glsl

I am writing a GLSL shader that simulates chromatic aberration for simple objects. I am staying OpenGL 2.0 compatible, so I use the built-in OpenGL matrix stack. This is the simple vertex shader: uniform vec3 cameraPos; varying vec3 incident; varying vec3 normal; void main(void) { vec4 position = gl_ModelViewMatrix * gl_Vertex; incident = position.xyz / position.w - cameraPos; normal = gl_NormalMatrix * gl_Normal; gl_Position = ftransform(); } The cameraPos uniform is the position of the camera in model space, as one might imagine. Here is the fragment shader: const float etaR = 1.14; const

I want to achieve this effect in my Spritekit game where there is a smooth trail behind the character. See the trail behind the coin in jetpack joyride: And this trail behind the hero in Jupiter Jump: Or this super smooth trail behind the hero in Ski Safari: This appears to be a standard feature in other game engines maybe? I think a spritekit particle emitter will only provide a blocky/stamped trail, not a smooth trail. Should I be using some kind of sprite custom shader? Any other inventive thoughts? Your question did not include a key issue which is the type of movement to be used. My

I read the khronos wiki on this But I don;t really understand what it is saying. What exactly does textureGrad do? I think it samples multiple mipmap levels and computes some color mixing using the explicit derivative vectors given to it. But I am not sure. derhass When you sample a texture, you need the specific texture coordinates to sample the texture data at. For sake of simplicity, I'm going to assume a 2D texture, so the texture coordinates are a 2D vector (s,t) . (The explanation is analogous for other dimensionalities). If you want to texture-map a triangle, one typically uses one of

I need gl_FragColor to "paint" floating point values, which also can be negative (x < 0) and > 1.0. I then want to use the color attachement of the FBO this values where rendered to and use it as a texture in another FBO. Now I have read on http://www.khronos.org/opengles/sdk/docs/man/ (under glTexImage2D) that all values are clamped to a range of [0, 1] and also I didn't find a glClampColor instruction. Is there a possibility to find a workaround here or does somebody have an idea which could help me with my problem? :) SOLVED It is possible and the values are not clamped to [0, 1] at all,

Short: Can I define a function that every shader can use? Or I have to define it per shader? The whole story: I want to create numerous shaders intended to colorize the input fragments with predefined gradient ramps (something like this - http://www.thinkboxsoftware.com/storage/krakatoa-support-images/krakatoa15_kcm_densitybyage_gradientrampmap.png ). I want to define a gradient ramp constant for each shader (an array of vec4 color samples, where the alpha value holds the gradient position, see Pos in the picture above) And I need a function that can return a color sample from the given