source: trunk/src/testing/shader/blockGeneration.frag @ 4

// Generating RLE Sequence for RLE compression
// 
// author : Byungil Jeong
//

uniform sampler2D colorMap;
uniform vec2            winSize;
uniform vec2            blockSize;
uniform float           blockPixels;
uniform vec2            blockDim;

void main(void)
{
   const vec2 offset = vec2(1.0 / winSize.x, 1.0/winSize.y);
        const vec4 zeroColor = vec4(0.0);
        
   vec2 texCoord = gl_TexCoord[0].xy;
        vec2 pixelCoord = floor(texCoord*winSize);
        float pixelIdx = pixelCoord.y * winSize.x + pixelCoord.x;
        float blockIdx = floor(pixelIdx/blockPixels);
        vec2 blockPos = vec2(mod(blockIdx,blockDim.x), floor(blockIdx/blockDim.x));
        float innerIdx = mod(pixelIdx,blockPixels);
        vec2 innerPos = vec2(mod(innerIdx,blockSize.x), floor(innerIdx/blockSize.x));
        
        vec2 finalPos = blockPos*blockSize + innerPos; 
        vec2 myCoord = texCoord + (finalPos - pixelCoord)*offset;
        vec4 myColor = texture2D(colorMap, myCoord);

        gl_FragColor = myColor;
}