vertex-shader

I have a vertex shader (2.0) doing some instancing - each vertex specifies an index into an array. If I have an array like this: float instanceData[100]; The compiler allocates it 100 constant registers. Each constant register is a float4 , so it's allocating 4 times as much space as is needed. I need a way to make it allocate just 25 constant registers and store four values in each of them. Ideally I'd like a method where it still looks like a float[] on both the CPU and GPU (Right now I am calling EffectParamter.SetValue(Single[]) , I'm using XNA). But manually packing and unpacking a float4

I am learning HLSL for DirectX 11, and I was wondering what exactly is the SV_POSITION that is the output for a Vertex Shader, and the input for a Pixel Shader. 1: Is this x,y,z of every pixel on your screen, or of the object? 2: Why is it 4 32bit floats? 3: Do you need this System Variable for the vertex output? Thank you! The vertex shader stage only has one required output: the position of the vertex. This value is then used by the fixed-function rasterizer to compute which pixels are being drawn and invoke the pixel shader for each one. That's what the system value semantic SV_Position

I created an app that uses GLES2.0 on a HTC Desire S. It works on the HTC, but not on an Samung Galaxy tab10.1. The program cannot be linked (GLES20.glGetProgramiv(mProgram, GLES20.GL_LINK_STATUS, linOk,0) gives-1) and glGetError() gives me an error 1282 (Invalid Operation). When I replace this line (in the shader): graph_coord.z = (texture2D(mytexture, graph_coord.xy / 2.0 + 0.5).r); by graph_coord.z = 0.2; it works also on the galaxy tab. My shader looks like this: private final String vertexShaderCode = "attribute vec2 coord2d;" + "varying vec4 graph_coord;" + "uniform mat4 texture

Code demonstrating issue (comment/uncomment out the gl_Position lines in the vertex shader) var scene; var book; var shaderMaterial; var renderer = new THREE.WebGLRenderer({ antialias: true }); renderer.setClearColor(0x000000); document.body.appendChild(renderer.domElement); var camera = new THREE.PerspectiveCamera(55, 1, 0.1, 40000); window.onresize = function () { renderer.setSize(window.innerWidth, window.innerHeight); camera.aspect = window.innerWidth / window.innerHeight; camera.updateProjectionMatrix(); }; window.onresize(); scene = new THREE.Scene(); camera.position.z = 25; camera

I have pass-through vertex and fragment shaders. vertex shader void main(void) { gl_TexCoord[0] = gl_MultiTexCoord0; gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; } fragment shader void main(void) { gl_FragColor = gl_Color; } Those produce empty rendering (black not background color like glClearBuffer does). If I modify the vertex shader to set the gl_FrontColor to gl_Color it does render untouched OpenGl buffer ... with is the expected behavior of pass-through shaders. void main(void) { gl_FrontColor = gl_Color; //Added line gl_TexCoord[0] = gl_MultiTexCoord0; gl_Position = gl

I was wondering if there was a way to tell if a vertex attribute is enabled from within a vertex shader? I know that if the vertex attribute is disabled all the values will be treated as 0.0, so I could do a test like the following: if (attribute == 0) { // Do something different to normal. } else { // Use the attribute. } But this has the obvious problem for the case that the attribute is enabled and the value is just set to 0 (it will be treated as if it's disabled)! The other solution would be to just use a uniform variable that states whether or not to use the attribute, but I wondered if