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uniform sampler2D tex;
uniform float sigma;
uniform int dir;
uniform float brightness;
uniform float width;
uniform float height;
vec4 getTexture(vec2 uv) {
if (uv.x < 3. / width)
uv.x = 3. / width;
if (uv.y < 3. / height)
uv.y = 3. / height;
if (uv.x > 1. - 3. / width)
uv.x = 1. - 3. / width;
if (uv.y > 1. - 3. / height)
uv.y = 1. - 3. / height;
return texture2D(tex, uv);
}
void main(void) {
vec2 uv = cogl_tex_coord_in[0].xy;
vec2 direction = vec2(dir, (1.0 - dir));
float pixel_step;
if (dir == 0)
pixel_step = 1.0 / height;
else
pixel_step = 1.0 / width;
vec3 gauss_coefficient;
gauss_coefficient.x = 1.0 / (sqrt(2.0 * 3.14159265) * sigma);
gauss_coefficient.y = exp(-0.5 / (sigma * sigma));
gauss_coefficient.z = gauss_coefficient.y * gauss_coefficient.y;
float gauss_coefficient_total = gauss_coefficient.x;
vec4 ret = getTexture(uv) * gauss_coefficient.x;
gauss_coefficient.xy *= gauss_coefficient.yz;
int n_steps = int(ceil(1.5 * sigma)) * 2;
for (int i = 1; i <= n_steps; i += 2) {
float coefficient_subtotal = gauss_coefficient.x;
gauss_coefficient.xy *= gauss_coefficient.yz;
coefficient_subtotal += gauss_coefficient.x;
float gauss_ratio = gauss_coefficient.x / coefficient_subtotal;
float foffset = float(i) + gauss_ratio;
vec2 offset = direction * foffset * pixel_step;
ret += getTexture(uv + offset) * coefficient_subtotal;
ret += getTexture(uv - offset) * coefficient_subtotal;
gauss_coefficient_total += 2.0 * coefficient_subtotal;
gauss_coefficient.xy *= gauss_coefficient.yz;
}
vec4 outColor = ret / gauss_coefficient_total;
// apply brightness on the second pass (dir==0 comes last)
if (dir == 0) {
outColor.rgb *= brightness;
}
cogl_color_out = outColor;
}
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