glsl

I am using three.js to call a fragment shader - that shader specifies a color for my material, broken out into rgb - and I want to see if I can multiply those colors by a random value. This is the code I'm using so far: gl_FragColor = vec4( color.r*.5, color.g, color.b, smoothstep( 8000.0, -8000.0, gl_FragCoord.z / gl_FragCoord.w ) ); //MH - creates colors by multiplying color values and this is what I'd want to do if it were javascript, though obviously this doesn't work inside a GLSL shader script: gl_FragColor = vec4( color.r*Math.random(), color.g, color.b, smoothstep( 8000.0, -8000.0, gl

In short: Can anyone confirm whether it is possible to use the built-in variable gl_InstanceID (or gl_InstanceIDEXT ) in a vertex shader using OpenGL ES 2.0 on iOS with GL_EXT_draw_instanced enabled? Longer: I want to draw multiple instances of an object using glDrawArraysInstanced and gl_InstanceID , and I want my application to run on multiple platforms, including iOS. The specification clearly says that these features require ES 3.0. According to the iOS Device Compatibility Reference ES 3.0 is only available on a few devices (those based on the A7 GPU; so iPhone 5s, but not on iPhone 5 or

In my Mac application, I define a rectangular texture based on YUV 4:2:2 data from an attached camera. Using standard vertex and texture coordinates, I can draw this to a rectangular area on the screen without any problems. However, I would like to use a GLSL fragment shader to process these image frames on the GPU, and am having trouble passing in the rectangular video texture as a uniform to the fragment shader. When I attempt to do so, the texture simply reads as black. The shader program compiles, links, and passes validation. I am receiving the proper address for the uniform from the

I want to repeat wrapping texture in THREE.js shader. The original texture image is: I want it to repeat 4x4 times which will looks like: But with the following code, it turns out to be: Vertex shader: varying vec2 vUv; uniform float textRepeat; void main() { // passing texture to fragment shader vUv = uv * textRepeat; gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0); } Fragment shader: varying vec2 vUv; uniform sampler2D texture; void main() { // add origianl texture gl_FragColor = texture2D(texture, vUv); } uniforms in a JavaScript file, in which textureRepeat gives the

when I switch to use OpenGL ES 3 with GLSL 300, I met the following error in my frag shader undeclared identifier gl_FragColor when using GLSL 100, everything is fine. Modern versions of GLSL do fragment shader outputs simply by declaring them as out values, and gl_FragColor is no longer supported, hence your error. Try this: out vec4 fragColor; void main() { fragColor = vec4(1.0, 0.0, 0.0, 1.0); } Note that gl_FragDepth hasn't changed and is still available. For more information see https://www.opengl.org/wiki/Fragment_Shader The predefined variable gl_FragColor does not exist anymore in GLSL

I'm currently chasing some bugs in my OpenGL ES 2.0 fragment shader code which is running on iOS devices. The code runs fine in the simulator, but on the iPad it has huge problems and some of the calculations yield vastly different results, I had for example 0.0 on the iPad and 4013.17 on the simulator, so I'm not talking about small differences which could be the result of some rounding errors. One of the things I noticed is that, on the iPad, float1 = pow(float2, 2.0); can yield results which are very different from the results of float1 = float2 * float2; Specifically, when using pow(x, 2.0