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  • Why i can not load a simple pixel shader effect (. fx) file in xna?

    - by Mehdi Bugnard
    I just want to load a simple *.fx file into my project to make a (pixel shader) effect. But whenever I try to compile my project, I get the following error in visual studio Error List: Errors compiling .. ID3DXEffectCompiler: There were no techniques ID3DXEffectCompiler: Compilation failed I already searched on google and found many people with the same problem. And I realized that it was a problem of encoding. With the return lines unrecognized '\ n' . I tried to copy and paste to notepad and save as with ASCII or UTF8 encoding. But the result is always the same. Do you have an idea please ? Thanks a looot :-) Here is my [.fx] file : sampler BaseTexture : register(s0); sampler MaskTexture : register(s1) { addressU = Clamp; addressV = Clamp; }; //All of these variables are pixel values //Feel free to replace with float2 variables float MaskLocationX; float MaskLocationY; float MaskWidth; float MaskHeight; float BaseTextureLocationX; //This is where your texture is to be drawn float BaseTextureLocationY; //texCoord is different, it is the current pixel float BaseTextureWidth; float BaseTextureHeight; float4 main(float2 texCoord : TEXCOORD0) : COLOR0 { //We need to calculate where in terms of percentage to sample from the MaskTexture float maskPixelX = texCoord.x * BaseTextureWidth + BaseTextureLocationX; float maskPixelY = texCoord.y * BaseTextureHeight + BaseTextureLocationY; float2 maskCoord = float2((maskPixelX - MaskLocationX) / MaskWidth, (maskPixelY - MaskLocationY) / MaskHeight); float4 bitMask = tex2D(MaskTexture, maskCoord); float4 tex = tex2D(BaseTexture, texCoord); //It is a good idea to avoid conditional statements in a pixel shader if you can use math instead. return tex * (bitMask.a); //Alternate calculation to invert the mask, you could make this a parameter too if you wanted //return tex * (1.0 - bitMask.a); }

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  • Calculating Screen Resolutions Using WPF

    - by Jeff Ferguson
    WPF measures all elements in device independent pixels (DIPs). These DIPs equate to device pixels if the current display monitor is set to the default of 96 DPI. However, for monitors set to a DPI setting that is different than 96 DPI, then WPF DIPs will not correspond directly to monitor pixels. Consider, for example, the WPF properties SystemParameters.PrimaryScreenHeight and SystemParameters.PrimaryScreenWidth. If your monitor resolution is set to 1024 pixels wide by 768 pixels high, and your monitor is set to 96 DPI, then WPF will report the value of SystemParameters.PrimaryScreenHeight as 768 and the value of SystemParameters.PrimaryScreenWidth as 1024. No problem. This aligns nicely because the WPF device independent pixel value (96) matches your monitor's DPI setting (96). However, if your monitor is not set to display pixels at 96 DPI, then SystemParameters.PrimaryScreenHeight and SystemParameters.PrimaryScreenWidth will not return what you expect. The values returned by these properties may be greater than or less than what you expect, depending on whether or not your monitor's DPI value is less than or greater than 96. Since the SystemParameters.PrimaryScreenHeight and SystemParameters.PrimaryScreenWidth properties are WPF properties, their values are measured in WPF DIPs, rather than taking monitor DPI into effect. Once again: WPF measures all elements in device independent pixels (DIPs). To combat this issue, you must take your monitor's DPI settings into effect if you're looking for the monitor's width and height using the monitor's DPI settings. The handy code block below will help you calculate these values regardless of the DPI setting on your monitor: Window MainWindow = Application.Current.MainWindow; PresentationSource MainWindowPresentationSource = PresentationSource.FromVisual(MainWindow); Matrix m = MainWindowPresentationSource.CompositionTarget.TransformToDevice; DpiWidthFactor = m.M11; DpiHeightFactor = m.M22; double ScreenHeight = SystemParameters.PrimaryScreenHeight * DpiHeightFactor; double ScreenWidth = SystemParameters.PrimaryScreenWidth * DpiWidthFactor; The values of ScreenHeight and ScreenWidth should, after this code is executed, match the resolution that you see in the display's Properties window.

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  • Extreme Optimization – Curves (Function Mapping) Part 1

    - by JoshReuben
    Overview ·        a curve is a functional map relationship between two factors (i.e. a function - However, the word function is a reserved word). ·        You can use the EO API to create common types of functions, find zeroes and calculate derivatives - currently supports constants, lines, quadratic curves, polynomials and Chebyshev approximations. ·        A function basis is a set of functions that can be combined to form a particular class of functions.   The Curve class ·        the abstract base class from which all other curve classes are derived – it provides the following methods: ·        ValueAt(Double) - evaluates the curve at a specific point. ·        SlopeAt(Double) - evaluates the derivative ·        Integral(Double, Double) - evaluates the definite integral over a specified interval. ·        TangentAt(Double) - returns a Line curve that is the tangent to the curve at a specific point. ·        FindRoots() - attempts to find all the roots or zeroes of the curve. ·        A particular type of curve is defined by a Parameters property, of type ParameterCollection   The GeneralCurve class ·        defines a curve whose value and, optionally, derivative and integrals, are calculated using arbitrary methods. A general curve has no parameters. ·        Constructor params:  RealFunction delegates – 1 for the function, and optionally another 2 for the derivative and integral ·        If no derivative  or integral function is supplied, they are calculated via the NumericalDifferentiation  and AdaptiveIntegrator classes in the Extreme.Mathematics.Calculus namespace. // the function is 1/(1+x^2) private double f(double x) {     return 1 / (1 + x*x); }   // Its derivative is -2x/(1+x^2)^2 private double df(double x) {     double y = 1 + x*x;     return -2*x* / (y*y); }   // The integral of f is Arctan(x), which is available from the Math class. var c1 = new GeneralCurve (new RealFunction(f), new RealFunction(df), new RealFunction(System.Math.Atan)); // Find the tangent to this curve at x=1 (the Line class is derived from Curve) Line l1 = c1.TangentAt(1);

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  • Triangulation A* (TA*) pathfinding algorithm

    - by hyn
    I need help understanding the Triangle A* (TA*) algorithm that is described by Demyen in his paper Efficient Triangulation-Based Pathfinding, on pages 76-81. He describes how to adapt the regular A* algorithm for triangulation, to search for other possibly more optimal paths, even after the final node is reached/expanded. Regular A* stops when the final node is expanded, but this is not always the best path when used in a triangulated graph. This is exactly the problem I'm having. The problem is illustrated on page 78, Figure 5.4: I understand how to calculate the g and h values presented in the paper (page 80). And I think the search stop condition is: if (currentNode.fCost > shortestDistanceFound) { // stop break; } where currentNode is the search node popped from the open list (priority queue), which has the lowest f-score. shortestDistanceFound is the actual distance of the shortest path found so far. But how do I exclude the previously found paths from future searches? Because if I do the search again, it will obviously find the same path. Do I reset the closed list? I need to modify something, but I don't know what it is I need to change. The paper lacks pseudocode, so that would be helpful.

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  • Interpolate air drag for my game?

    - by Valentin Krummenacher
    So I have a little game which works with small steps, however those steps vary in time, so for example I sometimes have 10 Steps/second and then I have 20 Steps/second. This changes automatically depending on how many steps the user's computer can take. To avoid inaccurate positioning of the game's player object I use y=v0*dt+g*dt^2/2 to determine my objects y-position, where dt is the time since the last step, v0 is the velocity of my object in the beginning of my step and g is the gravity. To calculate the velocity in the end of a step I use v=v0+g*dt what also gives me correct results, independent of whether I use 2 steps with a dt of for example 20ms or one step with a dt of 40ms. Now I would like to introduce air drag. For simplicity's sake I use a=k*v^2 where a is the air drag's acceleration (I am aware that it would usually result in a force, but since I assume 1kg for my object's mass the force is the same as the resulting acceleration), k is a constant (in this case I'm using 0.001) and v is the speed. Now in an infinitely small time interval a is k multiplied by the velocity in this small time interval powered by 2. The problem is that v in the next time interval would depend on the drag of the last which again depends on the v of the last interval and so on... In other words: If I use a=k*v^2 I get different results for my position/velocity when I use 2 steps of 20ms than when I use one step of 40ms. I used to have this problem for my position too, but adding +g*dt^2/2 to the formula for my position fixed the problem since it takes into account that the position depends on the velocity which changes slightly in every infinitely small time interval. Does something like that exist for air drag too? And no, I dont mean anything like Adding air drag to a golf ball trajectory equation or similar, for that kind of method only gives correct results when all my steps are the same. (I hope you can understand my intermediate english, it's not my main language so I would like to say sorry for all the silly mistakes I might have made in my question)

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  • Drawing particles with CPU instead of GPU (XNA)

    - by Helix
    I'm trying out modifications to the following particle system. http://create.msdn.com/en-US/education/catalog/sample/particle_3d I have a function such that when I press Space, all the particles have their positions and velocities set to 0. for (int i = 0; i < particles.GetLength(0); i++) { particles[i].Position = Vector3.Zero; particles[i].Velocity = Vector3.Zero; } However, when I press space, the particles are still moving. If I go to FireParticleSystem.cs I can turn settings.Gravity to 0 and the particles stop moving, but the particles are still not being shifted to (0,0,0). As I understand it, the problem lies in the fact that the GPU is processing all the particle positions, and it's calculating where the particles should be based on their initial position, their initial velocity and multiplying by their age. Therefore, all I've been able to do is change the initial position and velocity of particles, but I'm unable to do it on the fly since the GPU is handling everything. I want the CPU to calculate the positions of the particles individually. This is because I will be later implementing some sort of wind to push the particles around. How do I stop the GPU from taking over? I think it's something to do with VertexBuffers and the draw function, but I don't know how to modify it to make it work.

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  • Collision detection on a 2D hexagonal grid

    - by SundayMonday
    I'm making a casual grid-based 2D iPhone game using Cocos2D. The grid is a "staggered" hex-like grid consisting of uniformly sized and spaced discs. It looks something like this. I've stored the grid in a 2D array. Also I have a concept of "surrounding" grid cells. Namely the six grid cells surrounding a particular cell (except those on the boundries which can have less than six). Anyways I'm testing some collision detection and it's not working out as well as I had planned. Here's how I currently do collision detection for a moving disc that's approaching the stationary group of discs: Calculate ij-coordinates of grid cell closest to moving cell using moving cell's xy-position Get list of surrounding grid cells using ij-coordinates Examine the surrounding cells. If they're all empty then no collision If we have some non-empty surrounding cells then compare the distance between the disc centers to some minimum distance required for a collision If there's a collision then place the moving disc in grid cell ij So this works but not too well. I've considered a potentially simpler brute force approach where I just compare the moving disc to all stationary discs at each step of the game loop. This is probably feasible in terms of performance since the stationary disc count is 300 max. If not then some space-partitioning data structure could be used however that feels too complex. What are some common approaches and best practices to collision detection in a game like this?

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  • Decal implementation

    - by dreta
    I had issues finding information about decals, so maybe this question will help others. The implementation is for a forward renderer. Could somebody confirm if i got decal implementation right? You define a cube of any dimension that'll define the projection volume in common space. You check for triangle intersection with the defined cube to recieve triangles that the projection will affect. You clip these triangles and save them. You then use matrix tricks to calculate UV coordinates for the saved triangles that'll reference the texture you're projecting. To do this you take the vectors representing height, width and depth of the cube in common space, so that f.e. the bottom left corner is the origin. You put that in a matrix as the i, j, k unit vectors, set the translation for the cube, then you inverse this matrix. You multiply the vertices of the saved triangles by this matrix, that way you get their coordinates inside of a 0 to 1 size cube that you use as the UV coordinates. This way you have the original triangles you're projecting onto and you have UV coordinates for them (the UV coordinates are referencing the texture you're projecting). Then you rerender the saved triangles onto the scene and they overwrite the area of projection with the projected image. Now the questions that i couldn't find answers for. Is the last point right? I've never done software clipping, but it seems error prone enough, due to limited precision, that the'll be some z fighting occuring for the projected texture. Also is the way of getting UV coordinates correct?

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  • How to improve batching performance

    - by user4241
    Hello, I am developing a sprite based 2D game for mobile platform(s) and I'm using OpenGL (well, actually Irrlicht) to render graphics. First I implemented sprite rendering in a simple way: every game object is rendered as a quad with its own GPU draw call, meaning that if I had 200 game objects, I made 200 draw calls per frame. Of course this was a bad choice and my game was completely CPU bound because there is a little CPU overhead assosiacted in every GPU draw call. GPU stayed idle most of the time. Now, I thought I could improve performance by collecting objects into large batches and rendering these batches with only a few draw calls. I implemented batching (so that every game object sharing the same texture is rendered in same batch) and thought that my problems are gone... only to find out that my frame rate was even lower than before. Why? Well, I have 200 (or more) game objects, and they are updated 60 times per second. Every frame I have to recalculate new position (translation and rotation) for vertices in CPU (GPU on mobile platforms does not support instancing so I can't do it there), and doing this calculation 48000 per second (200*60*4 since every sprite has 4 vertices) simply seems to be too slow. What I could do to improve performance? All game objects are moving/rotating (almost) every frame so I really have to recalculate vertex positions. Only optimization that I could think of is a look-up table for rotations so that I wouldn't have to calculate them. Would point sprites help? Any nasty hacks? Anything else? Thanks.

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  • Traffic estimation for a multiplayer flash game

    - by Steve Addington
    hey, i want to know if my rough traffic estimations are right, it would be for a pretty simple realtime flashgame in the style of haxball (but not as a soccer game) heres a video of it http://www.youtube.com/watch?v=z_xBdFg1RcI So here comes my estimation, i dont know if they are realistic! i hope someone can help me. consider the packet attached as a typical one sent every 200ms, its 148bytes + 64 bytes of header will make around a 200bytes packet. The server will receive 200bytes x 6 players x 5 times a sec=6000bytes/s=5.85Kbytes/s=46.9kbit/s plus he has to send all back to the players, so at this point are 94Kbit/s.The server received all the information, perform the definitive calculation and send the new position to all players, in a bigger packet of around 900bytes that have to be delivered to the others 6, which makes 900bytes x 6 players x 5 times a sec=27000bytes/s=26Kbytes/s=210kbit/s. overall that would be 26kbyte per second. thats like 130mb traffic per hour for a 6player room. but somehow i think the numbers are too high? that would be really much traffic for such a simple game. did i calculate something wrong?

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  • Error mounting: mount exited with exit code 13

    - by Mike Williamson
    I keep a windows partition on my laptop for the occaisional bit of Photoshop work. A while ago I noticed that Windows had disappeared from my grub boot menu and when I try to mount the windows partion, my system hangs for a bit and then I get this: Unable to mount 105 GB Filesystem Error mounting: mount exited with exit code 13: ntfs_attr_pread_i: ntfs_pread failed: Input/output error Failed to calculate free MFT records: Input/output error NTFS is either inconsistent, or there is a hardware fault, or it's a SoftRAID/FakeRAID hardware. In the first case run chkdsk /f on Windows then reboot into Windows twice. The usage of the /f parameter is very important! If the device is a SoftRAID/FakeRAID then first activate it and mount a different device under the /dev/mapper/ directory, (e.g. /dev/mapper/nvidia_eahaabcc1). Please see the 'dmraid' documentation for more details. It seems that chkdsk is a windows command but since I can't boot into windows (since its the windows partition that is the problem) I'm not sure what to do. Here is the output of fdisk to give you the lay of the land: Disk /dev/sda: 250.1 GB, 250059350016 bytes 255 heads, 63 sectors/track, 30401 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x98000000 Device Boot Start End Blocks Id System /dev/sda1 1 10199 81923436 83 Linux /dev/sda2 * 10200 22947 102398310 7 HPFS/NTFS /dev/sda3 22948 29164 49938052+ 83 Linux /dev/sda4 29165 30401 9936202+ 5 Extended /dev/sda5 29165 30401 9936171 82 Linux swap / Solaris Any guidance would be appreciated!

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  • Approaches to timed puzzle elements

    - by ndg
    I'm working on a side scrolling game that has a number of timed puzzle elements. As a simple example: I have a number of moving platforms that have been setup to transition in a pattern. Ideally I'd like to ensure that as the player first approaches them, they are in an ideal state -- whereby the player can witness the full transition and more experienced players (i.e: speedrunners) can complete the puzzle immediately without having to wait for the current transition to complete. The issue here, in a nutshell, is that because these platforms begin transitioning at the start of the level, it's impossible to correctly calculate when the player is likely to stumble upon them. I've done a fair bit of Googling but haven't managed to turn up any decent resources with regards to solving a problem like this. The obvious solution is to only begin updating the objects when the player (or more likely: the camera) first encounters them. But this becomes difficult when you consider more complicated situations. It seems like potentially the easiest way of handling this is to have an invisible trigger volume that will tell any puzzle elements located inside of it that the player has 'arrived' upon first colliding with the player. But this would mean I'd have to logically group puzzle elements, which could become fairly messy in a hurry. Take, for instance, a puzzle that appears to the right of the screen. It may take the player a number of seconds to reach it. It would look strange if the elements involved were to remain stationary. But by the time the player arrives, it's likely things will be 'out of sync'. I wanted to post here in the hopes that others know of, or have implemented, a decent solution to this problem?

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  • box2d tween what am I missing

    - by philipp
    I have a Box2D project and I want to tween an kinematic body from position A, to position B. The tween function, got it from this blog: function easeInOut(t , b, c, d ){ if ( ( t /= d / 2 ) < 1){ return c/2 * t * t * t * t + b; } return -c/2 * ( (t -= 2 ) * t * t * t - 2 ) + b; } where t is the current value, b the start, c the end and d the total amount of frames (in my case). I am using the method introduced by this lesson of todd's b2d tutorials to move the body by setting its linear Velocity so here is relevant update code of the sprite: if( moveData.current == moveData.total ){ this._body.SetLinearVelocity( new b2Vec2() ); return; } var t = easeNone( moveData.current, 0, 1, moveData.total ); var step = moveData.length / moveData.total * t; var dir = moveData.direction.Copy(); //this is the line that I think might be corrected dir.Multiply( t * moveData.length * fps /moveData.total ) ; var bodyPosition = this._body.GetWorldCenter(); var idealPosition = bodyPosition.Copy(); idealPosition.Add( dir ); idealPosition.Subtract( bodyPosition.Copy() ); moveData.current++; this._body.SetLinearVelocity( idealPosition ); moveData is an Object that holds the global values of the tween, namely: current frame (int), total frames (int), the length of the total distance to travel (float) the direction vector (targetposition - bodyposition) (b2Vec2) and the start of the tween (bodyposition) (b2Vec2) Goal is to tween the body based on a fixed amount of frames: in moveData.total frames. The value of t is always between 0 and 1 and the only thing that is not working correctly is the resulting distance the body travels. I need to calculate the multiplier for the direction vector. What am I missing to make it work?? Greetings philipp

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  • Optimizing hash lookup & memory performance in Go

    - by Moishe
    As an exercise, I'm implementing HashLife in Go. In brief, HashLife works by memoizing nodes in a quadtree so that once a given node's value in the future has been calculated, it can just be looked up instead of being re-calculated. So eg. if you have a node at the 8x8 level, you remember it by its four children (each at the 2x2 level). So next time you see an 8x8 node, when you calculate the next generation, you first check if you've already seen a node with those same four children. This is extended up through all levels of the quadtree, which gives you some pretty amazing optimizations if eg. you're 10 levels above the leaves. Unsurprisingly, it looks like the perfmance crux of this is the lookup of nodes by child-node values. Currently I have a hashmap of {&upper_left_node,&upper_right_node,&lower_left_node,&lower_right_node} -> node So my lookup function is this: func FindNode(ul, ur, ll, lr *Node) *Node { var node *Node var ok bool nc := NodeChildren{ul, ur, ll, lr} node, ok = NodeMap[nc] if ok { return node } node = &Node{ul, ur, ll, lr, 0, ul.Level + 1, nil} NodeMap[nc] = node return node } What I'm trying to figure out is if the "nc := NodeChildren..." line causes a memory allocation each time the function is called. If it does, can I/should I move the declaration to the global scope and just modify the values each time this function is called? Or is there a more efficient way to do this? Any advice/feedback would be welcome. (even coding style nits; this is literally the first thing I've written in Go so I'd love any feedback)

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  • How to implement a birds eye view of 2D Grid Map using Android

    - by IM_Adan
    I'm a true beginner with using the android platform and I'm having difficulties on implementing a 2D grid system for a tower defense type game. Where I can place towers on a specific tile and enemies will be able to traverse through tiles etc. What I would like is a practical explanation of how I could tackle this. A step by step guide for dummies. This is what I believe are the necessary steps to take, I think I might be wrong but I hope someone could help me out. Calculate the Width and Height of the view I'm working with. Based on that, determine the number of tiles required and their dimensions, (Still not sure how I would do this) Create each tile as a Rectangle object and draw these rectangle on a canvas I would really be grateful if someone could steer me in the right direction on how to implement a 2D Grid Map using android. I hope the answer to this questions helps the TRUE beginners out there like me. I have looked at the following links below yet I still feel that I don't trully understand what's going on. For XNA: 2D Grid based game - how should I draw grid lines? How to Create a Grid for a 2D Game? Also a quick note: All my previous game development has been in Java, mostly using Java SE and Swing. I also have good understanding of the game development process, it is only android thats confusing me :S

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  • Is it better to hard code data or find an algorithm?

    - by OghmaOsiris
    I've been working on a boardgame that has a hex grid as the board (the upper right grid in the image below) Since the board will never change and the spaces on the board will always be linked to the same other spaces around it, should I just hard code every space with the values that I need? Or should I use various algorithms to calculate links and traversals? To be more specific, my board game is a 4 player game where each player has a 5x5x5x5x5x5 hex grid (again, the upper right grid in th eimage above). The object is to get from the bottom of the grid to the top, with various obstacles in the way, and each players being able to attack eachother from the edge of their grid onto other players based on a range multiplier. Since the players grid will never change and the distance of any arbitrary space from the edge of the grid will always be the same, should I just hard code this number into each of the spaces, or should I still use a breadth first search algorithm when players are attacking? The only con I can think of for hard coding everything is that I'm going to code 9+ 2(5+6+7+8) = 61 individual cells. Is there anything else that I'm missing that I should consider using more complex algorithms?

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  • I can't upgrade to 12.10 Quantal Quetzal

    - by JamesTheAwesomeDude
    After hearing about some of the features in 12.10, I decided to upgrade my Ubuntu from 12.04 LTS to the newer 12.10. However, when I try to upgrade it, I start the update manager, like always, and I start the distro upgrade, just like I do every time there's a new version, but at the end of the "Setting new software channels" stage, it fails, saying: Could not calculate the upgrade An unresolvable problem occurred while calculating the upgrade: E: Unable to correct problems, you have held broken packages. This can be caused by: Upgrading to a pre-release version of Ubuntu Running the current pre-release version of Ubuntu Unofficial software packages not provided by Ubuntu If none of this applies, then please report this bug using the command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal. What should I do? I understand that I have some sort of "broken" package on my system, but how do I identify and remove the problem? Note: At the start of the "Setting new software channels" stage, I was presented with this: Third party sources disabled Some third party entries in your sources.list were disabled. You can re-enable them after the upgrade with the 'software-properties' tool or your package manager.

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  • Suitability of ground fog using layered alpha quads?

    - by Nick Wiggill
    A layered approach would use a series of massive alpha-textured quads arranged parallel to the ground, intersecting all intervening terrain geometry, to provide the illusion of ground fog quite effectively from high up, looking down, and somewhat less effectively when inside the fog and looking toward the horizon (see image below). Alternatively, a shader-heavy approach would instead calculate density as function of view distance into the ground fog substrate, and output the fragment value based on that. Without having to performance-test each approach myself, I would like first to hear others' experiences (not speculation!) on what sort of performance impact the layered alpha texture approach is likely to have. I ask specifically due to the oft-cited impacts of overdraw (not sure how fill-rate bound your average desktop system is). A list of games using this approach, particularly older games, would be immensely useful: if this was viable on pre DX9/OpenGL2 hardware, it is likely to work fine for me. One big question is in regards to this sort of effect: (Image credit goes to Lume of lume.com) Notice how the vertical fog gradation is continuous / smooth. OTOH, using textured quad layers, I can only assume that layers would be mighty obvious when walking through them -- the more sparse they were, the more obvious this would be. This is in contrast to where fog planes are aligned to face the player every frame, where this coarseness would be much less obvious.

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  • Extreme Optimization –Mathematical Constants and Basic Functions

    - by JoshReuben
    Machine constants The MachineConstants class - contains constants for floating-point arithmetic because the CLS System.Single and Double floating-point types do not follow the standard conventions and are useless. machine constants for the Double type: machine precision: Epsilon , SqrtEpsilon CubeRootEpsilon largest possible value: MaxDouble , SqrtMaxDouble, LogMaxDouble smallest Double-precision floating point number that is greater than zero: MinDouble , SqrtMinDouble , LogMinDouble A similar set of constants is available for the Single Datatype  Mathematical Constants The Constants class contains static fields for many mathematical constants and common expressions involving small integers – if you are doing thousands of iterations, you wouldn't want to calculate OneOverSqrtTwoPi , Sqrt17 or Log17 !!! Fundamental constants E - The base for the natural logarithm, e (2.718...). EulersConstant - (0.577...). GoldenRatio - (1.618...). Pi - the ratio between the circumference and the diameter of a circle (3.1415...). Expressions involving fundamental constants: TwoPi, PiOverTwo, PiOverFour, LogTwoPi, PiSquared, SqrPi, SqrtTwoPi, OneOverSqrtPi, OneOverSqrtTwoPi Square roots of small integers: Sqrt2, Sqrt3, Sqrt5, Sqrt7, Sqrt17 Logarithms of small integers: Log2, Log3, Log10, Log17, InvLog10  Elementary Functions The IterativeAlgorithm<T> class in the Extreme.Mathematics namespace defines many elementary functions that are missing from System.Math. Hyperbolic Trig Functions: Cosh, Coth, Csch, Sinh, Sech, Tanh Inverse Hyperbolic Trig Functions: Acosh, Acoth, Acsch, Asinh, Asech, Atanh Exponential, Logarithmic and Miscellaneous Functions: ExpMinus1 - The exponential function minus one, ex-1. Hypot - The hypotenuse of a right-angled triangle with specified sides. LambertW - Lambert's W function, the (real) solution W of x=WeW. Log1PlusX - The natural logarithm of 1+x. Pow - A number raised to an integer power.

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  • Flip rotation matrix

    - by azer89
    right now i'm doing character control with kinect. Basically i need to mirror the joint orientation because the character faces the player. Somehow by googling through internet i've done it and everything works very well. But i have little idea about how the math works, here's my code: //------------------------------------------------------------------------------------- Ogre::Quaternion JointOrientationCalculator::buildQuaternion(Ogre::Vector3 xAxis, Ogre::Vector3 yAxis, Ogre::Vector3 zAxis) { Ogre::Matrix3 mat; if(isMirror) { mat = Ogre::Matrix3(xAxis.x, yAxis.x, zAxis.x, xAxis.y, yAxis.y, zAxis.y, xAxis.z, yAxis.z, zAxis.z); Ogre::Matrix3 flipMat(1, 0, 0, 0, 1, 0, 0, 0, -1); mat = flipMat * mat * flipMat; } else { mat = Ogre::Matrix3(xAxis.x, -yAxis.x, zAxis.x, -xAxis.y, yAxis.y, -zAxis.y, xAxis.z, -yAxis.z, zAxis.z); } Ogre::Quaternion q; q.FromRotationMatrix(mat); return q; } when i need to mirror/flip it by axes z i calculate mat = flipMat * mat * flipMat; but i don't understand how this equation works.

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  • Demystifying "chunked level of detail"

    - by Caius Eugene
    Just recently trying to make sense of implementing a chunked level of detail system in Unity. I'm going to be generating four mesh planes, each with a height map but I guess that isn't too important at the moment. I have a lot of questions after reading up about this technique, I hope this isn't too much to ask all in one go, but I would be extremely grateful for someone to help me make sense of this technique. 1 : I can't understand at which point down the Chunked LOD pipeline that the mesh gets split into chunks. Is this during the initial mesh generation, or is there a separate algorithm which does this. 2 : I understand that a Quadtree data structure is used to store the Chunked LOD data, I think i'm missing the point a bit, but Is the quadtree storing vertex and triangles data for each subdivision level? 3a : How is the camera distance usually calculated. When reading up about quadtree's, Axis-aligned bounding box's are mentioned a lot. In this case would each chunk have a collision bounding box to detect the camera or player is nearby? or is there a better way of doing this? (raycast maybe?) 3b : Do the chunks calculate the camera distance themselves? 4 : Does each chunk have the same "resolution". for example at top level the mesh will be 32x32, will each subdivided node also be 32x32. Example below:

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  • Basket Analysis with #dax in #powerpivot and #ssas #tabular

    - by Marco Russo (SQLBI)
    A few days ago I published a new article on DAX Patterns web site describing how to implement Basket Analysis in DAX. This topic is a very classical one and is also covered in the many-to-many revolution white paper. It has been also discussed in several blog posts, listed here in historical order: Simple Basket Analysis in DAX by Chris Webb PowerPivot, basket analysis and the hidden many to many by Alberto Ferrari Applied Basket Analysis in Power Pivot using DAX by Gerhard Brueckl As usual, in DAX Patterns we try to present the required DAX formulas in a way that is easy to adapt to specific models. We also try to show a good implementation from a performance point of view. Further optimizations are always possible in DAX. However, in order to keep the model simple to adapt in different scenarios, we avoid presenting optimizations that would require particular assumptions or restrictions on the data model. I hope you will find the Basket Analysis pattern useful. Even if you do not need it today, reading the DAX formula is a good exercise to check your knowledge of evaluation contexts in DAX. For example, describing how does it work the following expression is not a trivial task! [Orders with Both Products] := CALCULATE (     DISTINCTCOUNT ( Sales[SalesOrderNumber] ),     CALCULATETABLE (         SUMMARIZE ( Sales, Sales[SalesOrderNumber] ),         ALL ( Product ),         USERELATIONSHIP ( Sales[ProductCode], 'Filter Product'[Filter ProductCode] )     ) ) The good news is that you can use the patterns even if you do not really understand all the details of the DAX formulas you are using! Any feedback on this new pattern is very welcome.

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  • Effective way to check if an Entity/Player enters a region/trigger

    - by Chris
    I was wondering how multiplayer games detect if you enter a special region. Let's assume there is a huge map that is so big that simply checking it would become a huge performance issue. I've seen bukkit (a modding API for Minecraft servers) firing an Event on every single move. I don't think that larger games do the same because even if you have only a few coordinates you are interested in, you have to loop through a few trigger zone to see if the player is inside your region - for every player. This seems like an extremely CPU-intense operation to me even though I've never developed something like that. Is there a special algorithm that is used by larger games to accomplish this? The only thing I could imagine is to split up the world into multiple parts and to register the event not on the movement itself but on all the parts that are covered by your area and only check for areas that are registered in the current part. And another thing I would like to know: How could you detect when someone must have entered a trigger but you never saw him directly in it since his client only sent you an move packet shortly before entering and after leaving the trigger area. Drawing a line and calculate all colliding parts seems rather CPU intensive if you have to perform it every time.

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  • How can I generate a view or projection matrix for OpenGL 3.+

    - by Ken
    I'm transitioning from OpenGL 2 to OpenGL 3.+ and to GLSL 1.5. I'm trying to avoid using the deprecated features. My question how do we now generate the view or projection matrix. I was using the matrix stack to calculate the projection matrix for me; GLfloat ptr[16]; gluPerspective(...); glGetFloatv(GL_MODELVIEW_MATRIX, ptr); //then pass ptr via a uniform to the shader But obviously the matrix stack is deprecated. So this approach is not the best an option going forward. I have the 'Red Book', 7th ed, which covers 3.0 & 3.1 and it still uses the deprecated matrix functions in it's examples. I could write some utility-code myself to generate the matrices. But I don't want to re-invent this particular wheel, especially when this functionality is required for every 3D graphics program. What is the accepted way to generate world,view & projection matrices for OpenGL? Is there an emerging 'standard' library for this? Or is there some other hidden (to me) functionality in OpenGL/GLSL which I have overlooked?

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  • Cropping a line (laser beam) in XNA

    - by electroflame
    I have a laser sprite that I wish to crop. I want to crop it so when it collides with an item, I can calculate the distance between the starting point, and the ending point, and only draw that. This eliminates the "overdraw" of a laser drawing past an item. Essentially, I'm trying to crop a line, but also keep that line "attached" to the nose of my ship. The line should not be drawn past the nose of my ship, that should be the starting point. There is no rotation to worry about. Currently, I thought that doing this through SpriteBatch would be best. This is my current Spritebatch code: spriteBatch.Draw(Laser.sprite, new Rectangle((int)Laser.position.X, (int)Laser.position.Y, Laser.sprite.Width, LaserHeight), new Rectangle(0, 0, (int)(Laser.sprite.Width), LaserHeight), new Color(255, 255, 255, (byte)MathHelper.Clamp(Laser.Alpha, 0, 255)), Laser.rotation, new Vector2(Laser.sprite.Width/2, LaserHeight/2), SpriteEffects.None, 0); But this doesn't quite work. It does only draw part of the sprite, but when LaserHeight is incremented, it lengthens the line in both ways! I believe this is due to some stupid error on my part with the Origin of the draw. Quick recap: I need to have my laser sprite drawn with the bottom of it at the nose of my ship, and then use LaserHeight to crop the image so only part of it is drawn. I have a feeling my explanation is a bit...lacking. So if you require more information, please say so and I will try to provide more information. Thanks in advance!

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