/* FDF shader for sampling of rendered silhouette at provided random
 * sampling positions in order to update sample distribution.
 *
 * (c) 2008 by Mario Kleiner, licensed under MIT license.
 */

#extension GL_ARB_texture_rectangle : enable


uniform sampler2DRect SilSamplePositions;
uniform sampler2DRect Silhouette;

uniform vec4 TextureOffsetBias;

void main(void)
{
    /* Read sample position from random textures RA channels */
    vec2 pos = texture2DRect(SilSamplePositions, gl_TexCoord[0].st).ra;

    /* Readout sample location from Silhouette - Writeout to sampleBuffer: */
    gl_FragColor = texture2DRect(Silhouette, pos);

    /* Need to remap texture coordinate range to available range in trackingBuffer: */
    gl_FragColor.xy = (gl_FragColor.xy - TextureOffsetBias.xy) * TextureOffsetBias.zw;
}