// by Jan Eric Kyprianidis <www.kyprianidis.com>
|
#extension GL_EXT_gpu_shader4 : enable
|
uniform sampler2D src;
|
uniform int radius;
|
|
void main (void) {
|
vec2 src_size = vec2(textureSize2D(src, 0));
|
vec2 uv = gl_FragCoord.xy / src_size;
|
float n = float((radius + 1) * (radius + 1));
|
|
vec3 m[4];
|
vec3 s[4];
|
for (int k = 0; k < 4; ++k) {
|
m[k] = vec3(0.0);
|
s[k] = vec3(0.0);
|
}
|
|
for (int j = -radius; j <= 0; ++j) {
|
for (int i = -radius; i <= 0; ++i) {
|
vec3 c = texture2D(src, uv + vec2(i,j) / src_size).rgb;
|
m[0] += c;
|
s[0] += c * c;
|
}
|
}
|
|
for (int j = -radius; j <= 0; ++j) {
|
for (int i = 0; i <= radius; ++i) {
|
vec3 c = texture2D(src, uv + vec2(i,j) / src_size).rgb;
|
m[1] += c;
|
s[1] += c * c;
|
}
|
}
|
|
for (int j = 0; j <= radius; ++j) {
|
for (int i = 0; i <= radius; ++i) {
|
vec3 c = texture2D(src, uv + vec2(i,j) / src_size).rgb;
|
m[2] += c;
|
s[2] += c * c;
|
}
|
}
|
|
for (int j = 0; j <= radius; ++j) {
|
for (int i = -radius; i <= 0; ++i) {
|
vec3 c = texture2D(src, uv + vec2(i,j) / src_size).rgb;
|
m[3] += c;
|
s[3] += c * c;
|
}
|
}
|
|
|
float min_sigma2 = 1e+2;
|
for (int k = 0; k < 4; ++k) {
|
m[k] /= n;
|
s[k] = abs(s[k] / n - m[k] * m[k]);
|
|
float sigma2 = s[k].r + s[k].g + s[k].b;
|
if (sigma2 < min_sigma2) {
|
min_sigma2 = sigma2;
|
gl_FragColor = vec4(m[k], 1.0);
|
}
|
}
|
| } |
