root/OpenSceneGraph-Data/trunk/shaders/stereomatch_aggregate.frag

/* -*- Mode: C -*- */
uniform sampler2DRect textureDiff0;
uniform sampler2DRect textureDiff1;
uniform sampler2DRect textureDiff2;
uniform sampler2DRect textureDiff3;
uniform sampler2DRect textureAggIn;
uniform int start_disparity;
uniform int window_size;

void main(void)
{
    int half_window_size = window_size/2;

    vec2 texCoord = gl_TexCoord[0].xy;
    sampler2DRect tdiff[4];
    tdiff[0] = textureDiff0;
    tdiff[1] = textureDiff1;
    tdiff[2] = textureDiff2;
    tdiff[3] = textureDiff3;
     
    float smallest_sum = 100;
    float sum;
    float disparity = 0;
    
    for (int t=0; t<4; t++) { // four textures
        for (int c=0; c<4; c++) { // four channels
            sum = 0.0;
            for (int y=-half_window_size; y<=half_window_size; y++) {
                for (int x=-half_window_size; x<=half_window_size; x++) {
                    vec2 coord = texCoord + vec2(x,y);
                    vec4 val = texture2DRect(tdiff[t], coord)[c];
                    sum+=val;
                }
            }
            if (sum < smallest_sum) {
                smallest_sum = sum;
                disparity = start_disparity + ((t*4)+c);
            }
        }
    }

    float old_best_sum = texture2DRect(textureAggIn, texCoord)[0];
    float old_disparity = texture2DRect(textureAggIn, texCoord)[1];
    if (smallest_sum < old_best_sum) {
        gl_FragData[0][0] = smallest_sum;
        gl_FragData[0][1] = disparity;
    } else {
        gl_FragData[0][0] = old_best_sum;
        gl_FragData[0][1] = old_disparity;
    }
}