tmaq
/
tornavis
1
0
Fork 0
Code Issues 2 Pull Requests 29 Packages Projects 24 Releases Wiki Activity

Fix: GPU morphological feather erosion differ from CPU 

The GPU implementation of the morphological feather erosion operator is
different from the CPU implementation. This is because the CPU does
erosion by doing dilation sandwiched between two inverse functions. So
this patch fixes the different by following the CPU implementation.
This commit is contained in:
Omar Emara 2024-01-05 14:21:31 +02:00
parent 581f2d3c7d
commit 752e416813
2 changed files with 10 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
source/blender/compositor/realtime_compositor/shaders/compositor_morphological_distance_feather.glsl
View File

@ -24,9 +24,10 @@
* and intertwined with the Gaussian blur implementation as follows. A search window of a radius
* equivalent to the dilate/erode distance is applied on the image to find either the minimum or
* maximum pixel value multiplied by its corresponding falloff value in the window. For dilation,
* we try to find the maximum, and for erosion, we try to find the minimum. Additionally, we also
* save the falloff value where the minimum or maximum was found. The found value will be that of
* the narrow band distance field and the saved falloff value will be used as the mixing factor
* we try to find the maximum, and for erosion, we try to find the minimum. The implementation uses
* an inverse function to find the minimum, specified through the FUNCTION macro. Additionally, we
* also save the falloff value where the minimum or maximum was found. The found value will be that
* of the narrow band distance field and the saved falloff value will be used as the mixing factor
* with the Gaussian blur.
*
* To make sense of the aforementioned algorithm, assume we are dilating a binary image by 5 pixels
@ -59,7 +60,7 @@ void main()
float accumulated_value = 0.0;
/* Compute the contribution of the center pixel to the blur result. */
float center_value = texture_load(input_tx, texel).x;
float center_value = FUNCTION(texture_load(input_tx, texel).x);
accumulated_value += center_value * texture_load(weights_tx, 0).x;
/* Start with the center value as the maximum/minimum distance and reassign to the true maximum
@ -80,7 +81,7 @@ void main()
* needed to evaluated the positive and negative sides as explain above. */
for (int s = -1; s < 2; s += 2) {
/* Compute the contribution of the pixel to the blur result. */
float value = texture_load(input_tx, texel + ivec2(s * i, 0)).x;
float value = FUNCTION(texture_load(input_tx, texel + ivec2(s * i, 0)).x);
accumulated_value += value * weight;
/* The distance is computed such that its highest value is the pixel value itself, so
@ -88,7 +89,7 @@ void main()
float falloff_distance = value * falloff;
/* Find either the maximum or the minimum for the dilate and erode cases respectively. */
if (COMPARE(falloff_distance, limit_distance)) {
if (falloff_distance > limit_distance) {
limit_distance = falloff_distance;
limit_distance_falloff = falloff;
}
@ -102,5 +103,5 @@ void main()
/* Write the value using the transposed texel. See the execute_distance_feather_horizontal_pass
* method for more information on the rational behind this. */
imageStore(output_img, texel.yx, vec4(value));
imageStore(output_img, texel.yx, vec4(FUNCTION(value)));
}

4
source/blender/compositor/realtime_compositor/shaders/infos/compositor_morphological_distance_feather_info.hh
View File

@ -14,10 +14,10 @@ GPU_SHADER_CREATE_INFO(compositor_morphological_distance_feather_shared)
GPU_SHADER_CREATE_INFO(compositor_morphological_distance_feather_dilate)
.additional_info("compositor_morphological_distance_feather_shared")
.define("COMPARE(x, y)", "x > y")
.define("FUNCTION(x)", "x")
.do_static_compilation(true);
GPU_SHADER_CREATE_INFO(compositor_morphological_distance_feather_erode)
.additional_info("compositor_morphological_distance_feather_shared")
.define("COMPARE(x, y)", "x < y")
.define("FUNCTION(x)", "1.0 - x")
.do_static_compilation(true);