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  • OpenGL 3.x Assimp trouble implementing phong shading (normals?)

    - by Defcronyke
    I'm having trouble getting phong shading to look right. I'm pretty sure there's something wrong with either my OpenGL calls, or the way I'm loading my normals, but I guess it could be something else since 3D graphics and Assimp are both still very new to me. When trying to load .obj/.mtl files, the problems I'm seeing are: The models seem to be lit too intensely (less phong-style and more completely washed out, too bright). Faces that are lit seem to be lit equally all over (with the exception of a specular highlight showing only when the light source position is moved to be practically right on top of the model) Because of problems 1 and 2, spheres look very wrong: picture of sphere And things with larger faces look (less-noticeably) wrong too: picture of cube I could be wrong, but to me this doesn't look like proper phong shading. Here's the code that I think might be relevant (I can post more if necessary): file: assimpRenderer.cpp #include "assimpRenderer.hpp" namespace def { assimpRenderer::assimpRenderer(std::string modelFilename, float modelScale) { initSFML(); initOpenGL(); if (assImport(modelFilename)) // if modelFile loaded successfully { initScene(); mainLoop(modelScale); shutdownScene(); } shutdownOpenGL(); shutdownSFML(); } assimpRenderer::~assimpRenderer() { } void assimpRenderer::initSFML() { windowWidth = 800; windowHeight = 600; settings.majorVersion = 3; settings.minorVersion = 3; app = NULL; shader = NULL; app = new sf::Window(sf::VideoMode(windowWidth,windowHeight,32), "OpenGL 3.x Window", sf::Style::Default, settings); app->setFramerateLimit(240); app->setActive(); return; } void assimpRenderer::shutdownSFML() { delete app; return; } void assimpRenderer::initOpenGL() { GLenum err = glewInit(); if (GLEW_OK != err) { /* Problem: glewInit failed, something is seriously wrong. */ std::cerr << "Error: " << glewGetErrorString(err) << std::endl; } // check the OpenGL context version that's currently in use int glVersion[2] = {-1, -1}; glGetIntegerv(GL_MAJOR_VERSION, &glVersion[0]); // get the OpenGL Major version glGetIntegerv(GL_MINOR_VERSION, &glVersion[1]); // get the OpenGL Minor version std::cout << "Using OpenGL Version: " << glVersion[0] << "." << glVersion[1] << std::endl; return; } void assimpRenderer::shutdownOpenGL() { return; } void assimpRenderer::initScene() { // allocate heap space for VAOs, VBOs, and IBOs vaoID = new GLuint[scene->mNumMeshes]; vboID = new GLuint[scene->mNumMeshes*2]; iboID = new GLuint[scene->mNumMeshes]; glClearColor(0.4f, 0.6f, 0.9f, 0.0f); glEnable(GL_DEPTH_TEST); glDepthFunc(GL_LEQUAL); glEnable(GL_CULL_FACE); shader = new Shader("shader.vert", "shader.frag"); projectionMatrix = glm::perspective(60.0f, (float)windowWidth / (float)windowHeight, 0.1f, 100.0f); rot = 0.0f; rotSpeed = 50.0f; faceIndex = 0; colorArrayA = NULL; colorArrayD = NULL; colorArrayS = NULL; normalArray = NULL; genVAOs(); return; } void assimpRenderer::shutdownScene() { delete [] iboID; delete [] vboID; delete [] vaoID; delete shader; } void assimpRenderer::renderScene(float modelScale) { sf::Time elapsedTime = clock.getElapsedTime(); clock.restart(); if (rot > 360.0f) rot = 0.0f; rot += rotSpeed * elapsedTime.asSeconds(); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT); viewMatrix = glm::translate(glm::mat4(1.0f), glm::vec3(0.0f, -3.0f, -10.0f)); // move back a bit modelMatrix = glm::scale(glm::mat4(1.0f), glm::vec3(modelScale)); // scale model modelMatrix = glm::rotate(modelMatrix, rot, glm::vec3(0, 1, 0)); //modelMatrix = glm::rotate(modelMatrix, 25.0f, glm::vec3(0, 1, 0)); glm::vec3 lightPosition( 0.0f, -100.0f, 0.0f ); float lightPositionArray[3]; lightPositionArray[0] = lightPosition[0]; lightPositionArray[1] = lightPosition[1]; lightPositionArray[2] = lightPosition[2]; shader->bind(); int projectionMatrixLocation = glGetUniformLocation(shader->id(), "projectionMatrix"); int viewMatrixLocation = glGetUniformLocation(shader->id(), "viewMatrix"); int modelMatrixLocation = glGetUniformLocation(shader->id(), "modelMatrix"); int ambientLocation = glGetUniformLocation(shader->id(), "ambientColor"); int diffuseLocation = glGetUniformLocation(shader->id(), "diffuseColor"); int specularLocation = glGetUniformLocation(shader->id(), "specularColor"); int lightPositionLocation = glGetUniformLocation(shader->id(), "lightPosition"); int normalMatrixLocation = glGetUniformLocation(shader->id(), "normalMatrix"); glUniformMatrix4fv(projectionMatrixLocation, 1, GL_FALSE, &projectionMatrix[0][0]); glUniformMatrix4fv(viewMatrixLocation, 1, GL_FALSE, &viewMatrix[0][0]); glUniformMatrix4fv(modelMatrixLocation, 1, GL_FALSE, &modelMatrix[0][0]); glUniform3fv(lightPositionLocation, 1, lightPositionArray); for (unsigned int i = 0; i < scene->mNumMeshes; i++) { colorArrayA = new float[3]; colorArrayD = new float[3]; colorArrayS = new float[3]; material = scene->mMaterials[scene->mNumMaterials-1]; normalArray = new float[scene->mMeshes[i]->mNumVertices * 3]; unsigned int normalIndex = 0; for (unsigned int j = 0; j < scene->mMeshes[i]->mNumVertices * 3; j+=3, normalIndex++) { normalArray[j] = scene->mMeshes[i]->mNormals[normalIndex].x; // x normalArray[j+1] = scene->mMeshes[i]->mNormals[normalIndex].y; // y normalArray[j+2] = scene->mMeshes[i]->mNormals[normalIndex].z; // z } normalIndex = 0; glUniformMatrix3fv(normalMatrixLocation, 1, GL_FALSE, normalArray); aiColor3D ambient(0.0f, 0.0f, 0.0f); material->Get(AI_MATKEY_COLOR_AMBIENT, ambient); aiColor3D diffuse(0.0f, 0.0f, 0.0f); material->Get(AI_MATKEY_COLOR_DIFFUSE, diffuse); aiColor3D specular(0.0f, 0.0f, 0.0f); material->Get(AI_MATKEY_COLOR_SPECULAR, specular); colorArrayA[0] = ambient.r; colorArrayA[1] = ambient.g; colorArrayA[2] = ambient.b; colorArrayD[0] = diffuse.r; colorArrayD[1] = diffuse.g; colorArrayD[2] = diffuse.b; colorArrayS[0] = specular.r; colorArrayS[1] = specular.g; colorArrayS[2] = specular.b; // bind color for each mesh glUniform3fv(ambientLocation, 1, colorArrayA); glUniform3fv(diffuseLocation, 1, colorArrayD); glUniform3fv(specularLocation, 1, colorArrayS); // render all meshes glBindVertexArray(vaoID[i]); // bind our VAO glDrawElements(GL_TRIANGLES, scene->mMeshes[i]->mNumFaces*3, GL_UNSIGNED_INT, 0); glBindVertexArray(0); // unbind our VAO delete [] normalArray; delete [] colorArrayA; delete [] colorArrayD; delete [] colorArrayS; } shader->unbind(); app->display(); return; } void assimpRenderer::handleEvents() { sf::Event event; while (app->pollEvent(event)) { if (event.type == sf::Event::Closed) { app->close(); } if ((event.type == sf::Event::KeyPressed) && (event.key.code == sf::Keyboard::Escape)) { app->close(); } if (event.type == sf::Event::Resized) { glViewport(0, 0, event.size.width, event.size.height); } } return; } void assimpRenderer::mainLoop(float modelScale) { while (app->isOpen()) { renderScene(modelScale); handleEvents(); } } bool assimpRenderer::assImport(const std::string& pFile) { // read the file with some example postprocessing scene = importer.ReadFile(pFile, aiProcess_CalcTangentSpace | aiProcess_Triangulate | aiProcess_JoinIdenticalVertices | aiProcess_SortByPType); // if the import failed, report it if (!scene) { std::cerr << "Error: " << importer.GetErrorString() << std::endl; return false; } return true; } void assimpRenderer::genVAOs() { int vboIndex = 0; for (unsigned int i = 0; i < scene->mNumMeshes; i++, vboIndex+=2) { mesh = scene->mMeshes[i]; indexArray = new unsigned int[mesh->mNumFaces * sizeof(unsigned int) * 3]; // convert assimp faces format to array faceIndex = 0; for (unsigned int t = 0; t < mesh->mNumFaces; ++t) { const struct aiFace* face = &mesh->mFaces[t]; std::memcpy(&indexArray[faceIndex], face->mIndices, sizeof(float) * 3); faceIndex += 3; } // generate VAO glGenVertexArrays(1, &vaoID[i]); glBindVertexArray(vaoID[i]); // generate IBO for faces glGenBuffers(1, &iboID[i]); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, iboID[i]); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(GLuint) * mesh->mNumFaces * 3, indexArray, GL_STATIC_DRAW); // generate VBO for vertices if (mesh->HasPositions()) { glGenBuffers(1, &vboID[vboIndex]); glBindBuffer(GL_ARRAY_BUFFER, vboID[vboIndex]); glBufferData(GL_ARRAY_BUFFER, mesh->mNumVertices * sizeof(GLfloat) * 3, mesh->mVertices, GL_STATIC_DRAW); glEnableVertexAttribArray((GLuint)0); glVertexAttribPointer((GLuint)0, 3, GL_FLOAT, GL_FALSE, 0, 0); } // generate VBO for normals if (mesh->HasNormals()) { normalArray = new float[scene->mMeshes[i]->mNumVertices * 3]; unsigned int normalIndex = 0; for (unsigned int j = 0; j < scene->mMeshes[i]->mNumVertices * 3; j+=3, normalIndex++) { normalArray[j] = scene->mMeshes[i]->mNormals[normalIndex].x; // x normalArray[j+1] = scene->mMeshes[i]->mNormals[normalIndex].y; // y normalArray[j+2] = scene->mMeshes[i]->mNormals[normalIndex].z; // z } normalIndex = 0; glGenBuffers(1, &vboID[vboIndex+1]); glBindBuffer(GL_ARRAY_BUFFER, vboID[vboIndex+1]); glBufferData(GL_ARRAY_BUFFER, mesh->mNumVertices * sizeof(GLfloat) * 3, normalArray, GL_STATIC_DRAW); glEnableVertexAttribArray((GLuint)1); glVertexAttribPointer((GLuint)1, 3, GL_FLOAT, GL_FALSE, 0, 0); delete [] normalArray; } // tex coord stuff goes here // unbind buffers glBindVertexArray(0); glBindBuffer(GL_ARRAY_BUFFER, 0); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); delete [] indexArray; } vboIndex = 0; return; } } file: shader.vert #version 150 core in vec3 in_Position; in vec3 in_Normal; uniform mat4 projectionMatrix; uniform mat4 viewMatrix; uniform mat4 modelMatrix; uniform vec3 lightPosition; uniform mat3 normalMatrix; smooth out vec3 vVaryingNormal; smooth out vec3 vVaryingLightDir; void main() { // derive MVP and MV matrices mat4 modelViewProjectionMatrix = projectionMatrix * viewMatrix * modelMatrix; mat4 modelViewMatrix = viewMatrix * modelMatrix; // get surface normal in eye coordinates vVaryingNormal = normalMatrix * in_Normal; // get vertex position in eye coordinates vec4 vPosition4 = modelViewMatrix * vec4(in_Position, 1.0); vec3 vPosition3 = vPosition4.xyz / vPosition4.w; // get vector to light source vVaryingLightDir = normalize(lightPosition - vPosition3); // Set the position of the current vertex gl_Position = modelViewProjectionMatrix * vec4(in_Position, 1.0); } file: shader.frag #version 150 core out vec4 out_Color; uniform vec3 ambientColor; uniform vec3 diffuseColor; uniform vec3 specularColor; smooth in vec3 vVaryingNormal; smooth in vec3 vVaryingLightDir; void main() { // dot product gives us diffuse intensity float diff = max(0.0, dot(normalize(vVaryingNormal), normalize(vVaryingLightDir))); // multiply intensity by diffuse color, force alpha to 1.0 out_Color = vec4(diff * diffuseColor, 1.0); // add in ambient light out_Color += vec4(ambientColor, 1.0); // specular light vec3 vReflection = normalize(reflect(-normalize(vVaryingLightDir), normalize(vVaryingNormal))); float spec = max(0.0, dot(normalize(vVaryingNormal), vReflection)); if (diff != 0) { float fSpec = pow(spec, 128.0); // Set the output color of our current pixel out_Color.rgb += vec3(fSpec, fSpec, fSpec); } } I know it's a lot to look through, but I'm putting most of the code up so as not to assume where the problem is. Thanks in advance to anyone who has some time to help me pinpoint the problem(s)! I've been trying to sort it out for two days now and I'm not getting anywhere on my own.

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  • Interesting Scala typing solution, doesn't work in 2.7.7?

    - by djc
    I'm trying to build some image algebra code that can work with images (basically a linear pixel buffer + dimensions) that have different types for the pixel. To get this to work, I've defined a parametrized Pixel trait with a few methods that should be able to get used with any Pixel subclass. (For now, I'm only interested in operations that work on the same Pixel type.) Here it is: trait Pixel[T <: Pixel[T]] { def mul(v: Double): T def max(v: T): T def div(v: Double): T def div(v: T): T } Now I define a single Pixel type that has storage based on three doubles (basically RGB 0.0-1.0), I've called it TripleDoublePixel: class TripleDoublePixel(v: Array[Double]) extends Pixel[TripleDoublePixel] { var data: Array[Double] = v def this() = this(Array(0.0, 0.0, 0.0)) def toString(): String = { "(" + data(0) + ", " + data(1) + ", " + data(2) + ")" } def increment(v: TripleDoublePixel) { data(0) += v.data(0) data(1) += v.data(1) data(2) += v.data(2) } def mul(v: Double): TripleDoublePixel = { new TripleDoublePixel(data.map(x => x * v)) } def div(v: Double): TripleDoublePixel = { new TripleDoublePixel(data.map(x => x / v)) } def div(v: TripleDoublePixel): TripleDoublePixel = { var tmp = new Array[Double](3) tmp(0) = data(0) / v.data(0) tmp(1) = data(1) / v.data(1) tmp(2) = data(2) / v.data(2) new TripleDoublePixel(tmp) } def max(v: TripleDoublePixel): TripleDoublePixel = { val lv = data(0) * data(0) + data(1) * data(1) + data(2) * data(2) val vv = v.data(0) * v.data(0) + v.data(1) * v.data(1) + v.data(2) * v.data(2) if (lv > vv) (this) else v } } Now I want to write code to use this, that doesn't have to know what type the pixels are. For example: def idiv[T](a: Image[T], b: Image[T]) { for (i <- 0 until a.data.size) { a.data(i) = a.data(i).div(b.data(i)) } } Unfortunately, this doesn't compile: (fragment of lindet-gen.scala):145: error: value div is not a member of T a.data(i) = a.data(i).div(b.data(i)) I was told in #scala that this worked for someone else, but that was on 2.8. I've tried to get 2.8-rc1 going, but it doesn't compile for me. Is there any way to get this to work in 2.7.7?

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  • Where should I place my reaction code in Per-Pixel Collision Detection?

    - by CJ Cohorst
    I have this collision detection code: public bool PerPixelCollision(Player player, Game1 dog) { Matrix atob = player.Transform * Matrix.Invert(dog.Transform); Vector2 stepX = Vector2.TransformNormal(Vector2.UnitX, atob); Vector2 stepY = Vector2.TransformNormal(Vector2.UnitY, atob); Vector2 iBPos = Vector2.Transform(Vector2.Zero, atob); for(int deltax = 0; deltax < player.playerTexture.Width; deltax++) { Vector2 bpos = iBPos; for (int deltay = 0; deltay < player.playerTexture.Height; deltay++) { int bx = (int)bpos.X; int by = (int)bpos.Y; if (bx >= 0 && bx < dog.dogTexture.Width && by >= 0 && by < dog.dogTexture.Height) { if (player.TextureData[deltax + deltay * player.playerTexture.Width].A > 150 && dog.TextureData[bx + by * dog.Texture.Width].A > 150) { return true; } } bpos += stepY; } iBPos += stepX; } return false; } What I want to know is where to put in the code where something happens. For example, I want to put in player.playerPosition.X -= 200 just as a test, but I don't know where to put it. I tried putting it under the return true and above it, but under it, it said unreachable code, and above it nothing happened. I also tried putting it by bpos += stepY; but that didn't work either. Where do I put the code?

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  • Html5: How to handle RGB pixel with commands from prompt ? (just a browser)

    - by Rocket Surgeon
    In the browser tools, say in debugging (any browser will do, but IE9 preferred) how can I access things like html5 canvas and modify individual pixels by typing commands from prompt ? I know, it is possible to accomplish in miriad normal ways with preparing the markup and loading the page, but what is the shortest path ? The browser is running with some content, then I hit F12-Console- what exactly should I type to cause a canvas to change ? Thank you

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  • How do GameEngines stop Pixel Seams appearing in adjacent mesh boundaries due to FP imprecision?

    - by ufomorace
    Graphics cards are mathematically imprecise. So when some meshes are joined by their borders, the graphics card often makes mistakes and decides that some pixels at the seam represent neither object, and unwanted pixels appear. It's a natural behaviour on all graphics cards. How are such worries avoided in Pro Games? Batching? Shaders? Different tangent vectors? Merging? Overlaping seams? Dark backgrounds? Extra vertices at borders? Z precision? Camera distance tweaks? Screencap of a fix that ended up not working:

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  • How can I draw crisp per-pixel images with OpenGL ES on Android?

    - by Qasim
    I have made many Android applications and games in Java before, however I am very new to OpenGL ES. Using guides online, I have made simple things in OpenGL ES, including a simple triangle and a cube. I would like to make a 2D game with OpenGL ES, but what I've been doing isn't working quite so well, as the images I draw aren't to scale, and no matter what guide I use, the image is always choppy and not the right size (I'm debugging on my Nexus S). How can I draw crisp, HD images to the screen with GL ES? Here is an example of what happens when I try to do it: And the actual image: Here is how my texture is created: //get id int id = -1; gl.glGenTextures(1, texture, 0); id = texture[0]; //get bitmap Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.ball); //parameters gl.glBindTexture(GL10.GL_TEXTURE_2D, id); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE); gl.glTexEnvf(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE, GL10.GL_REPLACE); GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0); //crop image mCropWorkspace[0] = 0; mCropWorkspace[1] = height; mCropWorkspace[2] = width; mCropWorkspace[3] = -height; ((GL11) gl).glTexParameteriv(GL10.GL_TEXTURE_2D, GL11Ext.GL_TEXTURE_CROP_RECT_OES, mCropWorkspace, 0);

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  • How can I ease the work of getting pixel coordinates from a spritesheet?

    - by ThePlan
    When it comes to spritesheets they're usually easier to use, and they're very efficient memory-wise, but the problem that I'm always having is getting the actual position of a sprite from a sheet. Usually, I have to throw in some aproximated values and modify them several times until I get it right. My question: is there a tool which can basically show you the coordinates of the mouse relative to the image you have opened? Or is there a simpler method of getting the exact rectangle that the sprite is contained in?

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  • How can I stop pixel seams appearing in adjacent mesh boundaries due to floating point imprecision?

    - by ufomorace
    Graphics cards are mathematically imprecise. So when some meshes are joined by their borders, the graphics card often makes mistakes and decides that some pixels at the seam represent neither object, and unwanted pixels appear. It's a natural behaviour on all graphics cards. How are such worries avoided in Pro Games? Batching? Shaders? Different tangent vectors? Merging? Overlaping seams? Dark backgrounds? Extra vertices at borders? Z precision? Camera distance tweaks? Screencap of a fix that ended up not working:

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  • How do professional games avoid showing pixel seams in adjacent mesh boundaries due to decimal imprecision?

    - by ufomorace
    Graphics cards are mathematically imprecise. So when some meshes are joined by their borders, the graphics card often makes mistakes and decides that some pixels at the seam represent neither object, and unwanted pixels appear. It's a natural behaviour on all graphics cards. How are such worries avoided in Pro Games? Batching? Shaders? Different tangent vectors? Merging? Overlaping seams? Dark backgrounds? Extra vertices at borders? Z precision? Camera distance tweaks? Screencap of a fix that ended up not working:

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  • How to draw an RGB pixel with bare hands ? (no extra document just a browser)

    - by Rocket Surgeon
    In the browser tools, say in debugging (any browser will do, but IE9 preferred) how can I access things like html5 canvas and modify individual pixels by typing commands from prompt ? I know, it is possible to accomplish in miriad normal ways with preparing the markup and loading the page, but what is the shortest path ? The browser is running with some content, then I hit F12-Console- what exactly should I type to cause a canvas to change ? Thank you

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  • Discovering path through unknown territory

    - by TravisG
    Let's say all the AI knows about it's surroundings is a pixel-map that it has which clearly shows walkable terrain and obstacles. I want the AI to be able to traverse this terrain until it finds an exit point. There are some restrictions: There is always a way to the exit in the entire map that the AI walks around in, but there may be dead ends. The path to the exit is always pretty random, meaning that if you stand at crossroads, nothing indicates which direction would be the right one to go. It doesn't matter if the AI reaches a dead end, but it has to be able walk back out of it to a previously not inspected location and continue its search there. Initially, the AI starts out knowing only the starting area of the whole map. As it walks around, new points will be added to the pixel-map as the AI corresponding to the AIs range of sight (think of it like the AI is clearing the fog of war) The problem is in 2D space. All I have is the pixel map. There are no paths in the pixel map which are "too narrow". The AI fits through everything. It shouldn't be a brute force solution. E.g. it would be possible to simply find a path to each pixel in the pixel map that is yet undiscovered (with A*, for example), which will lead to the AI discovering new pixels. This could be repeated until the end is reached. The path doesn't have to be the shortest path (this is impossible without knowing the entire map beforehand), but when movements within the visible area are calculated, the shortest and from a human standpoint most logical path should be taken (e.g. if you can see a way out of your room into a hallway, you would obviously go there instead of exploring the corner of your current room). What kind of approaches to solve this problem are there?

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  • Is there a program that compares image files and reports if they are exactly the same pixel-wise?

    - by Nathaniel Drake
    I'm making a regression testing suite for some rendering software. I need to be able to load an image file (PNG or TGA, ideally) and compare the pixel values to a standard approved image. I'd like it to be command line driven too, so I can make a batch file to run all the tests. All the compare utilities I have found so far either show differences (I just need it to fail if they are different) or compare all the bytes, meaning that meta-data will trigger a fail. Anyone got any suggestions? I am not a coder, and can only barely cobble a batch script together. Thanks for any suggestions.

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  • Rails + AMcharts (with export image php script) - PHP script converted to controller?

    - by Elliot
    Hey Guys, This one might be a little confusing. I'm using AMCharts with rails. Amcharts comes with a PHP script to export images called "export.php" I'm trying to figure out how to take the code in export.php and put it into a controller. Here is the code: <?php // amcharts.com export to image utility // set image type (gif/png/jpeg) $imgtype = 'jpeg'; // set image quality (from 0 to 100, not applicable to gif) $imgquality = 100; // get data from $_POST or $_GET ? $data = &$_POST; // get image dimensions $width = (int) $data['width']; $height = (int) $data['height']; // create image object $img = imagecreatetruecolor($width, $height); // populate image with pixels for ($y = 0; $y < $height; $y++) { // innitialize $x = 0; // get row data $row = explode(',', $data['r'.$y]); // place row pixels $cnt = sizeof($row); for ($r = 0; $r < $cnt; $r++) { // get pixel(s) data $pixel = explode(':', $row[$r]); // get color $pixel[0] = str_pad($pixel[0], 6, '0', STR_PAD_LEFT); $cr = hexdec(substr($pixel[0], 0, 2)); $cg = hexdec(substr($pixel[0], 2, 2)); $cb = hexdec(substr($pixel[0], 4, 2)); // allocate color $color = imagecolorallocate($img, $cr, $cg, $cb); // place repeating pixels $repeat = isset($pixel[1]) ? (int) $pixel[1] : 1; for ($c = 0; $c < $repeat; $c++) { // place pixel imagesetpixel($img, $x, $y, $color); // iterate column $x++; } } } // set proper content type header('Content-type: image/'.$imgtype); header('Content-Disposition: attachment; filename="chart.'.$imgtype.'"'); // stream image $function = 'image'.$imgtype; if ($imgtype == 'gif') { $function($img); } else { $function($img, null, $imgquality); } // destroy imagedestroy($img); ?>

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  • Zooming in isometric engine using XNA

    - by Yheeky
    I´m currently working on an isometric game engine and right now I´m looking for help concerning my zoom function. On my tilemap there are several objects, some of them are selectable. When a house (texture size 128 x 256) is placed on the map I create an array containing all pixels (= 32768 pixels). Therefore each pixel has an alpha value I check if the value is bigger than 200 so it seems to be a pixel which belongs to the building. So if the mouse cursor is on this pixel the building will be selected - PixelCollision. Now I´ve already implemented my zooming function which works quite well. I use a scale variable which will change my calculation on drawing all map items. What I´m looking for right now is a precise way to find out if a zoomed out/in house is selected. My formula works for values like 0,5 (zoomed out) or 2 (zoomed in) but not for in between. Here is the code I use for the pixel index: var pixelIndex = (int)(((yPos / (Scale * Scale)) * width) + (xPos / Scale) + 1); Example: Let´s assume my mouse is over pixel coordinate 38/222 on the original house texture. Using the code above we get the following pixel index. var pixelIndex = ((222 / (1 * 1)) * 128) + (38 / 1) + 1; = (222 * 128) + 39 = 28416 + 39 = 28455 If we now zoom out to scale 0,5, the texture size will change to 64 x 128 and the amount of pixels will decrease from 32768 to 8192. Of course also our mouse point changes by the scale to 19/111. The formula makes it easy to calculate the original pixelIndex using our new coordinates: var pixelIndex = ((111 / (0.5 * 0.5)) * 64) + (19 / 0.5) + 1; = (444 * 64) + 39 = 28416 + 39 = 28455 But now comes the problem. If I zoom out just to scale 0.75 it does not work any more. The pixel amount changes from 32768 to 18432 pixels since texture size is 96 x 192. Mouse point is transformed to point 28/166. The formula gives me a wrong pixelIndex. var pixelIndex = ((166 / (0.75 * 0.75)) * 96) + (28 / 0.75) + 1; = (295.11 * 96) + 38.33 = 28330.66 + 38.33 = 28369 Does anyone have a clue what´s wrong in my code? Must be the first part (28330.66) which causes the calculation problem. Thanks! Yheeky

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  • How to retrieve a pixel in a tiff image (loaded with JAI)?

    - by Ed Taylor
    I'm using a class (DisplayContainer) to hold a RenderedOp-image that should be displayed to the user: RenderedOp image1 = JAI.create("tiff", params); DisplayContainer d = new DisplayContainer(image1); JScrollPane jsp = new JScrollPane(d); // Create a frame to contain the panel. Frame window = new Frame(); window.add(jsp); window.pack(); window.setVisible(true); The class DisplayContainer looks like this: import java.awt.event.MouseEvent; import java.awt.geom.AffineTransform; import javax.media.jai.RenderedOp; import com.sun.media.jai.widget.DisplayJAI; public class DisplayContainer extends DisplayJAI { private static final long serialVersionUID = 1L; private RenderedOp img; // Affine tranform private final float ratio = 1f; private AffineTransform scaleForm = AffineTransform.getScaleInstance(ratio, ratio); public DisplayContainer(RenderedOp img) { super(img); this.img = img; addMouseListener(this); } public void mouseClicked(MouseEvent e) { System.out.println("Mouseclick at: (" + e.getX() + ", " + e.getY() + ")"); // How to retrieve the RGB-value of the pixel where the click took // place? } // OMISSIONS } What I would like to know is how the RGB value of the clicked pixel can be obtained?

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  • Populating a color array with every 8th pixel in an image. C#

    - by Piper
    I have an image that is 512x280 pixels. I want to populate a 64x35 array with every 8th pixel in the matrix. Here is what I have right now: Color[,] imgArray = new Color[b.Width, b.Height]; for (int y = 0; y < 35; y++) { for (int x = 0; x < 64; x++) { imgArray[x, y] = b.GetPixel(x, y); } } But that will get just the top corner of the image. How would I change the loop so it grabs every 8th pixel to fill the array with? edit: I think I may have gotten it. Can someone read this and assure me that it is correct? Color[,] imgArray = new Color[64, 35]; for (int y = 0; y < 280; y+=8) { for (int x = 0; x < 512; x+=8) { imgArray[x, y] = b.GetPixel(x, y); } }

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  • DirectCompute

    In my previous blog post I introduced the concept of GPGPU ending with:On Windows, there is already a cross-GPU-vendor way of programming GPUs and that is the Direct X API. Specifically, on Windows Vista and Windows 7, the DirectX 11 API offers a dedicated subset of the API for GPGPU programming: DirectCompute. You use this API on the CPU side, to set up and execute the kernels on the GPU. The kernels are written in a language called HLSL (High Level Shader Language). You can use DirectCompute with HLSL to write a "compute shader", which is the term DirectX uses for what I've been referring to in this post as "kernel".In this post I want to share some links to get you started with DirectCompute and HLSL.1. Watch the recording of the PDC 09 session: DirectX11 DirectCompute.2. If session recordings is your thing there are two more on DirectCompute from nvidia's GTC09 conference 1015 (pdf, mp4) and 1411 (mp4 plus the presenter's written version of the session).3. Over at gamedev there is an old Compute Shader tutorial. At the same site, there is a 3-part blog post on Compute Shader: Introduction, Resources and Addressing.4. From PDC, you can also download the DirectCompute Hands On Lab.5. When you are ready to get your hands even dirtier, download the latest Windows DirectX SDK (at the time of writing the latest is dated Feb 2010).6. Within the SDK you'll find a Compute Shader Overview and samples such as: Basic, Sort, OIT, NBodyGravity, HDR Tone Mapping.7. Talking of DX11/DirectCompute samples, there are also a couple of good ones on this URL.8. The documentation of the various APIs is available online. Here are just some good (but far from complete) taster entry points into that: numthreads, SV_DispatchThreadID, SV_GroupThreadID, SV_GroupID, SV_GroupIndex, D3D11CreateDevice, D3DX11CompileFromFile, CreateComputeShader, Dispatch, D3D11_BIND_FLAG, GSSetShader. Comments about this post welcome at the original blog.

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  • gl_PointCoord always zero

    - by Jonathan
    I am trying to draw point sprites in OpenGL with a shader but gl_PointCoord is always zero. Here is my code Setup: //Shader creation..(includes glBindAttribLocation(program, ATTRIB_P, "p");) glEnableVertexAttribArray(ATTRIB_P); In the rendering loop: glUseProgram(shader_particles); float vertices[]={0.0f,0.0f,0.0f}; glEnable(GL_TEXTURE_2D); glEnable(GL_POINT_SPRITE); glEnable(GL_VERTEX_PROGRAM_POINT_SIZE); //glTexEnvi(GL_POINT_SPRITE, GL_COORD_REPLACE, GL_TRUE);(tried with this on/off, doesn't work) glVertexAttribPointer(ATTRIB_P, 3, GL_FLOAT, GL_FALSE, 0, vertices); glDrawArrays(GL_POINTS, 0, 1); Vertex Shader: attribute highp vec4 p; void main() { gl_PointSize = 40.0f; gl_Position = p; } Fragment Shader: void main() { gl_FragColor = vec4(gl_PointCoord.st, 0, 1);//if the coords range from 0-1, this should draw a square with black,red,green,yellow corners } But this only draws a black square with a size of 40. What am I doing wrong? Edit: Point sprites work when i use the fixed function, but I need to use shaders because in the end the code will be for opengl es 2.0 glUseProgram(0); glEnable(GL_TEXTURE_2D); glEnable(GL_POINT_SPRITE); glTexEnvi(GL_POINT_SPRITE, GL_COORD_REPLACE, GL_TRUE); glPointSize(40); glBegin(GL_POINTS); glVertex3f(0.0f,0.0f,0.0f); glEnd(); Is anyone able to get point sprites working with shader? If so, please share some code.

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  • Problem loading shaders with slimdx

    - by Levi
    I'm attempting to load an FX file in slimdx, I've got this exact FX file loading and compiling fine with XNA 4.0 but I'm getting errors with slimdx, here's my code to load it. using SlimDX.Direct3D11; using SlimDX.D3DCompiler; public static Effect LoadFXShader(string path) { Effect shader; using (var bytecode = ShaderBytecode.CompileFromFile(path, null, "fx_2_0", ShaderFlags.None, EffectFlags.None)) shader = new Effect(Devices.GPU.GraphicsDevice, bytecode); return shader; } Here's the shader: #define TEXTURE_TILE_SIZE 16 struct VertexToPixel { float4 Position : POSITION; float2 TextureCoords: TEXCOORD1; }; struct PixelToFrame { float4 Color : COLOR0; }; //------- Constants -------- float4x4 xView; float4x4 xProjection; float4x4 xWorld; float4x4 preViewProjection; //float random; //------- Texture Samplers -------- Texture TextureAtlas; sampler TextureSampler = sampler_state { texture = <TextureAtlas>; magfilter = Point; minfilter = point; mipfilter=linear; AddressU = mirror; AddressV = mirror;}; //------- Technique: Textured -------- VertexToPixel TexturedVS( byte4 inPos : POSITION, float2 inTexCoords: TEXCOORD0) { inPos.w = 1; VertexToPixel Output = (VertexToPixel)0; float4x4 preViewProjection = mul (xView, xProjection); float4x4 preWorldViewProjection = mul (xWorld, preViewProjection); Output.Position = mul(inPos, preWorldViewProjection); Output.TextureCoords = inTexCoords / TEXTURE_TILE_SIZE; return Output; } PixelToFrame TexturedPS(VertexToPixel PSIn) { PixelToFrame Output = (PixelToFrame)0; Output.Color = tex2D(TextureSampler, PSIn.TextureCoords); if(Output.Color.a != 1) clip(-1); return Output; } technique Textured { pass Pass0 { VertexShader = compile vs_2_0 TexturedVS(); PixelShader = compile ps_2_0 TexturedPS(); } } Now this exact shader works fine in XNA, but in slimdx I get the error ChunkDefault.fx(28,27): error X3000: unrecognized identifier 'byte4'

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  • Vertex buffer acting strange? [on hold]

    - by Ryan Capote
    I'm having a strange problem, and I don't know what could be causing it. My current code is identical to how I've done this before. I'm trying to render a rectangle using VBO and orthographic projection.   My results:     What I expect: 3x3 rectangle in the top left corner   #include <stdio.h> #include <GL\glew.h> #include <GLFW\glfw3.h> #include "lodepng.h"   static const int FALSE = 0; static const int TRUE = 1;   static const char* VERT_SHADER =     "#version 330\n"       "layout(location=0) in vec4 VertexPosition; "     "layout(location=1) in vec2 UV;"     "uniform mat4 uProjectionMatrix;"     /*"out vec2 TexCoords;"*/       "void main(void) {"     "    gl_Position = uProjectionMatrix*VertexPosition;"     /*"    TexCoords = UV;"*/     "}";   static const char* FRAG_SHADER =     "#version 330\n"       /*"uniform sampler2D uDiffuseTexture;"     "uniform vec4 uColor;"     "in vec2 TexCoords;"*/     "out vec4 FragColor;"       "void main(void) {"    /* "    vec4 texel = texture2D(uDiffuseTexture, TexCoords);"     "    if(texel.a <= 0) {"     "         discard;"     "    }"     "    FragColor = texel;"*/     "    FragColor = vec4(1.f);"     "}";   static int g_running; static GLFWwindow *gl_window; static float gl_projectionMatrix[16];   /*     Structures */ typedef struct _Vertex {     float x, y, z, w;     float u, v; } Vertex;   typedef struct _Position {     float x, y; } Position;   typedef struct _Bitmap {     unsigned char *pixels;     unsigned int width, height; } Bitmap;   typedef struct _Texture {     GLuint id;     unsigned int width, height; } Texture;   typedef struct _VertexBuffer {     GLuint bufferObj, vertexArray; } VertexBuffer;   typedef struct _ShaderProgram {     GLuint vertexShader, fragmentShader, program; } ShaderProgram;   /*   http://en.wikipedia.org/wiki/Orthographic_projection */ void createOrthoProjection(float *projection, float width, float height, float far, float near)  {       const float left = 0;     const float right = width;     const float top = 0;     const float bottom = height;          projection[0] = 2.f / (right - left);     projection[1] = 0.f;     projection[2] = 0.f;     projection[3] = -(right+left) / (right-left);     projection[4] = 0.f;     projection[5] = 2.f / (top - bottom);     projection[6] = 0.f;     projection[7] = -(top + bottom) / (top - bottom);     projection[8] = 0.f;     projection[9] = 0.f;     projection[10] = -2.f / (far-near);     projection[11] = (far+near)/(far-near);     projection[12] = 0.f;     projection[13] = 0.f;     projection[14] = 0.f;     projection[15] = 1.f; }   /*     Textures */ void loadBitmap(const char *filename, Bitmap *bitmap, int *success) {     int error = lodepng_decode32_file(&bitmap->pixels, &bitmap->width, &bitmap->height, filename);       if (error != 0) {         printf("Failed to load bitmap. ");         printf(lodepng_error_text(error));         success = FALSE;         return;     } }   void destroyBitmap(Bitmap *bitmap) {     free(bitmap->pixels); }   void createTexture(Texture *texture, const Bitmap *bitmap) {     texture->id = 0;     glGenTextures(1, &texture->id);     glBindTexture(GL_TEXTURE_2D, texture);       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);       glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bitmap->width, bitmap->height, 0,              GL_RGBA, GL_UNSIGNED_BYTE, bitmap->pixels);       glBindTexture(GL_TEXTURE_2D, 0); }   void destroyTexture(Texture *texture) {     glDeleteTextures(1, &texture->id);     texture->id = 0; }   /*     Vertex Buffer */ void createVertexBuffer(VertexBuffer *vertexBuffer, Vertex *vertices) {     glGenBuffers(1, &vertexBuffer->bufferObj);     glGenVertexArrays(1, &vertexBuffer->vertexArray);     glBindVertexArray(vertexBuffer->vertexArray);       glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer->bufferObj);     glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * 6, (const GLvoid*)vertices, GL_STATIC_DRAW);       const unsigned int uvOffset = sizeof(float) * 4;       glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), 0);     glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)uvOffset);       glEnableVertexAttribArray(0);     glEnableVertexAttribArray(1);       glBindBuffer(GL_ARRAY_BUFFER, 0);     glBindVertexArray(0); }   void destroyVertexBuffer(VertexBuffer *vertexBuffer) {     glDeleteBuffers(1, &vertexBuffer->bufferObj);     glDeleteVertexArrays(1, &vertexBuffer->vertexArray); }   void bindVertexBuffer(VertexBuffer *vertexBuffer) {     glBindVertexArray(vertexBuffer->vertexArray);     glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer->bufferObj); }   void drawVertexBufferMode(GLenum mode) {     glDrawArrays(mode, 0, 6); }   void drawVertexBuffer() {     drawVertexBufferMode(GL_TRIANGLES); }   void unbindVertexBuffer() {     glBindVertexArray(0);     glBindBuffer(GL_ARRAY_BUFFER, 0); }   /*     Shaders */ void compileShader(ShaderProgram *shaderProgram, const char *vertexSrc, const char *fragSrc) {     GLenum err;     shaderProgram->vertexShader = glCreateShader(GL_VERTEX_SHADER);     shaderProgram->fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);       if (shaderProgram->vertexShader == 0) {         printf("Failed to create vertex shader.");         return;     }       if (shaderProgram->fragmentShader == 0) {         printf("Failed to create fragment shader.");         return;     }       glShaderSource(shaderProgram->vertexShader, 1, &vertexSrc, NULL);     glCompileShader(shaderProgram->vertexShader);     glGetShaderiv(shaderProgram->vertexShader, GL_COMPILE_STATUS, &err);       if (err != GL_TRUE) {         printf("Failed to compile vertex shader.");         return;     }       glShaderSource(shaderProgram->fragmentShader, 1, &fragSrc, NULL);     glCompileShader(shaderProgram->fragmentShader);     glGetShaderiv(shaderProgram->fragmentShader, GL_COMPILE_STATUS, &err);       if (err != GL_TRUE) {         printf("Failed to compile fragment shader.");         return;     }       shaderProgram->program = glCreateProgram();     glAttachShader(shaderProgram->program, shaderProgram->vertexShader);     glAttachShader(shaderProgram->program, shaderProgram->fragmentShader);     glLinkProgram(shaderProgram->program);          glGetProgramiv(shaderProgram->program, GL_LINK_STATUS, &err);       if (err != GL_TRUE) {         printf("Failed to link shader.");         return;     } }   void destroyShader(ShaderProgram *shaderProgram) {     glDetachShader(shaderProgram->program, shaderProgram->vertexShader);     glDetachShader(shaderProgram->program, shaderProgram->fragmentShader);       glDeleteShader(shaderProgram->vertexShader);     glDeleteShader(shaderProgram->fragmentShader);       glDeleteProgram(shaderProgram->program); }   GLuint getUniformLocation(const char *name, ShaderProgram *program) {     GLuint result = 0;     result = glGetUniformLocation(program->program, name);       return result; }   void setUniformMatrix(float *matrix, const char *name, ShaderProgram *program) {     GLuint loc = getUniformLocation(name, program);       if (loc == -1) {         printf("Failed to get uniform location in setUniformMatrix.\n");         return;     }       glUniformMatrix4fv(loc, 1, GL_FALSE, matrix); }   /*     General functions */ static int isRunning() {     return g_running && !glfwWindowShouldClose(gl_window); }   static void initializeGLFW(GLFWwindow **window, int width, int height, int *success) {     if (!glfwInit()) {         printf("Failed it inialize GLFW.");         *success = FALSE;        return;     }          glfwWindowHint(GLFW_RESIZABLE, 0);     *window = glfwCreateWindow(width, height, "Alignments", NULL, NULL);          if (!*window) {         printf("Failed to create window.");         glfwTerminate();         *success = FALSE;         return;     }          glfwMakeContextCurrent(*window);       GLenum glewErr = glewInit();     if (glewErr != GLEW_OK) {         printf("Failed to initialize GLEW.");         printf(glewGetErrorString(glewErr));         *success = FALSE;         return;     }       glClearColor(0.f, 0.f, 0.f, 1.f);     glViewport(0, 0, width, height);     *success = TRUE; }   int main(int argc, char **argv) {          int err = FALSE;     initializeGLFW(&gl_window, 480, 320, &err);     glDisable(GL_DEPTH_TEST);     if (err == FALSE) {         return 1;     }          createOrthoProjection(gl_projectionMatrix, 480.f, 320.f, 0.f, 1.f);          g_running = TRUE;          ShaderProgram shader;     compileShader(&shader, VERT_SHADER, FRAG_SHADER);     glUseProgram(shader.program);     setUniformMatrix(&gl_projectionMatrix, "uProjectionMatrix", &shader);       Vertex rectangle[6];     VertexBuffer vbo;     rectangle[0] = (Vertex){0.f, 0.f, 0.f, 1.f, 0.f, 0.f}; // Top left     rectangle[1] = (Vertex){3.f, 0.f, 0.f, 1.f, 1.f, 0.f}; // Top right     rectangle[2] = (Vertex){0.f, 3.f, 0.f, 1.f, 0.f, 1.f}; // Bottom left     rectangle[3] = (Vertex){3.f, 0.f, 0.f, 1.f, 1.f, 0.f}; // Top left     rectangle[4] = (Vertex){0.f, 3.f, 0.f, 1.f, 0.f, 1.f}; // Bottom left     rectangle[5] = (Vertex){3.f, 3.f, 0.f, 1.f, 1.f, 1.f}; // Bottom right       createVertexBuffer(&vbo, &rectangle);            bindVertexBuffer(&vbo);          while (isRunning()) {         glClear(GL_COLOR_BUFFER_BIT);         glfwPollEvents();                    drawVertexBuffer();                    glfwSwapBuffers(gl_window);     }          unbindVertexBuffer(&vbo);       glUseProgram(0);     destroyShader(&shader);     destroyVertexBuffer(&vbo);     glfwTerminate();     return 0; }

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  • OpenGL Tessellation makes point

    - by urza57
    A little problem with my tessellation shader. I try to implement a simple tessellation shader but it only makes points. Here's my vertex shader : out vec4 ecPosition; out vec3 ecNormal; void main( void ) { vec4 position = gl_Vertex; gl_Position = gl_ModelViewProjectionMatrix * position; ecPosition = gl_ModelViewMatrix * position; ecNormal = normalize(gl_NormalMatrix * gl_Normal); } My tessellation control shader : layout(vertices = 3) out; out vec4 ecPosition3[]; in vec3 ecNormal[]; in vec4 ecPosition[]; out vec3 myNormal[]; void main() { gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position; myNormal[gl_InvocationID] = ecNormal[gl_InvocationID]; ecPosition3[gl_InvocationID] = ecPosition[gl_InvocationID]; gl_TessLevelOuter[0] = float(4.0); gl_TessLevelOuter[1] = float(4.0); gl_TessLevelOuter[2] = float(4.0); gl_TessLevelInner[0] = float(4.0); } And my Tessellation Evaluation shader: layout(triangles, equal_spacing, ccw) in; in vec3 myNormal[]; in vec4 ecPosition3[]; out vec3 ecNormal; out vec4 ecPosition; void main() { float u = gl_TessCoord.x; float v = gl_TessCoord.y; float w = gl_TessCoord.z; vec3 position = vec4(gl_in[0].gl_Position.xyz * u + gl_in[1].gl_Position.xyz * v + gl_in[2].gl_Position.xyz * w ); vec3 position2 = vec4(ecPosition3[0].xyz * u + ecPosition3[1].xyz * v + ecPosition3[2].xyz * w ); vec3 normal = myNormal[0] * u + myNormal[1] * v + myNormal[2] * w ); ecNormal = normal; gl_Position = vec4(position, 1.0); ecPosition = vec4(position2, 1.0); } Thank you !

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  • The practical cost of swapping effects

    - by sebf
    I use XNA for my projects and on those forums I sometimes see references to the fact that swapping an effect for a mesh has a relatively high cost, which surprises me as I thought to swap an effect was simply a case of copying the replacement shader program to the GPU along with appropriate parameters. I wondered if someone could explain exactly what is costly about this process? And put, if possible, 'relatively' into context? For example say I wanted to use a short shader to help with picking, I would: Change the effect on every object, calculting a unique color to identify it and providing it to the shader. Draw all the objects to a render target in memory. Get the color from the target and use it to look up the selected object. What portion of the total time taken to complete that process would be spent swapping the shaders? My instincts would say that rendering the scene again, no matter how simple the shader, would be an order of magnitude slower than any other part of the process so why all the concern over effects?

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