From 633117669bcec0f5320cb88443d12b6661bc4886 Mon Sep 17 00:00:00 2001 From: Omar Emara Date: Fri, 2 Sep 2022 14:47:39 +0200 Subject: Realtime Compositor: Implement dilate erode node This patch implements the dilate/erode node for the realtime compositor. Differential Revision: https://developer.blender.org/D15790 Reviewed By: Clement Foucault --- .../compositor_morphological_distance.glsl | 24 +++++ .../compositor_morphological_distance_feather.glsl | 101 +++++++++++++++++++++ ...ompositor_morphological_distance_threshold.glsl | 88 ++++++++++++++++++ .../compositor/compositor_morphological_step.glsl | 19 ++++ ...mpositor_morphological_distance_feather_info.hh | 21 +++++ .../compositor_morphological_distance_info.hh | 22 +++++ ...ositor_morphological_distance_threshold_info.hh | 13 +++ .../infos/compositor_morphological_step_info.hh | 22 +++++ .../gpu_shader_compositor_texture_utilities.glsl | 10 ++ 9 files changed, 320 insertions(+) create mode 100644 source/blender/gpu/shaders/compositor/compositor_morphological_distance.glsl create mode 100644 source/blender/gpu/shaders/compositor/compositor_morphological_distance_feather.glsl create mode 100644 source/blender/gpu/shaders/compositor/compositor_morphological_distance_threshold.glsl create mode 100644 source/blender/gpu/shaders/compositor/compositor_morphological_step.glsl create mode 100644 source/blender/gpu/shaders/compositor/infos/compositor_morphological_distance_feather_info.hh create mode 100644 source/blender/gpu/shaders/compositor/infos/compositor_morphological_distance_info.hh create mode 100644 source/blender/gpu/shaders/compositor/infos/compositor_morphological_distance_threshold_info.hh create mode 100644 source/blender/gpu/shaders/compositor/infos/compositor_morphological_step_info.hh (limited to 'source/blender/gpu/shaders') diff --git a/source/blender/gpu/shaders/compositor/compositor_morphological_distance.glsl b/source/blender/gpu/shaders/compositor/compositor_morphological_distance.glsl new file mode 100644 index 00000000000..09f896b7a9d --- /dev/null +++ b/source/blender/gpu/shaders/compositor/compositor_morphological_distance.glsl @@ -0,0 +1,24 @@ +#pragma BLENDER_REQUIRE(common_math_lib.glsl) +#pragma BLENDER_REQUIRE(gpu_shader_compositor_texture_utilities.glsl) + +void main() +{ + ivec2 texel = ivec2(gl_GlobalInvocationID.xy); + + /* Find the minimum/maximum value in the circular window of the given radius around the pixel. By + * circular window, we mean that pixels in the window whose distance to the center of window is + * larger than the given radius are skipped and not considered. Consequently, the dilation or + * erosion that take place produces round results as opposed to squarish ones. This is + * essentially a morphological operator with a circular structuring element. The LIMIT value + * should be FLT_MAX if OPERATOR is min and FLT_MIN if OPERATOR is max. */ + float value = LIMIT; + for (int y = -radius; y <= radius; y++) { + for (int x = -radius; x <= radius; x++) { + if (x * x + y * y <= radius * radius) { + value = OPERATOR(value, texture_load(input_tx, texel + ivec2(x, y), vec4(LIMIT)).x); + } + } + } + + imageStore(output_img, texel, vec4(value)); +} diff --git a/source/blender/gpu/shaders/compositor/compositor_morphological_distance_feather.glsl b/source/blender/gpu/shaders/compositor/compositor_morphological_distance_feather.glsl new file mode 100644 index 00000000000..8034f4a3ebd --- /dev/null +++ b/source/blender/gpu/shaders/compositor/compositor_morphological_distance_feather.glsl @@ -0,0 +1,101 @@ +#pragma BLENDER_REQUIRE(gpu_shader_compositor_texture_utilities.glsl) + +/* The Morphological Distance Feather operation is a linear combination between the result of two + * operations. The first operation is a Gaussian blur with a radius equivalent to the dilate/erode + * distance, which is straightforward and implemented as a separable filter similar to the blur + * operation. + * + * The second operation is an approximation of a morphological inverse distance operation evaluated + * at a distance falloff function. The result of a morphological inverse distance operation is a + * narrow band distance field that starts at its maximum value at boundaries where a difference in + * values took place and linearly deceases until it reaches zero in the span of a number of pixels + * equivalent to the erode/dilate distance. Additionally, instead of linearly decreasing, the user + * may choose a different falloff which is evaluated at the computed distance. For dilation, the + * distance field decreases outwards, and for erosion, the distance field decreased inwards. + * + * The reason why the result of a Gaussian blur is mixed in with the distance field is because the + * distance field is merely approximated and not accurately computed, the defects of which is more + * apparent away from boundaries and especially at corners where the distance field should take a + * circular shape. That's why the Gaussian blur is mostly mixed only further from boundaries. + * + * The morphological inverse distance operation is approximated using a separable implementation + * 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 + * with the Gaussian blur. + * + * To make sense of the aforementioned algorithm, assume we are dilating a binary image by 5 pixels + * whose half has a value of 1 and the other half has a value of zero. Consider the following: + * + * - A pixel of value 1 already has the maximum possible value, so its value will remain unchanged + * regardless of its position. + * - A pixel of value 0 that is right at the boundary of the 1's region will have a maximum value + * of around 0.8 depending on the falloff. That's because the search window intersects the 1's + * region, which when multiplied by the falloff gives the first value of the falloff, which is + * larger than the initially zero value computed at the center of the search window. + * - A pixel of value 0 that is 3 pixels away from the boundary will have a maximum value of around + * 0.4 depending on the falloff. That's because the search window intersects the 1's region, + * which when multiplied by the falloff gives the third value of the falloff, which is larger + * than the initially zero value computed at the center of the search window. + * - Finally, a pixel of value 0 that is 6 pixels away from the boundary will have a maximum value + * of 0, because the search window doesn't intersects the 1's region and only spans zero values. + * + * The previous example demonstrates how the distance field naturally arises, and the same goes for + * the erode case, except the minimum value is computed instead. + */ +void main() +{ + ivec2 texel = ivec2(gl_GlobalInvocationID.xy); + + /* A value for accumulating the blur result. */ + 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; + 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 + * or minimum in the search loop below. Additionally, the center falloff is always 1.0, so start + * with that. */ + float limit_distance = center_value; + float limit_distance_falloff = 1.0; + + /* Compute the contributions of the pixels to the right and left, noting that the weights and + * falloffs textures only store the weights and falloffs for the positive half, but since the + * they are both symmetric, the same weights and falloffs are used for the negative half and we + * compute both of their contributions. */ + for (int i = 1; i < texture_size(weights_tx); i++) { + float weight = texture_load(weights_tx, i).x; + float falloff = texture_load(falloffs_tx, i).x; + + /* Loop for two iterations, where s takes the value of -1 and 1, which is used as the sign + * 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; + accumulated_value += value * weight; + + /* The distance is computed such that its highest value is the pixel value itself, so + * multiply the distance falloff by the pixel value. */ + 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)) { + limit_distance = falloff_distance; + limit_distance_falloff = falloff; + } + } + } + + /* Mix between the limit distance and the blurred accumulated value such that the limit distance + * is used for pixels closer to the boundary and the blurred value is used for pixels away from + * the boundary. */ + float value = mix(accumulated_value, limit_distance, limit_distance_falloff); + + /* 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)); +} diff --git a/source/blender/gpu/shaders/compositor/compositor_morphological_distance_threshold.glsl b/source/blender/gpu/shaders/compositor/compositor_morphological_distance_threshold.glsl new file mode 100644 index 00000000000..5931c4f0271 --- /dev/null +++ b/source/blender/gpu/shaders/compositor/compositor_morphological_distance_threshold.glsl @@ -0,0 +1,88 @@ +#pragma BLENDER_REQUIRE(gpu_shader_compositor_texture_utilities.glsl) + +/* The Morphological Distance Threshold operation is effectively three consecutive operations + * implemented as a single operation. The three operations are as follows: + * + * .-----------. .--------------. .----------------. + * | Threshold |-->| Dilate/Erode |-->| Distance Inset | + * '-----------' '--------------' '----------------' + * + * The threshold operation just converts the input into a binary image, where the pixel is 1 if it + * is larger than 0.5 and 0 otherwise. Pixels that are 1 in the output of the threshold operation + * are said to be masked. The dilate/erode operation is a dilate or erode morphological operation + * with a circular structuring element depending on the sign of the distance, where it is a dilate + * operation if the distance is positive and an erode operation otherwise. This is equivalent to + * the Morphological Distance operation, see its implementation for more information. Finally, the + * distance inset is an operation that converts the binary image into a narrow band distance field. + * That is, pixels that are unmasked will remain 0, while pixels that are masked will start from + * zero at the boundary of the masked region and linearly increase until reaching 1 in the span of + * a number pixels given by the inset value. + * + * As a performance optimization, the dilate/erode operation is omitted and its effective result is + * achieved by slightly adjusting the distance inset operation. The base distance inset operation + * works by computing the signed distance from the current center pixel to the nearest pixel with a + * different value. Since our image is a binary image, that means that if the pixel is masked, we + * compute the signed distance to the nearest unmasked pixel, and if the pixel unmasked, we compute + * the signed distance to the nearest masked pixel. The distance is positive if the pixel is masked + * and negative otherwise. The distance is then normalized by dividing by the given inset value and + * clamped to the [0, 1] range. Since distances larger than the inset value are eventually clamped, + * the distance search window is limited to a radius equivalent to the inset value. + * + * To archive the effective result of the omitted dilate/erode operation, we adjust the distance + * inset operation as follows. First, we increase the radius of the distance search window by the + * radius of the dilate/erode operation. Then we adjust the resulting narrow band signed distance + * field as follows. + * + * For the erode case, we merely subtract the erode distance, which makes the outermost erode + * distance number of pixels zero due to clamping, consequently achieving the result of the erode, + * while retaining the needed inset because we increased the distance search window by the same + * amount we subtracted. + * + * Similarly, for the dilate case, we add the dilate distance, which makes the dilate distance + * number of pixels just outside of the masked region positive and part of the narrow band distance + * field, consequently achieving the result of the dilate, while at the same time, the innermost + * dilate distance number of pixels become 1 due to clamping, retaining the needed inset because we + * increased the distance search window by the same amount we added. + * + * Since the erode/dilate distance is already signed appropriately as described before, we just add + * it in both cases. */ +void main() +{ + ivec2 texel = ivec2(gl_GlobalInvocationID.xy); + + /* Apply a threshold operation on the center pixel, where the threshold is currently hard-coded + * at 0.5. The pixels with values larger than the threshold are said to be masked. */ + bool is_center_masked = texture_load(input_tx, texel).x > 0.5; + + /* Since the distance search window will access pixels outside of the bounds of the image, we use + * a texture loader with a fallback value. And since we don't want those values to affect the + * result, the fallback value is chosen such that the inner condition fails, which is when the + * sampled pixel and the center pixel are the same, so choose a fallback that will be considered + * masked if the center pixel is masked and unmasked otherwise. */ + vec4 fallback = vec4(is_center_masked ? 1.0 : 0.0); + + /* Since the distance search window is limited to the given radius, the maximum possible squared + * distance to the center is double the squared radius. */ + int minimum_squared_distance = radius * radius * 2; + + /* Find the squared distance to the nearest different pixel in the search window of the given + * radius. */ + for (int y = -radius; y <= radius; y++) { + for (int x = -radius; x <= radius; x++) { + bool is_sample_masked = texture_load(input_tx, texel + ivec2(x, y), fallback).x > 0.5; + if (is_center_masked != is_sample_masked) { + minimum_squared_distance = min(minimum_squared_distance, x * x + y * y); + } + } + } + + /* Compute the actual distance from the squared distance and assign it an appropriate sign + * depending on whether it lies in a masked region or not. */ + float signed_minimum_distance = sqrt(minimum_squared_distance) * (is_center_masked ? 1.0 : -1.0); + + /* Add the erode/dilate distance and divide by the inset amount as described in the discussion, + * then clamp to the [0, 1] range. */ + float value = clamp((signed_minimum_distance + distance) / inset, 0.0, 1.0); + + imageStore(output_img, texel, vec4(value)); +} diff --git a/source/blender/gpu/shaders/compositor/compositor_morphological_step.glsl b/source/blender/gpu/shaders/compositor/compositor_morphological_step.glsl new file mode 100644 index 00000000000..6992bc2afa5 --- /dev/null +++ b/source/blender/gpu/shaders/compositor/compositor_morphological_step.glsl @@ -0,0 +1,19 @@ +#pragma BLENDER_REQUIRE(common_math_lib.glsl) +#pragma BLENDER_REQUIRE(gpu_shader_compositor_texture_utilities.glsl) + +void main() +{ + ivec2 texel = ivec2(gl_GlobalInvocationID.xy); + + /* Find the minimum/maximum value in the window of the given radius around the pixel. This is + * essentially a morphological operator with a square structuring element. The LIMIT value should + * be FLT_MAX if OPERATOR is min and FLT_MIN if OPERATOR is max. */ + float value = LIMIT; + for (int i = -radius; i <= radius; i++) { + value = OPERATOR(value, texture_load(input_tx, texel + ivec2(i, 0), vec4(LIMIT)).x); + } + + /* Write the value using the transposed texel. See the execute_step_horizontal_pass method for + * more information on the rational behind this. */ + imageStore(output_img, texel.yx, vec4(value)); +} diff --git a/source/blender/gpu/shaders/compositor/infos/compositor_morphological_distance_feather_info.hh b/source/blender/gpu/shaders/compositor/infos/compositor_morphological_distance_feather_info.hh new file mode 100644 index 00000000000..9f17f60129d --- /dev/null +++ b/source/blender/gpu/shaders/compositor/infos/compositor_morphological_distance_feather_info.hh @@ -0,0 +1,21 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#include "gpu_shader_create_info.hh" + +GPU_SHADER_CREATE_INFO(compositor_morphological_distance_feather_shared) + .local_group_size(16, 16) + .sampler(0, ImageType::FLOAT_2D, "input_tx") + .sampler(1, ImageType::FLOAT_1D, "weights_tx") + .sampler(2, ImageType::FLOAT_1D, "falloffs_tx") + .image(0, GPU_RGBA16F, Qualifier::WRITE, ImageType::FLOAT_2D, "output_img") + .compute_source("compositor_morphological_distance_feather.glsl"); + +GPU_SHADER_CREATE_INFO(compositor_morphological_distance_feather_dilate) + .additional_info("compositor_morphological_distance_feather_shared") + .define("COMPARE(x, y)", "x > y") + .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") + .do_static_compilation(true); diff --git a/source/blender/gpu/shaders/compositor/infos/compositor_morphological_distance_info.hh b/source/blender/gpu/shaders/compositor/infos/compositor_morphological_distance_info.hh new file mode 100644 index 00000000000..fc960e119e5 --- /dev/null +++ b/source/blender/gpu/shaders/compositor/infos/compositor_morphological_distance_info.hh @@ -0,0 +1,22 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#include "gpu_shader_create_info.hh" + +GPU_SHADER_CREATE_INFO(compositor_morphological_distance_shared) + .local_group_size(16, 16) + .push_constant(Type::INT, "radius") + .sampler(0, ImageType::FLOAT_2D, "input_tx") + .image(0, GPU_R16F, Qualifier::WRITE, ImageType::FLOAT_2D, "output_img") + .compute_source("compositor_morphological_distance.glsl"); + +GPU_SHADER_CREATE_INFO(compositor_morphological_distance_dilate) + .additional_info("compositor_morphological_distance_shared") + .define("OPERATOR(a, b)", "max(a, b)") + .define("LIMIT", "FLT_MIN") + .do_static_compilation(true); + +GPU_SHADER_CREATE_INFO(compositor_morphological_distance_erode) + .additional_info("compositor_morphological_distance_shared") + .define("OPERATOR(a, b)", "min(a, b)") + .define("LIMIT", "FLT_MAX") + .do_static_compilation(true); diff --git a/source/blender/gpu/shaders/compositor/infos/compositor_morphological_distance_threshold_info.hh b/source/blender/gpu/shaders/compositor/infos/compositor_morphological_distance_threshold_info.hh new file mode 100644 index 00000000000..b1d64f61b80 --- /dev/null +++ b/source/blender/gpu/shaders/compositor/infos/compositor_morphological_distance_threshold_info.hh @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#include "gpu_shader_create_info.hh" + +GPU_SHADER_CREATE_INFO(compositor_morphological_distance_threshold) + .local_group_size(16, 16) + .push_constant(Type::INT, "radius") + .push_constant(Type::INT, "distance") + .push_constant(Type::FLOAT, "inset") + .sampler(0, ImageType::FLOAT_2D, "input_tx") + .image(0, GPU_R16F, Qualifier::WRITE, ImageType::FLOAT_2D, "output_img") + .compute_source("compositor_morphological_distance_threshold.glsl") + .do_static_compilation(true); diff --git a/source/blender/gpu/shaders/compositor/infos/compositor_morphological_step_info.hh b/source/blender/gpu/shaders/compositor/infos/compositor_morphological_step_info.hh new file mode 100644 index 00000000000..e97ffd9feea --- /dev/null +++ b/source/blender/gpu/shaders/compositor/infos/compositor_morphological_step_info.hh @@ -0,0 +1,22 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#include "gpu_shader_create_info.hh" + +GPU_SHADER_CREATE_INFO(compositor_morphological_step_shared) + .local_group_size(16, 16) + .push_constant(Type::INT, "radius") + .sampler(0, ImageType::FLOAT_2D, "input_tx") + .image(0, GPU_R16F, Qualifier::WRITE, ImageType::FLOAT_2D, "output_img") + .compute_source("compositor_morphological_step.glsl"); + +GPU_SHADER_CREATE_INFO(compositor_morphological_step_dilate) + .additional_info("compositor_morphological_step_shared") + .define("OPERATOR(a, b)", "max(a, b)") + .define("LIMIT", "FLT_MIN") + .do_static_compilation(true); + +GPU_SHADER_CREATE_INFO(compositor_morphological_step_erode) + .additional_info("compositor_morphological_step_shared") + .define("OPERATOR(a, b)", "min(a, b)") + .define("LIMIT", "FLT_MAX") + .do_static_compilation(true); diff --git a/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_texture_utilities.glsl b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_texture_utilities.glsl index 00e9a391097..128fc6aeaf5 100644 --- a/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_texture_utilities.glsl +++ b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_texture_utilities.glsl @@ -23,3 +23,13 @@ vec4 texture_load(sampler2D sampler, ivec2 texel) const ivec2 texture_bounds = texture_size(sampler) - ivec2(1); return texelFetch(sampler, clamp(texel, ivec2(0), texture_bounds), 0); } + +/* A shorthand for 2D texelFetch with zero LOD and a fallback value for out-of-bound access. */ +vec4 texture_load(sampler2D sampler, ivec2 texel, vec4 fallback) +{ + const ivec2 texture_bounds = texture_size(sampler) - ivec2(1); + if (any(lessThan(texel, ivec2(0))) || any(greaterThan(texel, texture_bounds))) { + return fallback; + } + return texelFetch(sampler, texel, 0); +} -- cgit v1.2.3