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#pragma BLENDER_REQUIRE(gpu_shader_compositor_blur_common.glsl)
#pragma BLENDER_REQUIRE(gpu_shader_compositor_texture_utilities.glsl)
vec4 load_input(ivec2 texel)
{
vec4 color;
if (extend_bounds) {
/* If bounds are extended, then we treat the input as padded by a radius amount of pixels. So
* we load the input with an offset by the radius amount and fallback to a transparent color if
* it is out of bounds. Notice that we subtract 1 because the weights texture have an extra
* center weight, see the SymmetricBlurWeights for more information. */
ivec2 blur_size = texture_size(weights_tx) - 1;
color = texture_load(input_tx, texel - blur_size, vec4(0.0));
}
else {
color = texture_load(input_tx, texel);
}
if (gamma_correct) {
color = gamma_correct_blur_input(color);
}
return color;
}
void main()
{
ivec2 texel = ivec2(gl_GlobalInvocationID.xy);
vec4 accumulated_color = vec4(0.0);
/* First, compute the contribution of the center pixel. */
vec4 center_color = load_input(texel);
accumulated_color += center_color * texture_load(weights_tx, ivec2(0)).x;
ivec2 weights_size = texture_size(weights_tx);
/* Then, compute the contributions of the pixels along the x axis of the filter, noting that the
* weights texture only stores the weights for the positive half, but since the filter is
* symmetric, the same weight is used for the negative half and we add both of their
* contributions. */
for (int x = 1; x < weights_size.x; x++) {
float weight = texture_load(weights_tx, ivec2(x, 0)).x;
accumulated_color += load_input(texel + ivec2(x, 0)) * weight;
accumulated_color += load_input(texel + ivec2(-x, 0)) * weight;
}
/* Then, compute the contributions of the pixels along the y axis of the filter, noting that the
* weights texture only stores the weights for the positive half, but since the filter is
* symmetric, the same weight is used for the negative half and we add both of their
* contributions. */
for (int y = 1; y < weights_size.y; y++) {
float weight = texture_load(weights_tx, ivec2(0, y)).x;
accumulated_color += load_input(texel + ivec2(0, y)) * weight;
accumulated_color += load_input(texel + ivec2(0, -y)) * weight;
}
/* Finally, compute the contributions of the pixels in the four quadrants of the filter, noting
* that the weights texture only stores the weights for the upper right quadrant, but since the
* filter is symmetric, the same weight is used for the rest of the quadrants and we add all four
* of their contributions. */
for (int y = 1; y < weights_size.y; y++) {
for (int x = 1; x < weights_size.x; x++) {
float weight = texture_load(weights_tx, ivec2(x, y)).x;
accumulated_color += load_input(texel + ivec2(x, y)) * weight;
accumulated_color += load_input(texel + ivec2(-x, y)) * weight;
accumulated_color += load_input(texel + ivec2(x, -y)) * weight;
accumulated_color += load_input(texel + ivec2(-x, -y)) * weight;
}
}
if (gamma_correct) {
accumulated_color = gamma_uncorrect_blur_output(accumulated_color);
}
imageStore(output_img, texel, accumulated_color);
}
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