diff options
Diffstat (limited to 'source/blender/gpu/shaders/compositor/compositor_blur_variable_size.glsl')
-rw-r--r-- | source/blender/gpu/shaders/compositor/compositor_blur_variable_size.glsl | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/source/blender/gpu/shaders/compositor/compositor_blur_variable_size.glsl b/source/blender/gpu/shaders/compositor/compositor_blur_variable_size.glsl new file mode 100644 index 00000000000..9383bbf9825 --- /dev/null +++ b/source/blender/gpu/shaders/compositor/compositor_blur_variable_size.glsl @@ -0,0 +1,71 @@ +#pragma BLENDER_REQUIRE(gpu_shader_common_math_utils.glsl) +#pragma BLENDER_REQUIRE(gpu_shader_compositor_texture_utilities.glsl) + +/* Given the texel in the range [-radius, radius] in both axis, load the appropriate weight from + * the weights texture, where the given texel (0, 0) corresponds the center of weights texture. + * Note that we load the weights texture inverted along both directions to maintain the shape of + * the weights if it was not symmetrical. To understand why inversion makes sense, consider a 1D + * weights texture whose right half is all ones and whose left half is all zeros. Further, consider + * that we are blurring a single white pixel on a black background. When computing the value of a + * pixel that is to the right of the white pixel, the white pixel will be in the left region of the + * search window, and consequently, without inversion, a zero will be sampled from the left side of + * the weights texture and result will be zero. However, what we expect is that pixels to the right + * of the white pixel will be white, that is, they should sample a weight of 1 from the right side + * of the weights texture, hence the need for inversion. */ +vec4 load_weight(ivec2 texel, float radius) +{ + /* The center zero texel is always assigned a unit weight regardless of the corresponding weight + * in the weights texture. That's to guarantee that at last the center pixel will be accumulated + * even if the weights texture is zero at its center. */ + if (texel == ivec2(0)) { + return vec4(1.0); + } + + /* Add the radius to transform the texel into the range [0, radius * 2], with an additional 0.5 + * to sample at the center of the pixels, then divide by the upper bound plus one to transform + * the texel into the normalized range [0, 1] needed to sample the weights sampler. Finally, + * invert the textures coordinates by subtracting from 1 to maintain the shape of the weights as + * mentioned in the function description. */ + return texture(weights_tx, 1.0 - ((texel + vec2(radius + 0.5)) / (radius * 2 + 1))); +} + +void main() +{ + ivec2 texel = ivec2(gl_GlobalInvocationID.xy); + + /* The mask input is treated as a boolean. If it is zero, then no blurring happens for this + * pixel. Otherwise, the pixel is blurred normally and the mask value is irrelevant. */ + float mask = texture_load(mask_tx, texel).x; + if (mask == 0.0) { + imageStore(output_img, texel, texture_load(input_tx, texel)); + return; + } + + float center_size = texture_load(size_tx, texel).x * base_size; + + /* Go over the window of the given search radius and accumulate the colors multiplied by their + * respective weights as well as the weights themselves, but only if both the size of the center + * pixel and the size of the candidate pixel are less than both the x and y distances of the + * candidate pixel. */ + vec4 accumulated_color = vec4(0.0); + vec4 accumulated_weight = vec4(0.0); + for (int y = -search_radius; y <= search_radius; y++) { + for (int x = -search_radius; x <= search_radius; x++) { + float candidate_size = texture_load(size_tx, texel + ivec2(x, y)).x * base_size; + + /* Skip accumulation if either the x or y distances of the candidate pixel are larger than + * either the center or candidate pixel size. Note that the max and min functions here denote + * "either" in the aforementioned description. */ + float size = min(center_size, candidate_size); + if (max(abs(x), abs(y)) > size) { + continue; + } + + vec4 weight = load_weight(ivec2(x, y), size); + accumulated_color += texture_load(input_tx, texel + ivec2(x, y)) * weight; + accumulated_weight += weight; + } + } + + imageStore(output_img, texel, safe_divide(accumulated_color, accumulated_weight)); +} |