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/* FDF shader for sampling of rendered silhouette at provided random
* sampling positions in order to update background dot distribution.
*
* (c) 2008 by Mario Kleiner, licensed under MIT license.
*/
#extension GL_ARB_texture_rectangle : enable
uniform sampler2DRect SilSamplePositions;
uniform sampler2DRect Silhouette;
uniform float ViewportHeight;
uniform float SilAcceptThreshold;
void main(void)
{
/* Read sample position from random textures RG channels */
/* Read accept random value from B channel: */
vec3 pos = texture2DRect(SilSamplePositions, gl_TexCoord[0].st).rgb;
/* Sample location from background? Check Silhouette buffer: */
if (pos.z * texture2DRect(Silhouette, pos.xy).b <= SilAcceptThreshold) {
/* Background pixel hit: Emit background vertex. */
gl_FragColor = vec4(pos.x, ViewportHeight - pos.y, 0.5, 1.0);
}
else {
/* Shape pixel hit: Discard vertex: */
gl_FragColor = vec4(0.0, 0.0, -10, 1.0);
}
}
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