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varying vec2 v_texcoord;
uniform sampler2D tex;
uniform vec2 pixelsize;
/* The rect to match against */
uniform vec4 srect;
uniform int barrier;
void
main()
{
int diff = 0;
float i, j;
for (i = 0.0; i < srect[2] && diff < barrier; i += pixelsize.x) {
for (j = 0.0; j < srect[3] && diff < barrier; j += pixelsize.y) {
vec4 match = texture2D(tex, srect.xy + vec2(i,j));
vec4 orig = texture2D(tex, v_texcoord + vec2(i,j));
diff += int(any(greaterThan(abs(orig - match), vec4(0.2))));
}
}
gl_FragColor = vec4(float(diff < barrier), 0.0, 0.0, 1.0);
}
// vim:ft=c:
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