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  • Unreal 3 Editor (Unreal Tournament 3) Why does the X Y Z translations now rotate along with my static meshes?

    - by Gareth Jones
    So I was making a map for UT3, using the Unreal 3 Editor provided, and all was going well. However I was doing some work with InterpActors and Vehicle Spawners, when I must have hit a key by mistake (or other wise somehow changed something) by mistake. Now the X Y Z translations that are used to move objects around in the editor will rotate along with the object (Ive put images down below to help show what I mean) - This is very annoying because it also changes the direction the arrow keys move a rotated object, in the example below, the Down arrow key will now move the object to the right. How can I fix this? (Note both images are taken from the same viewpoint) Before Rotation: After Rotation: P.S. If someone could please provide me with the correct / better name for the X Y Z "things" it would be much appreciated, thanks!

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  • How to create an extensible rope in Box2D?

    - by Thomas
    Let's say I'm trying to create a ninja lowering himself down a rope, or pulling himself back up, all whilst he might be swinging from side to side or hit by objects. Basically like http://ninja.frozenfractal.com/ but with Box2D instead of hacky JavaScript. Ideally I would like to use a rope joint in Box2D that allows me to change the length after construction. The standard Box2D RopeJoint doesn't offer that functionality. I've considered a PulleyJoint, connecting the other end of the "pulley" to an invisible kinematic body that I can control to change the length, but PulleyJoint is more like a rod than a rope: it constrains maximum length, but unlike RopeJoint it constrains the minimum as well. Re-creating a RopeJoint every frame using a new length is rather inefficient, and I'm not even sure it would work properly in the simulation. I could create a "chain" of bodies connected by RotationJoints but that is also less efficient, and less robust. I also wouldn't be able to change the length arbitrarily, but only by adding and removing a whole number of links, and it's not obvious how I would connect the remainder without violating existing joints. This sounds like something that should be straightforward to do. Am I overlooking something?

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  • Mandelbrot set not displaying properly

    - by brainydexter
    I am trying to render mandelbrot set using glsl. I'm not sure why its not rendering the correct shape. Does the mandelbrot calculation require values to be within a range for the (x,y) [ or (real, imag) ] ? Here is a screenshot: I render a quad as follows: float w2 = 6; float h2 = 5; glBegin(GL_QUADS); glVertex3f(-w2, h2, 0.0); glVertex3f(-w2, -h2, 0.0); glVertex3f(w2, -h2, 0.0); glVertex3f(w2, h2, 0.0); glEnd(); My vertex shader: varying vec3 Position; void main(void) { Position = gl_Vertex.xyz; gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; } My fragment shader (where all the meat is): uniform float MAXITERATIONS; varying vec3 Position; void main (void) { float zoom = 1.0; float centerX = 0.0; float centerY = 0.0; float real = Position.x * zoom + centerX; float imag = Position.y * zoom + centerY; float r2 = 0.0; float iter; for(iter = 0.0; iter < MAXITERATIONS && r2 < 4.0; ++iter) { float tempreal = real; real = (tempreal * tempreal) + (imag * imag); imag = 2.0 * real * imag; r2 = (real * real) + (imag * imag); } vec3 color; if(r2 < 4.0) color = vec3(1.0); else color = vec3( iter / MAXITERATIONS ); gl_FragColor = vec4(color, 1.0); }

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  • How to have operations with character/items in binary with concrete operations?

    - by Piperoman
    I have the next problem. A item can have a lot of states: NORMAL = 0000000 DRY = 0000001 HOT = 0000010 BURNING = 0000100 WET = 0001000 COLD = 0010000 FROZEN = 0100000 POISONED= 1000000 A item can have some states at same time but not all of them Is impossible to be dry and wet at same time. If you COLD a WET item, it turns into FROZEN. If you HOT a WET item, it turns into NORMAL A item can be BURNING and POISON Etc. I have tried to set binary flags to states, and use AND to combine different states, checking before if it is possible or not to do it, or change to another status. Does there exist a concrete approach to solve this problem efficiently without having an interminable switch that checks every state with every new state? It is relatively easy to check 2 different states, but if there exists a third state it is not trivial to do.

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  • OpenGL ES Loading

    - by kuroutadori
    I want to know what is the norm of loading rendering code. Take a button. When the application is loaded, a texture is loaded which has the image of the button on it. When the button is tapped, it then adds a loader into a queue, which is loaded on render thread. It then loads up an array buffer with vertexes and tex coords when render is called. It then adds to a render tree. Then it renders. the render function looks like this void render() { update(); mBaseRenderer->render(); } update() is when the queue is checked to see if anything needs loading. mBaseRenderer->render() is the render tree. What I am asking then is, should I even have the update() there at all and instead have everything preloaded before it renders? If I can have it loaded when need, for instance when there is tap, then how can it be done (My current code causes an dequeueing buffer error (Unknown error: -75) which I assume is to do with OpenGL ES and the context)?

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  • vector rotations for branches of a 3d tree

    - by freefallr
    I'm attempting to create a 3d tree procedurally. I'm hoping that someone can check my vector rotation maths, as I'm a bit confused. I'm using an l-system (a recursive algorithm for generating branches). The trunk of the tree is the root node. It's orientation is aligned to the y axis. In the next iteration of the tree (e.g. the first branches), I might create a branch that is oriented say by +10 degrees in the X axis and a similar amount in the Z axis, relative to the trunk. I know that I should keep a rotation matrix at each branch, so that it can be applied to child branches, along with any modifications to the child branch. My questions then: for the trunk, the rotation matrix - is that just the identity matrix * initial orientation vector ? for the first branch (and subsequent branches) - I'll "inherit" the rotation matrix of the parent branch, and apply x and z rotations to that also. e.g. using glm::normalize; using glm::rotateX; using glm::vec4; using glm::mat4; using glm::rotate; vec4 vYAxis = vec4(0.0f, 1.0f, 0.0f, 0.0f); vec4 vInitial = normalize( rotateX( vYAxis, 10.0f ) ); mat4 mRotation = mat4(1.0); // trunk rotation matrix = identity * initial orientation vector mRotation *= vInitial; // first branch = parent rotation matrix * this branches rotations mRotation *= rotate( 10.0f, 1.0f, 0.0f, 0.0f ); // x rotation mRotation *= rotate( 10.0f, 0.0f, 0.0f, 1.0f ); // z rotation Are my maths and approach correct, or am I completely wrong? Finally, I'm using the glm library with OpenGL / C++ for this. Is the order of x rotation and z rotation important?

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  • Can't get sprite to rotate correctly?

    - by rphello101
    I'm attempting to play with graphics using Java/Slick 2d. I'm trying to get my sprite to rotate to wherever the mouse is on the screen and then move accordingly. I figured the best way to do this was to keep track of the angle the sprite is at since I have to multiply the cosine/sine of the angle by the move speed in order to get the sprite to go "forwards" even if it is, say, facing 45 degrees in quadrant 3. However, before I even worry about that, I'm having trouble even getting my sprite to rotate in the first place. Preliminary console tests showed that this code worked, but when applied to the sprite, it just kind twitches. Anyone know what's wrong? int mX = Mouse.getX(); int mY = HEIGHT - Mouse.getY(); int pX = sprite.x; int pY = sprite.y; int tempY, tempX; double mAng, pAng = sprite.angle; double angRotate=0; if(mX!=pX){ tempY=pY-mY; tempX=mX-pX; mAng = Math.toDegrees(Math.atan2(Math.abs((tempY)),Math.abs((tempX)))); if(mAng==0 && mX<=pX) mAng=180; } else{ if(mY>pY) mAng=270; else mAng=90; } //Calculations if(mX<pX&&mY<pY){ //If in Q2 mAng = 180-mAng; } if(mX<pX&&mY>pY){ //If in Q3 mAng = 180+mAng; } if(mX>pX&&mY>pY){ //If in Q4 mAng = 360-mAng; } angRotate = mAng-pAng; sprite.angle = mAng; sprite.image.setRotation((float)angRotate);

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  • Object detection in bitmap JavaScript canvas

    - by fallenAngel
    I want to detect clicks on canvas elements which are drawn using paths. So far I have stored element paths in a JavaScript data structure and then check the coordinates of hits which match the element's coordinates. Rendering each element path and checking the hits would be inefficient when there are a lot of elements. I believe there must be an algorithm for this kind of coordinate search, can anyone help me with this?

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  • Render full-screen gradient or texture

    - by Filip Skakun
    What's the simplest way to fill the background of the screen with a gradient or a texture in Direct3D 10/11? I'm building a Windows 8 metro app in which the camera never moves and I render some content in D3D, but I need to fill the background with something else than a solid color. Do I need to figure out the size and position of a rectangle and position it in 3D space or can I have some simpler solution? I don't care about depth at all, I don't use any depth buffer since all my content is sorted back to front, so I could just start by drawing to the background.

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  • Black Screen: How to set Projection/View Matrix

    - by Lisa
    I have a Windows Phone 8 C#/XAML with DirectX component project. I'm rendering some particles, but each particle is a rectangle versus a square (as I've set the vertices to be positions equally offset from each other). I used an Identity matrix in the view and projection matrix. I decided to add the windows aspect ratio to prevent the rectangles. But now I get a black screen. None of the particles are rendered now. I don't know what's wrong with my matrices. Can anyone see the problem? These are the default matrices in Microsoft's project example. View Matrix: XMVECTOR eye = XMVectorSet(0.0f, 0.7f, 1.5f, 0.0f); XMVECTOR at = XMVectorSet(0.0f, -0.1f, 0.0f, 0.0f); XMVECTOR up = XMVectorSet(0.0f, 1.0f, 0.0f, 0.0f); XMStoreFloat4x4(&m_constantBufferData.view, XMMatrixTranspose(XMMatrixLookAtRH(eye, at, up))); Projection Matrix: void CubeRenderer::CreateWindowSizeDependentResources() { Direct3DBase::CreateWindowSizeDependentResources(); float aspectRatio = m_windowBounds.Width / m_windowBounds.Height; float fovAngleY = 70.0f * XM_PI / 180.0f; if (aspectRatio < 1.0f) { fovAngleY /= aspectRatio; } XMStoreFloat4x4(&m_constantBufferData.projection, XMMatrixTranspose(XMMatrixPerspectiveFovRH(fovAngleY, aspectRatio, 0.01f, 100.0f))); } I've tried modifying them to use cocos2dx's WP8 example. XMMATRIX identityMatrix = XMMatrixIdentity(); float fovy = 60.0f; float aspect = m_windowBounds.Width / m_windowBounds.Height; float zNear = 0.1f; float zFar = 100.0f; float xmin, xmax, ymin, ymax; ymax = zNear * tanf(fovy * XM_PI / 360); ymin = -ymax; xmin = ymin * aspect; xmax = ymax * aspect; XMMATRIX tmpMatrix = XMMatrixPerspectiveOffCenterRH(xmin, xmax, ymin, ymax, zNear, zFar); XMMATRIX projectionMatrix = XMMatrixMultiply(tmpMatrix, identityMatrix); // View Matrix float fEyeX = m_windowBounds.Width * 0.5f; float fEyeY = m_windowBounds.Height * 0.5f; float fEyeZ = m_windowBounds.Height / 1.1566f; float fLookAtX = m_windowBounds.Width * 0.5f; float fLookAtY = m_windowBounds.Height * 0.5f; float fLookAtZ = 0.0f; float fUpX = 0.0f; float fUpY = 1.0f; float fUpZ = 0.0f; XMMATRIX tmpMatrix2 = XMMatrixLookAtRH(XMVectorSet(fEyeX,fEyeY,fEyeZ,0.f), XMVectorSet(fLookAtX,fLookAtY,fLookAtZ,0.f), XMVectorSet(fUpX,fUpY,fUpZ,0.f)); XMMATRIX viewMatrix = XMMatrixMultiply(tmpMatrix2, identityMatrix); XMStoreFloat4x4(&m_constantBufferData.view, viewMatrix); Vertex Shader cbuffer ModelViewProjectionConstantBuffer : register(b0) { //matrix model; matrix view; matrix projection; }; struct VertexInputType { float4 position : POSITION; float2 tex : TEXCOORD0; float4 color : COLOR; }; struct PixelInputType { float4 position : SV_POSITION; float2 tex : TEXCOORD0; float4 color : COLOR; }; PixelInputType main(VertexInputType input) { PixelInputType output; // Change the position vector to be 4 units for proper matrix calculations. input.position.w = 1.0f; //===================================== // TODO: ADDED for testing input.position.z = 0.0f; //===================================== // Calculate the position of the vertex against the world, view, and projection matrices. //output.position = mul(input.position, model); output.position = mul(input.position, view); output.position = mul(output.position, projection); // Store the texture coordinates for the pixel shader. output.tex = input.tex; // Store the particle color for the pixel shader. output.color = input.color; return output; } Before I render the shader, I set the view/projection matrices into the constant buffer void ParticleRenderer::SetShaderParameters() { ViewProjectionConstantBuffer* dataPtr; D3D11_MAPPED_SUBRESOURCE mappedResource; DX::ThrowIfFailed(m_d3dContext->Map(m_constantBuffer.Get(), 0, D3D11_MAP_WRITE_DISCARD, 0, &mappedResource)); dataPtr = (ViewProjectionConstantBuffer*)mappedResource.pData; dataPtr->view = m_constantBufferData.view; dataPtr->projection = m_constantBufferData.projection; m_d3dContext->Unmap(m_constantBuffer.Get(), 0); // Now set the constant buffer in the vertex shader with the updated values. m_d3dContext->VSSetConstantBuffers(0, 1, m_constantBuffer.GetAddressOf() ); // Set shader texture resource in the pixel shader. m_d3dContext->PSSetShaderResources(0, 1, &m_textureView); } Nothing, black screen... I tried so many different look at, eye, and up vectors. I tried transposing the matrices. I've set the particle center position to always be (0, 0, 0), I tried different positions too, just to make sure they're not being rendered offscreen.

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  • WIn API Basic Paint program

    - by Tom Burman
    Just trying to learn a bit of Win API. Im trying to make a basic drawing app, a bit like MS Paint. For the time being im trying to get one function to work which is, when you left click and drag the mouse around the screen a line is drawn behind the mouse. Heres what i have so far, but for some reason: 1) the line starts drawing straight away rather then waiting for the left click 2) the line isn't solid its very dotty. case WM_MOUSEMOVE: { if(MK_LBUTTON){ hdc = GetDC(hwnd); hPen = CreatePen(PS_SOLID,5,RGB(0, 0, 255)); SelectObject(hdc, hPen); int x = LOWORD(lParam); int y = HIWORD(lParam); MoveToEx(hdc,x,y,NULL); LineTo(hdc, LOWORD(lParam), HIWORD(lParam)); ReleaseDC(hwnd,hdc); } else break; } } Thanks for any help!

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  • Impact of variable-length loops on GPU shaders

    - by Will
    Its popular to render procedural content inside the GPU e.g. in the demoscene (drawing a single quad to fill the screen and letting the GPU compute the pixels). Ray marching is popular: This means the GPU is executing some unknown number of loop iterations per pixel (although you can have an upper bound like maxIterations). How does having a variable-length loop affect shader performance? Imagine the simple ray-marching psuedocode: t = 0.f; while(t < maxDist) { p = rayStart + rayDir * t; d = DistanceFunc(p); t += d; if(d < epsilon) { ... emit p return; } } How are the various mainstream GPU families (Nvidia, ATI, PowerVR, Mali, Intel, etc) affected? Vertex shaders, but particularly fragment shaders? How can it be optimised?

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  • Collision detection code style

    - by Marian Ivanov
    Not only there are two useful broad-phase algorithms and a lot of useful narrowphase algorithms, there are also multiple code styles. Arrays vs. calling Make an array of broadphase checks, then filter them with narrowphase checks, then resolve them. function resolveCollisions(thingyStructure * a,thingyStructure * b,int index){ possibleCollisions = getPossibleCollisions(b,a->get(index)); for(i=0; i<possibleCollitionsNumber; i++){ if(narrowphase(possibleCollisions[i],a[index])) { collisions->push(possibleCollisions[i]); }; }; for(i=0; i<collitionsNumber; i++){ //CODE FOR RESOLUTION }; }; Make the broadphase call the narrowphase, and the narrowphase call the resolution function resolveCollisions(thingyStructure * a,thingyStructure * b,int index){ broadphase(b,a->get(index)); }; function broadphase(thingy * with, thingy * what){ while(blah){ //blahcode narrowphase(what,collidingThing); }; }; Events vs. in-the-loop Fire an event. This abstracts the check away, but it's trickier to make an equal interaction. a[index] -> collisionEvent(eventdata); //much later int collisionEvent(eventdata){ //resolution gets here } Resolve the collision inside the loop. This glues narrowphase and resolution into one layer. if(narrowphase(possibleCollisions[i],a[index])) { //CODE GOES HERE }; The questions are: Which of the first two is better, and how am I supposed to make a zero-sum Newtonian interaction under B1.

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  • glColor3f Setting colour

    - by Aaron
    This draws a white vertical line from 640 to 768 at x512: glDisable(GL_TEXTURE_2D); glBegin(GL_LINES); glColor3f((double)R/255,(double)G/255,(double)B/255); glVertex3f(SX, -SPosY, 0); // origin of the line glVertex3f(SX, -EPosY, 0); // ending point of the line glEnd(); glEnable(GL_TEXTURE_2D); This works, but after having a problem where it wouldn't draw it white (Or to any colour passed) I discovered that disabling GL_TEXTURE_2D Before drawing the line, and the re-enabling it afterwards for other things, fixed it. I want to know, is this a normal step a programmer might take? Or is it highly inefficient? I don't want to be causing any slow downs due to a mistake =) Thanks

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  • How can I transform a Point2f with a matrix on Android?

    - by Vivendi
    I'm developing for Android and I'm using the android.renderscript.Matrix3f class to do some calculations. What I need to do now is to now is to do something like mat.tranform(pointIn, pointOut); So I need to transform a matrix by a given Point class. In awt I would simply do this: AffineTransform t = new AffineTransform(); Point2D.Float p = new Point2D.Float(); t.transform( p, p ); But in Android I now have this: Matrix3f t = new Matrix3f(); PointF p = new PointF(); // Now I need to tranform it somehow.. But the Matrix3f class in Android doesn't have a Matrix.transform(Point2D ptSrc, Point2D ptDst) method. So I guess I have to do the transformation manually. But I'm not really sure how that works. From what I've seen it's something like a translate and then a rotate? Could anyone please tell me how to do this in code?

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  • Workaround the flip queue (AKA pre-rendered frames) in OpenGL?

    - by user41500
    It appears that some drivers implement a "flip queue" such that, even with vsync enabled, the first few calls to swap buffers return immediately (queuing those frames for later use). It is only after this queue is filled that buffer swaps will block to synchronize with vblank. This behavior is detrimental to my application. It creates latency. Does anyone know of a way to disable it or a workaround for dealing with it? The OpenGL Wiki on Swap Interval suggests a call to glFinish after the swap but I've had no such luck with that trick.

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  • Implmenting RLE into a tilemap or how to create a large 3D array?

    - by Smallbro
    Currently I've been using a 3D array for my tiles in a 2D world but the 3D side comes in when moving down into caves and whatnot. Now this is not memory efficient and I switched over to a 2D array and can now have much larger maps. The only issue I'm having now is that it seems that my tiles cannot occupy the same space as a tile on the same z level. My current structure means that each block has its own z variable. This is what it used to look like: map.blockData[x][y][z] = new Block(); however now it works like this map.blockData[x][y] = new Block(z); I'm not sure why but if I decide to use the same space on say the floor below it wont allow me to. Does anyone have any ideas on how I can add a z-axis to my 2D array? I'm using java but I reckon the concept carries across different languages. Edit: As Will posted, RLE sounds like the best method for achieving a fast 3D array. However I'm struggling to understand how I would even start to implement it? Would I create a 4D array the 4th being something which controls how many to skip? Or would the x-axis simply change altogether and have large gaps in between - for example [5][y][z] would skip 5 tiles? Is there something really obvious here which I am missing? The number of z levels I'm trying to have is around 66, it would be preferably that I can have up to or more than 1000 in x and y.

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  • Direct2D Transform

    - by James
    I have a beginner question about Direct2D transforms. I have a 20 x 10 bitmap that I would like to draw in different orientations. To start, I would like to draw it vertically with a destination rectangle of say: (left, top, right, bottom) (300, 300, 310, 320) The bitmap is wider than it is tall (20 x 10), but when I draw it vertically, it will be appear taller than it is wide (10 x 20). I know that I can use a rotation matrix like so: m_pRenderTarget->SetTransform( D2D1::Matrix3x2F::Rotation( 90.0f, D2D1::Point2F(<center of shape>)) ); But when I use this method to rotate my shape, the destination rectangle is still wider than it is tall. Maybe it would look something like this: (left, top, right, bottom) (280, 290, 300, 300) The destination rectangle is 20 x 10 but the bitmap appears on the screen as 10 x 20. I can't look at the destination rectangle in the debugger and compare it to: (left, top, right, bottom) (300, 300, 310, 320) Is there any simple way to say "I want to rotate it so that the image is rendered to exactly this destination rectangle after the rotation?" In this case, I would like to say "Please rotate the bitmap so that it appears on the screen at this location:" (left, top, right, bottom) (300, 300, 310, 320) If I can't do that, is there any way to find out the 10 x 20 destination rectangle where the bitmap is actually being rendered to the screen?

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  • OpenGL ES 2.0 texture distortion on large geometry

    - by Spruce
    OpenGL ES 2.0 has serious precision issues with texture sampling - I've seen topics with a similar problem, but I haven't seen a real solution to this "distorted OpenGL ES 2.0 texture" problem yet. This is not related to the texture's image format or OpenGL color buffers, it seems like it's a precision error. I don't know what specifically causes the precision to fail - it doesn't seem like it's just the size of geometry that causes this distortion, because simply scaling vertex position passed to the the vertex shader does not solve the issue. Here are some examples of the texture distortion: Distorted Texture (on OpenGL ES 2.0): http://i47.tinypic.com/3322h6d.png What the texture normally looks like (also on OpenGL ES 2.0): http://i49.tinypic.com/b4jc6c.png The texture issue is limited to small scale geometry on OpenGL ES 2.0, otherwise the texture sampling appears normal, but the grainy effect gradually worsens the further the vertex data is from the origin of XYZ(0,0,0) These texture issues do not occur on desktop OpenGL (works fine under Windows XP, Windows 7, and Mac OS X) I've only seen the problem occur on Android, iPhone, or WebGL(which is similar to OpenGL ES 2.0) All textures are power of 2 but the problem still occurs Scaling the vertex data - The values of a vertex's X Y Z location are in the range of: -65536 to +65536 floating point I realized this was large, so I tried dividing the vertex positions by 1024 to shrink the geometry and hopefully get more accurate floating point precision, but this didn't fix or lessen the texture distortion issue Scaling the modelview or scaling the projection matrix does not help Changing texture filtering options does not help Disabling mipmapping, or using GL_NEAREST/GL_LINEAR does nothing Enabling/disabling anisotropic does nothing The banding effect still occurs even when using GL_CLAMP Dividing the texture coords passed to the vertex shader and then multiplying them back to the correct values in the fragment shader, also does not work precision highp sampler2D, highp float, highp int - in the fragment or the vertex shader didn't change anything (lowp/mediump did not work either) I'm thinking this problem has to have been solved at one point - Seeing that OpenGL ES 2.0 -based games have been able to render large-scale, highly detailed geometry

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  • How to efficiently map tokens to code in a script interpreter?

    - by lithander
    I'm writing an interpreter for a simple scripting language where each line is a complete, executable command. (Like the instructions in assembler) When parsing a line I have to map the requested command to actual code. My current solution looks like this: std::string op, param1, param2; //parse line, identify op, param1, param2 ... //call command specific code if(op == "MOV") ExecuteMov(AsNumber(param1)); else if(op == "ROT") ExecuteRot(AsNumber(param1)); else if(op == "SZE") ExecuteSze(AsNumber(param1)); else if(op == "POS") ExecutePos((AsNumber(param1), AsNumber(param2)); else if(op == "DIR") ExecuteDir((AsNumber(param1), AsNumber(param2)); else if(op == "SET") ExecuteSet(param1, AsNumber(param2)); else if(op == "EVL") ... The more commands are supported the more string comparisions I'll have to do to identify and call the associated method. Can you point me to a more efficient implementation in the described scenario?

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  • Getting the number of fragments which passed the depth test

    - by Etan
    In "modern" environments, the "NV Occlusion Query" extension provides a method to get the number of fragments which passed the depth test. However, on the iPad / iPhone using OpenGL ES, the extension is not available. What is the most performant approach to implement a similar behaviour in the fragment shader? Some of my ideas: Render the object completely in white, then count all the colors together using a two-pass shader where first a vertical line is rendered and for each fragment the shader computes the sum over the whole row. Then, a single vertex is rendered whose fragment sums all the partial sums of the first pass. Doesn't seem to be very efficient. Render the object completely in white over a black background. Downsample recursively, abusing the hardware linear interpolation between textures until being at a reasonably small resolution. This leads to fragments which have a greyscale level depending on the number of white pixels where in their corresponding region. Is this even accurate enough? Use mipmaps and simply read the pixel on the 1x1 level. Again the question of accuracy and if it is even possible using non-power-of-two textures. The problem wit these approaches is, that the pipeline gets stalled which results in major performance issues. Therefore, I'm looking for a more performant way to accomplish my goal. Using the EXT_OCCLUSION_QUERY_BOOLEAN extension Apple introduced EXT_OCCLUSION_QUERY_BOOLEAN in iOS 5.0 for iPad 2. "4.1.6 Occlusion Queries Occlusion queries use query objects to track the number of fragments or samples that pass the depth test. An occlusion query can be started and finished by calling BeginQueryEXT and EndQueryEXT, respectively, with a target of ANY_SAMPLES_PASSED_EXT or ANY_SAMPLES_PASSED_CONSERVATIVE_EXT. When an occlusion query is started with the target ANY_SAMPLES_PASSED_EXT, the samples-boolean state maintained by the GL is set to FALSE. While that occlusion query is active, the samples-boolean state is set to TRUE if any fragment or sample passes the depth test. When the occlusion query finishes, the samples-boolean state of FALSE or TRUE is written to the corresponding query object as the query result value, and the query result for that object is marked as available. If the target of the query is ANY_SAMPLES_PASSED_CONSERVATIVE_EXT, an implementation may choose to use a less precise version of the test which can additionally set the samples-boolean state to TRUE in some other implementation dependent cases." The first sentence hints on a behavior which is exactly what I'm looking for: getting the number of pixels which passed the depth test in an asynchronous manner without much performance loss. However, the rest of the document describes only how to get boolean results. Is it possible to exploit this extension to get the pixel count? Does the hardware support it so that there may be hidden API to get access to the pixel count? Other extensions which could be exploitable would be debugging features like the number of times the fragment shader was invoked (PSInvocations in DirectX - not sure if something simila is available in OpenGL ES). However, this would also result in a pipeline stall.

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  • why is this rails association loading individually after an eager load?

    - by codeman73
    I'm trying to avoid the N+1 queries problem with eager loading, but it's not working. The associated models are still being loaded individually. Here are the relevant ActiveRecords and their relationships: class Player < ActiveRecord::Base has_one :tableau end Class Tableau < ActiveRecord::Base belongs_to :player has_many :tableau_cards has_many :deck_cards, :through => :tableau_cards end Class TableauCard < ActiveRecord::Base belongs_to :tableau belongs_to :deck_card, :include => :card end class DeckCard < ActiveRecord::Base belongs_to :card has_many :tableaus, :through => :tableau_cards end class Card < ActiveRecord::Base has_many :deck_cards end and the query I'm using is inside this method of Player: def tableau_contains(card_id) self.tableau.tableau_cards = TableauCard.find :all, :include => [ {:deck_card => (:card)}], :conditions => ['tableau_cards.tableau_id = ?', self.tableau.id] contains = false for tableau_card in self.tableau.tableau_cards # my logic here, looking at attributes of the Card model, with # tableau_card.deck_card.card; # individual loads of related Card models related to tableau_card are done here end return contains end Does it have to do with scope? This tableau_contains method is down a few method calls in a larger loop, where I originally tried doing the eager loading because there are several places where these same objects are looped through and examined. Then I eventually tried the code as it is above, with the load just before the loop, and I'm still seeing the individual SELECT queries for Card inside the tableau_cards loop in the log. I can see the eager-loading query with the IN clause just before the tableau_cards loop as well. EDIT: additional info below with the larger, outer loop Here's the larger loop. It is inside an observer on after_save def after_save(pa) @game = Game.find(turn.game_id, :include => :goals) @game.players = Player.find :all, :include => [ {:tableau => (:tableau_cards)}, :player_goals ], :conditions => ['players.game_id =?', @game.id] for player in @game.players player.tableau.tableau_cards = TableauCard.find :all, :include => [ {:deck_card => (:card)}], :conditions => ['tableau_cards.tableau_id = ?', player.tableau.id] if(player.tableau_contains(card)) ... end end end

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  • What is UVIndex and how do I use it on OpenGL?

    - by Delta
    I am a noob in OpenGL ES 2.0 (for WebGL) and I'm trying to draw a simple model I've made with a 3D tool and exported to .fbx format. I've been able to draw some models that only have: A vertex buffer, a index buffer for the vertices, a normal buffer and a texture coordinate buffer, but this model now has a "UVIndex" and I'm not sure where am I supposed to put this UVIndex. My code looks like this: GL.bindBuffer(GL.ARRAY_BUFFER, this.Model.House.VertexBuffer); GL.vertexAttribPointer(this.Shader.TextureAndLighting.Attribute["vPosition"],3,GL.FLOAT, false, 0, 0); GL.bindBuffer(GL.ARRAY_BUFFER, this.Model.House.NormalBuffer); GL.vertexAttribPointer(this.Shader.TextureAndLighting.Attribute["vNormal"], 3, GL.FLOAT, false, 0, 0); GL.bindBuffer(GL.ARRAY_BUFFER, this.Model.House.TexCoordBuffer); GL.vertexAttribPointer(this.Shader.TextureAndLighting.Attribute["TexCoord"], 2, GL.FLOAT, false, 0, 0); GL.bindBuffer(GL.ELEMENT_ARRAY_BUFFER, this.Model.House.IndexBuffer); GL.bindTexture(GL.TEXTURE_2D, this.Texture.HTex1); GL.activeTexture(GL.TEXTURE0); GL.drawElements(GL.TRIANGLES, this.Model.House.IndexBuffer.Length, GL.UNSIGNED_SHORT, 0); But my model renders totally incorrect and I think it has to do with the fact that I am ignoring this "UVIndex" in the .fbx file, since I've never drawn any model that uses this UVIndex I really have no clue on what to do with it. This is the json file containing the model's data: http://pastebin.com/raw.php?i=G294TVmz

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  • Problem with Ogre::Camera lookAt function when target is directly below.

    - by PigBen
    I am trying to make a class which controls a camera. It's pretty basic right now, it looks like this: class HoveringCameraController { public: void init(Ogre::Camera & camera, AnimatedBody & target, Ogre::Real height); void update(Ogre::Real time_delta); private: Ogre::Camera * camera_; AnimatedBody * target_; Ogre::Real height_; }; HoveringCameraController.cpp void HoveringCameraController::init(Ogre::Camera & camera, AnimatedBody & target, Ogre::Real height) { camera_ = &camera; target_ = &target; height_ = height; update(0.0); } void HoveringCameraController::update(Ogre::Real time_delta) { auto position = target_->getPosition(); position.y += height_; camera_->setPosition(position); camera_->lookAt(target_->getPosition()); } AnimatedBody is just a class that encapsulates an entity, it's animations and a scene node. The getPosition function is simply forwarded to it's scene node. What I want(for now) is for the camera to simply follow the AnimatedBody overhead at the distance given(the height parameter), and look down at it. It follows the object around, but it doesn't look straight down, it's tilted quite a bit in the positive Z direction. Does anybody have any idea why it would do that? If I change this line: position.y += height_; to this: position.x += height_; or this: position.z += height_; it does exactly what I would expect. It follows the object from the side or front, and looks directly at it.

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  • Continuous Movement of gun bullet

    - by Siddharth
    I was using box2d for the movement of the body. When I apply gravity (0,0) the bullet continuously move but when I change gravity to the earth the behavior was changed. I also try to apply continuous force to the bullet body but the behavior was not so good. So please provide any suggestion to continuously move bullet body in earth gravity. currentVelocity = bulletBody.getLinearVelocity(); if (currentVelocity.len() < speed|| currentVelocity.len() > speed + 0.25f) { velocityChange = Math.abs(speed - currentVelocity.len()); currentVelocity.set(currentVelocity.x* velocityChange, currentVelocity.y*velocityChange); bulletBody.applyLinearImpulse(currentVelocity,bulletBody.getWorldCenter()); } I apply above code for the continuous velocity of the body. And also I did not able to find any setGravityScale method in the library.

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