, though I'm this is an issue across a number of languages (and would still love to see answers that pertain to them).

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  • Drawing a texture at the end of a trace (crosshair?) UDK

    - by Dave Voyles
    I'm trying to draw a crosshair at the end of my trace. If my crosshair does not hit a pawn or static mesh (ex, just a skybox) then the crosshair stays locked on a certain point at that actor - I want to say its origin. Ex: Run across a pawn, then it turns yellow and stays on that pawn. If it runs across the skybox, then it stays at one point on the box. Weird? How can I get my crosshair to stay consistent? I've included two images for reference, to help illustrate. Note: The wrench is actually my crosshair. The "X" is just a debug crosshair. Ignore that. /// Image 1 /// /// Image 2 /// /*************************************************************************** * Draws the crosshair ***************************************************************************/ function bool CheckCrosshairOnFriendly() { local float CrosshairSize; local vector HitLocation, HitNormal, StartTrace, EndTrace, ScreenPos; local actor HitActor; local MyWeapon W; local Pawn MyPawnOwner; /** Sets the PawnOwner */ MyPawnOwner = Pawn(PlayerOwner.ViewTarget); /** Sets the Weapon */ W = MyWeapon(MyPawnOwner.Weapon); /** If we don't have an owner, then get out of the function */ if ( MyPawnOwner == None ) { return false; } /** If we have a weapon... */ if ( W != None) { /** Values for the trace */ StartTrace = W.InstantFireStartTrace(); EndTrace = StartTrace + W.MaxRange() * vector(PlayerOwner.Rotation); HitActor = MyPawnOwner.Trace(HitLocation, HitNormal, EndTrace, StartTrace, true, vect(0,0,0),, TRACEFLAG_Bullet); DrawDebugLine(StartTrace, EndTrace, 100,100,100,); /** Projection for the crosshair to convert 3d coords into 2d */ ScreenPos = Canvas.Project(HitLocation); /** If we haven't hit any actors... */ if ( Pawn(HitActor) == None ) { HitActor = (HitActor == None) ? None : Pawn(HitActor.Base); } } /** If our trace hits a pawn... */ if ((Pawn(HitActor) == None)) { /** Draws the crosshair for no one - Grey*/ CrosshairSize = 28 * (Canvas.ClipY / 768) * (Canvas.ClipX /1024); Canvas.SetDrawColor(100,100,128,255); Canvas.SetPos(ScreenPos.X - (CrosshairSize * 0.5f), ScreenPos.Y -(CrosshairSize * 0.5f)); Canvas.DrawTile(class'UTHUD'.default.AltHudTexture, CrosshairSize, CrosshairSize, 600, 262, 28, 27); return false; } /** Draws the crosshair for friendlies - Yellow */ CrosshairSize = 28 * (Canvas.ClipY / 768) * (Canvas.ClipX /1024); Canvas.SetDrawColor(255,255,128,255); Canvas.SetPos(ScreenPos.X - (CrosshairSize * 0.5f), ScreenPos.Y -(CrosshairSize * 0.5f)); Canvas.DrawTile(class'UTHUD'.default.AltHudTexture, CrosshairSize, CrosshairSize, 600, 262, 28, 27); return true; }

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  • Box2D relations

    - by Valentino Ru
    As far as I know, the unit in Box2D is meters. When I use Box2D in Processing with JBox2D, I set the "world size" as the window size specified in the setup(). Now I'm wondering if there is any function that scales down the world. For example, how can I simulate the throw of tennis ball within a room, without using a window of only 5 x 5 pixels? Additionally, is there any good documentation like the Java API?

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  • How to Overcome or fix MIXED_DML_OPERATION error in Salesforce APEX without future method ?

    - by sathya
    How to Overcome or fix MIXED_DML_OPERATION error in Salesforce APEX without future method ?MIXED_DML_OPERATION :-one of the worst issues we have ever faced :)While trying to perform DML operation on a setup object and non-setup object in a single action you will face this error.Following are the solutions I tried and the final one worked out :-1. perform the 1st objects DML on normal apex method. Then Call the 2nd objects DML through a future method.    Drawback :- You cant get a response from the future method as its context is different and because its executing asynchronously and that its static.2. Tried the following option but it didnt work :-    1. perform the dml operation on the normal apex method.    2. tried calling the 2nd dml from trigger thinking that it would be in a different context. But it didnt work.    3. Some suggestions were given in some blogs that we could try System.runas()   Unfortunately that works only for test class.   4. Finally achieved it with response synchronously through the following solution :-    a. Created 2 apex:commandbuttons :-        1. <apex:commandButton value="Save and Send Activation Email" action="{!CreateContact}"  rerender="junkpanel" oncomplete="callSimulateUserSave()">            Note :- Oncomplete will not work if you dont have a rerender attribute. So just try refreshing a junk panel.        2. <apex:commandButton value="SimulateUserSave" id="SimulateUserSave" action="{!SaveUser}"  style="display:none;margin-left:5px;"/>        Have a junk panel as well just for rerendering  :-        <apex:outputPanel id="junkpanel"></apex:outputPanel>    b. Created this javascript function which is called from first button's oncomplete and clicks the second button :-                function callSimulateUserSave()                {                    // Specify the id of the button that needs to be clicked. This id is based on the Apex Component Hierarchy.                    // You will not get this value if you dont have the id attribute in the button which needs to be clicked from javascript                    // If you have any doubt in getting this value. Just hover over the button using Chrome developer tools to get the id.                    // But it will show like theForm:SimulateUserSave but you need to replace the colon with a dot here.                    // Note :- I have given display:none in the style of the second button to make sure that, it is not visible for the user.                    var mybtn=document.getElementById('{!$Component.theForm.SimulateUserSave}');                                    mybtn.click();                }    c. Apex Methods CreateContact and SaveUser are the pagereference methods which contains the code to create contact and user respectively.       After inserting the user inside the second apex method you can just set some public Properties in the page,        for ex:- created userid to get the user details and display in the page to show the acknowledgement to the users that the User is created.

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  • Updatable columnstore index, sp_spaceused and sys.partitions

    - by Michael Zilberstein
    Columnstore index in SQL Server 2014 contains 2 new important features: it can be clustered and it is updateable. So I decided to play with both. As a “control group” I’ve taken my old columnstore index demo from one of the ISUG (Israeli SQL Server Usergroup) sessions. The script itself isn’t important – it creates partition function with 7 partitions (actually 8 but one remains empty), table on it and populates the table with 63 million rows – 9 million in each partition. So I used the same script...(read more)

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  • What problems can arise from emulating concepts from another languages?

    - by Vandell
    I've read many times on the web that if your language doesn't support some concept, for example, object orientation, or maybe function calls, and it's considered a good practice in this other context, you should do it. The only problem I can see now is that other programmers may find your code too different than the usual, making it hard for them to program. What other problems do you think may arise from this?

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  • Organization &amp; Architecture UNISA Studies &ndash; Chap 4

    - by MarkPearl
    Learning Outcomes Explain the characteristics of memory systems Describe the memory hierarchy Discuss cache memory principles Discuss issues relevant to cache design Describe the cache organization of the Pentium Computer Memory Systems There are key characteristics of memory… Location – internal or external Capacity – expressed in terms of bytes Unit of Transfer – the number of bits read out of or written into memory at a time Access Method – sequential, direct, random or associative From a users perspective the two most important characteristics of memory are… Capacity Performance – access time, memory cycle time, transfer rate The trade off for memory happens along three axis… Faster access time, greater cost per bit Greater capacity, smaller cost per bit Greater capacity, slower access time This leads to people using a tiered approach in their use of memory   As one goes down the hierarchy, the following occurs… Decreasing cost per bit Increasing capacity Increasing access time Decreasing frequency of access of the memory by the processor The use of two levels of memory to reduce average access time works in principle, but only if conditions 1 to 4 apply. A variety of technologies exist that allow us to accomplish this. Thus it is possible to organize data across the hierarchy such that the percentage of accesses to each successively lower level is substantially less than that of the level above. A portion of main memory can be used as a buffer to hold data temporarily that is to be read out to disk. This is sometimes referred to as a disk cache and improves performance in two ways… Disk writes are clustered. Instead of many small transfers of data, we have a few large transfers of data. This improves disk performance and minimizes processor involvement. Some data designed for write-out may be referenced by a program before the next dump to disk. In that case the data is retrieved rapidly from the software cache rather than slowly from disk. Cache Memory Principles Cache memory is substantially faster than main memory. A caching system works as follows.. When a processor attempts to read a word of memory, a check is made to see if this in in cache memory… If it is, the data is supplied, If it is not in the cache, a block of main memory, consisting of a fixed number of words is loaded to the cache. Because of the phenomenon of locality of references, when a block of data is fetched into the cache, it is likely that there will be future references to that same memory location or to other words in the block. Elements of Cache Design While there are a large number of cache implementations, there are a few basic design elements that serve to classify and differentiate cache architectures… Cache Addresses Cache Size Mapping Function Replacement Algorithm Write Policy Line Size Number of Caches Cache Addresses Almost all non-embedded processors support virtual memory. Virtual memory in essence allows a program to address memory from a logical point of view without needing to worry about the amount of physical memory available. When virtual addresses are used the designer may choose to place the cache between the MMU (memory management unit) and the processor or between the MMU and main memory. The disadvantage of virtual memory is that most virtual memory systems supply each application with the same virtual memory address space (each application sees virtual memory starting at memory address 0), which means the cache memory must be completely flushed with each application context switch or extra bits must be added to each line of the cache to identify which virtual address space the address refers to. Cache Size We would like the size of the cache to be small enough so that the overall average cost per bit is close to that of main memory alone and large enough so that the overall average access time is close to that of the cache alone. Also, larger caches are slightly slower than smaller ones. Mapping Function Because there are fewer cache lines than main memory blocks, an algorithm is needed for mapping main memory blocks into cache lines. The choice of mapping function dictates how the cache is organized. Three techniques can be used… Direct – simplest technique, maps each block of main memory into only one possible cache line Associative – Each main memory block to be loaded into any line of the cache Set Associative – exhibits the strengths of both the direct and associative approaches while reducing their disadvantages For detailed explanations of each approach – read the text book (page 148 – 154) Replacement Algorithm For associative and set associating mapping a replacement algorithm is needed to determine which of the existing blocks in the cache must be replaced by a new block. There are four common approaches… LRU (Least recently used) FIFO (First in first out) LFU (Least frequently used) Random selection Write Policy When a block resident in the cache is to be replaced, there are two cases to consider If no writes to that block have happened in the cache – discard it If a write has occurred, a process needs to be initiated where the changes in the cache are propagated back to the main memory. There are several approaches to achieve this including… Write Through – all writes to the cache are done to the main memory as well at the point of the change Write Back – when a block is replaced, all dirty bits are written back to main memory The problem is complicated when we have multiple caches, there are techniques to accommodate for this but I have not summarized them. Line Size When a block of data is retrieved and placed in the cache, not only the desired word but also some number of adjacent words are retrieved. As the block size increases from very small to larger sizes, the hit ratio will at first increase because of the principle of locality, which states that the data in the vicinity of a referenced word are likely to be referenced in the near future. As the block size increases, more useful data are brought into cache. The hit ratio will begin to decrease as the block becomes even bigger and the probability of using the newly fetched information becomes less than the probability of using the newly fetched information that has to be replaced. Two specific effects come into play… Larger blocks reduce the number of blocks that fit into a cache. Because each block fetch overwrites older cache contents, a small number of blocks results in data being overwritten shortly after they are fetched. As a block becomes larger, each additional word is farther from the requested word and therefore less likely to be needed in the near future. The relationship between block size and hit ratio is complex, and no set approach is judged to be the best in all circumstances.   Pentium 4 and ARM cache organizations The processor core consists of four major components: Fetch/decode unit – fetches program instruction in order from the L2 cache, decodes these into a series of micro-operations, and stores the results in the L2 instruction cache Out-of-order execution logic – Schedules execution of the micro-operations subject to data dependencies and resource availability – thus micro-operations may be scheduled for execution in a different order than they were fetched from the instruction stream. As time permits, this unit schedules speculative execution of micro-operations that may be required in the future Execution units – These units execute micro-operations, fetching the required data from the L1 data cache and temporarily storing results in registers Memory subsystem – This unit includes the L2 and L3 caches and the system bus, which is used to access main memory when the L1 and L2 caches have a cache miss and to access the system I/O resources

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  • Hashing 3D position into 2D position

    - by notabene
    I am doing volumetric raycasting and curently working on depth jitter. I have 3D position on ray and want to sample 2D noise texture to jitter the depth. Function for converting (or hashing) 3D position to 2D have to produce absolutely different numbers for a little changes (especialy because i am sampling in texture space so sample values differs very very little) and have to be "shader-wise" - so forget about branches, cycles etc. I'm looking forward for yours nice and fast solutions.

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  • Use Expressions with LINQ to Entities

    - by EltonStoneman
    [Source: http://geekswithblogs.net/EltonStoneman] Recently I've been putting together a generic approach for paging the response from a WCF service. Paging changes the service signature, so it's not as simple as adding a behavior to an existing service in config, but the complexity of the paging is isolated in a generic base class. We're using the Entity Framework talking to SQL Server, so when we ask for a page using LINQ's .Take() method we get a nice efficient SQL query for just the rows we want, with minimal impact on SQL Server and network traffic. We use the maximum ID of the record returned as a high-water mark (rather than using .Skip() to go to the next record), so the approach caters for records being deleted between page requests. In the paged response we include a HasMorePages indicator, computed by comparing the max ID in the page of results to the max ID for the whole resultset - if the latter is bigger, then there are more pages. In some quick performance testing, the paged version of the service performed much more slowly than the unpaged version, which was unexpected. We narrowed it down to the code which gets the max ID for the full resultset - instead of building an efficient MAX() SQL query, EF was returning the whole resultset and then computing the max ID in the service layer. It's easy to reproduce - take this AdventureWorks query:             var context = new AdventureWorksEntities();             var query = from od in context.SalesOrderDetail                         where od.ModifiedDate >= modified                          && od.SalesOrderDetailID.CompareTo(id) > 0                         orderby od.SalesOrderDetailID                         select od;   We can find the maximum SalesOrderDetailID like this:             var maxIdEfficiently = query.Max(od => od.SalesOrderDetailID);   which produces our efficient MAX() SQL query. If we're doing this generically and we already have the ID function in a Func:             Func<SalesOrderDetail, int> idFunc = od => od.SalesOrderDetailID;             var maxIdInefficiently = query.Max(idFunc);   This fetches all the results from the query and then runs the Max() function in code. If you look at the difference in Reflector, the first call passes an Expression to the Max(), while the second call passes a Func. So it's an easy fix - wrap the Func in an Expression:             Expression<Func<SalesOrderDetail, int>> idExpression = od => od.SalesOrderDetailID;             var maxIdEfficientlyAgain = query.Max(idExpression);   - and we're back to running an efficient MAX() statement. Evidently the EF provider can dissect an Expression and build its equivalent in SQL, but it can't do that with Funcs.

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  • Sharing on Github

    - by Alan
    Over the past couple weeks I have gotten a lot of help from StackOverflow users on a project, and rather than keep the finished product to myself I wanted to share it unencumbered by licenses, but don't want there to be so much legwork during installation that users shy away from trying it. I am about to post it to Github and choosing public domain licensing. I would like to to be super simple for users to make use of and just FTP it up and go. That being said, do I need to make sure I remove things like the JQuery file, and other GPL / MIT licensed dependencies that I didn't write but that my code depends on? I haven't removed any copyright notices from the other code and all of it open source, it would just be nice if users could download everything at once while of course not trying to represent that I am the license holder of the dependencies. Inside my files are also some snippets, do those have to be externalized with installation instructions or can it be posted as is? Here is an example, my nav.php file is 115 lines long and I have these at the top: <script type="text/javascript" src="./js/ddaccordion.js"> /*********************************************** * Accordion Content script- (c) Dynamic Drive DHTML code library (www.dynamicdrive.com) * Visit http://www.dynamicDrive.com for hundreds of DHTML scripts * This notice must stay intact for legal use ***********************************************/ </script> <link href="css/admin.css" rel="stylesheet"> <script type="text/javascript"> ddaccordion.init({ headerclass: "submenuheader", //Shared CSS class name of headers group contentclass: "submenu", //Shared CSS class name of contents group revealtype: "click", //Reveal content when user clicks or onmouseover the header? Valid value: "click", "clickgo", or "mouseover" mouseoverdelay: 200, //if revealtype="mouseover", set delay in milliseconds before header expands onMouseover collapseprev: false, //Collapse previous content (so only one open at any time)? true/false defaultexpanded: [], //index of content(s) open by default [index1, index2, etc] [] denotes no content onemustopen: false, //Specify whether at least one header should be open always (so never all headers closed) animatedefault: false, //Should contents open by default be animated into view? persiststate: true, //persist state of opened contents within browser session? toggleclass: ["", ""], //Two CSS classes to be applied to the header when it's collapsed and expanded, respectively ["class1", "class2"] togglehtml: ["suffix", "<img src='./images/plus.gif' class='statusicon' />", "<img src='./images/minus.gif' class='statusicon' />"], //Additional HTML added to the header when it's collapsed and expanded, respectively ["position", "html1", "html2"] (see docs) animatespeed: "fast", //speed of animation: integer in milliseconds (ie: 200), or keywords "fast", "normal", or "slow" oninit:function(headers, expandedindices){ //custom code to run when headers have initalized //do nothing }, onopenclose:function(header, index, state, isuseractivated){ //custom code to run whenever a header is opened or closed //do nothing } }) </script>

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  • ASP.NET book for desktop programmer. [closed]

    - by RealityDysfunction
    Fellow programmers, I have been learning C# for a while now, but my ultimate goal is to develop ASP.NET applications. A few ASP.NET books I looked at either start with absolute basics...What is C#? What is a function...or Assume that I have developed web apps in other languages like PHP...I am looking for a book that is tailored for people who already know desktop programming but wish to learn ASP.NET. Did anybody come across such a book? Many Thanks.

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  • Build a view frustum from angles

    - by MulletDevil
    I have 4 angles, left, right, top & bottom. These angles are in degrees. They define the angle between the forward vector and the corresponding side. I am trying to use these to calculate the required values for Perseective Off Centre function found here http://docs.unity3d.com/Documentation/ScriptReference/Camera-projectionMatrix.html I tried doing (near plane-far plane) * Tan(angle) But that didn't give the correct results.

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  • Animate multiple entities

    - by Robert
    I'm trying to animate multiple(3) entities using one model(IQM format). It's working but performance is really bad because I'm calling animate function for each entity in my game loop (I think problem is there). What's the best way to animate multiple entities (with different animation ofc) in OpenGL? I think I can try build one VBO / entity for better performances but I don't think it's the best way to do it.

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  • Validate if aTextBox Value Start with a Specific Letter

    - by Vincent Maverick Durano
    In case you will be working on a page that needs to validate the first character of the TextBox entered by a user then here are two options that you can use: Option 1: Using an array   1: <asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server"> 2: <script type="text/javascript"> 3: function CheckFirstChar(o) { 4: var arr = ['A', 'B', 'C', 'D']; 5: if (o.value.length > 0) { 6: for (var i = 0; i < arr.length; i++) { 7: if (o.value.charAt(0) == arr[i]) { 8: alert('Valid'); 9: return true; 10: } 11: else { 12: alert('InValid'); 13: return false; 14: } 15: } 16: } 17: } 18: </script> 19: </asp:Content> 20: <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> 21: <asp:TextBox ID="TextBox1" runat="server" onblur="return CheckFirstChar(this);"></asp:TextBox> 22: </asp:Content>   The example above uses an array of string for storing the list of  characters that a TextBox value should start with. We then iterate to the array and compare the first character of TextBox value to see if it matches any characters from the array. Option 2: Using Regular Expression (Preferred way)   1: <asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server"> 2: <script type="text/javascript"> 3: function CheckFirstChar(o) { 4: pattern = /^(A|B|C|D)/; 5: if (!pattern.test(o.value)) { 6: alert('InValid'); 7: return false; 8: } else { 9: alert('Valid'); 10: return true; 11: } 12: } 13: </script> 14: </asp:Content> 15: <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> 16: <asp:TextBox ID="TextBox1" runat="server" onblur="return CheckFirstChar(this);"></asp:TextBox> 17: </asp:Content>   The example above uses regular expression with the pattern  /^(A|B|C|D)/. This will check if the TextBox value starts with A,B,C or D. Please note that it's case sensitive. If you want to allow lower case then you can alter the patter to this /^(A|B|C|D)/i. The i in the last part will cause a case-insensitive search.   That's it! I hope someone find this post useful!

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  • Delete button in Ubuntu One Notes

    - by Jean MC13
    For the whishlist... The 'delete button' in Ubuntu One Notes is exactly in the same place as the 'save' button. So I saved a long note, but as my finger clicked two times on the save button, the second click was on the 'delete' one ! Lost without return possible. <:-(( This annoying feature could easily be changed : - put the delete button in another place - before deleting : ask for confirmation - offer a way to cancel ('undelete' function)

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  • Improving Finance Department Productivity at BorgWarner

    Nigel Youell, Product Marketing Director, Enterprise Performance Management Applications at Oracle discusses with Mark Smith, Manager, Financial Reporting Systems at BorgWarner how using Oracle's Enterprise Performance Management System on top of SAP transactional systems at BorgWarner has made significant improvements in the productivity of it finance function and halved the time it takes for to close its books.

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  • When to use typedef?

    - by futlib
    I'm a bit confused about if and when I should use typedef in C++. I feel it's a balancing act between readability and clarity. Here's a code sample without any typedefs: int sum(std::vector<int>::const_iterator first, std::vector<int>::const_iterator last) { static std::map<std::tuple<std::vector<int>::const_iterator, std::vector<int>::const_iterator>, int> lookup_table; std::map<std::tuple<std::vector<int>::const_iterator, std::vector<int>::const_iterator>, int>::iterator lookup_it = lookup_table.find(lookup_key); if (lookup_it != lookup_table.end()) return lookup_it->second; ... } Pretty ugly IMO. So I'll add some typedefs within the function to make it look nicer: int sum(std::vector<int>::const_iterator first, std::vector<int>::const_iterator last) { typedef std::tuple<std::vector<int>::const_iterator, std::vector<int>::const_iterator> Lookup_key; typedef std::map<Lookup_key, int> Lookup_table; static Lookup_table lookup_table; Lookup_table::iterator lookup_it = lookup_table.find(lookup_key); if (lookup_it != lookup_table.end()) return lookup_it->second; ... } The code is still a bit clumsy, but I get rid of most nightmare material. But there's still the int vector iterators, this variant gets rid of those: typedef std::vector<int>::const_iterator Input_iterator; int sum(Input_iterator first, Input_iterator last) { typedef std::tuple<Input_iterator, Input_iterator> Lookup_key; typedef std::map<Lookup_key, int> Lookup_table; static Lookup_table lookup_table; Lookup_table::iterator lookup_it = lookup_table.find(lookup_key); if (lookup_it != lookup_table.end()) return lookup_it->second; ... } This looks clean, but is it still readable? When should I use a typedef? As soon as I have a nightmare type? As soon as it occurs more than once? Where should I put them? Should I use them in function signatures or keep them to the implementation?

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  • Any ideas on reducing lag in terrain generation?

    - by l5p4ngl312
    Ok so here's the deal. I've written an isometric engine that generates terrain based on camera values using 2D perlin noise. I planned on doing 3D but first I need to work out the lag issues I'm having. I will try to explain how I am doing this so that maybe someone can spot where I am going wrong. I know it should not be this laggy. There is the abstract class Block which right now just contains render(). BlockGrass, etc. extend this class and each has code in the render function to create a textured quad at the given position. Then there is the class Chunk which has the function Generate() and setBlocksInArea(). Generate uses 2D perlin noise to make a height map and stores the heights in a 2D array. It stores the positions of each block it generates in blockarray[x][y][z]. The chunks are 8x8x128. In the main game class there is a 3D array called blocksInArea. The blocks in this array are what gets rendered. When a chunk generates, it adds its blocks to this array at the correct index. It is like this so chunks can be saved to the hard drive (even though they aren't yet) but there can still be optimization with the rendering that you wouldn't have if you rendered each chunk separately. Here's where the laggy part comes in: When the camera moves to a new chunk, a row of chunks generates on the end of the axis that the camera moved on. But it still has to move the other chunks up/down in the blocksInArea (render) array. It does this by calculating the new position in the array and doing the Chunk.setBlocksInArea(): for(int x = 0; x < 8; x++){ for(int y = 0; y < 8; y++){ nx = x+(coordX - camCoordX)*8 ny = y+(coordY - camCoordY)*8 for(int z = 0; z < height[x][y]; z++){ blockarray[x][y][z] = Game.blocksInArea[nx][ny][z]; } } } My reasoning was that this would be much faster than doing the perlin noise all over again, but there are still little spikes of lag when you move in between chunks. Edit: Would it be possible to create a 3 dimensional array list so that shifting of chunks within the array would not be neccessary?

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  • Why is MaybeChannelBound callable?

    - by William Payne
    The Queue class in the python kombu library inherits from MaybeChannelBound, which in turn implements the call method (making it callable). The call() method itself is a thin wrapper around the bind() method. It is not clear why this was done, as calling the bind() method seems (to my simple mind, at least) to be clearer and more descriptive of the intent of the function. Why would somebody use the call() method in a situation like this?

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