vertex-shader

I really do not understand how fragment shader works. I know that vertex shader runs once per vertices fragment shader runs once per fragment Since fragment shader does not work per vertex but per fragment how can it send data to the fragment shader? The amount of vertices and amount of fragments are not equal. How can it decide which fragment belong to which vertex? To make sense of this, you'll need to consider the whole render pipeline. The outputs of the vertex shader (besides the special output gl_Position ) is passed along as "associated data" of the vertex to the next stages in the

I'm trying to implement a navigation technique for 3D scenes (in OpenSceneGraph with OpenGL). Among other things the user should be able to click on an scene object on the screen to move towards it. The navigation technique should be integrated into another project which uses a vertex shader to apply a global deformation to the scene geometry. And here is the problem: Since the geometry is deformed using a vertex shader, it is not straight forward to un-project the mouse cursor position to the world coordinates of the spot the user actually selected. But I need those coordinates to perform the

Can anyone provide me the shader that are similar to the Fixed function Pipeline? I need the Fragment shader default the most, because I found a similar vertex shader online. But if you have a pair that should be fine! I want to use fixed pipeline, but have the flexability of shaders, so I need similar shaders so I'll be able to mimic the functionality of the fixed pipeline. Thank you very much! I'm new here so if you need more information tell me:D This is what I would like to replicate: (texture unit 0) functionality of glTranslatef functionality of glColor4f functionality of glTexCoord2f

Given a vertex shader that looks something like #version 400 compatibility const int max_valence = 6; in int valence; in vec3 patch_data[1 + 2 * max_valence]; ... What is the the proper way to map the data to the correct vertex attribs? I'm trying to use a VBO, but I can't figure out how to pass that large of a value in. glVertexAttribPointer takes at most a vector of size 4. What's the correct way to get the vertex attributes into the shader? Arrays of vertex attributes are legal in OpenGL. However, each member of the array takes up a separate attribute index. They are allocated contiguously,

I asked for help about an OpenGL ES 2.0 Problem in this question . What seems to be the answer is very odd to me. Therefore I decided to ask this question in hope of being able to understand what is going on. Here is the piece of faulty vertex-shader code: // a bunch of uniforms and stuff... uniform int u_lights_active; void main() { // some code... for ( int i = 0; i < u_lights_active; ++i ) { // do some stuff using u_lights_active } // some other code... } I know this looks odd but this is really all code that is needed to explain the problem / faulty behavior. My question is: Why is the

I'm trying to create a grid of points by calculating vertex positions dynamically, based on their index in the array of vertices sent to the shader. Is there an equivalent of the gl_VertexID variable that I can call from within my shader? Or another way of accessing their position in the array without having to send more data to the GPU? Thank, Josh. Here's my vertex shader: attribute vec4 vertexPosition; uniform mat4 modelViewProjectionMatrix; vec4 temp; uniform float width; void main() { temp = vertexPosition; // Calculate x and y values based on index: temp.y = floor(gl_VertexID/width);