From f04fcfcd45ac49dbb62a333d068938ab7c479ad6 Mon Sep 17 00:00:00 2001
From: Alexander Gauggel <agauggel@uni-koblenz.de>
Date: Thu, 24 Jun 2021 19:47:45 +0200
Subject: [PATCH] [#82] Add alpha to coverage to anti-alias alpha tested
geometry
---
include/vkcv/PipelineConfig.hpp | 3 ++-
.../resources/shaders/depthPrepass.frag | 14 ++++++++++----
projects/voxelization/src/main.cpp | 7 ++++---
src/vkcv/PipelineManager.cpp | 2 +-
4 files changed, 17 insertions(+), 9 deletions(-)
diff --git a/include/vkcv/PipelineConfig.hpp b/include/vkcv/PipelineConfig.hpp
index 0d29625a..b1dd56d5 100644
--- a/include/vkcv/PipelineConfig.hpp
+++ b/include/vkcv/PipelineConfig.hpp
@@ -32,7 +32,8 @@ namespace vkcv {
Multisampling m_multisampling = Multisampling::None;
CullMode m_culling = CullMode::None;
DepthTest m_depthTest = DepthTest::LessEqual;
- bool m_depthWrite = true;
+ bool m_depthWrite = true;
+ bool m_alphaToCoverage = false;
};
}
\ No newline at end of file
diff --git a/projects/voxelization/resources/shaders/depthPrepass.frag b/projects/voxelization/resources/shaders/depthPrepass.frag
index b2401639..5e2f7a09 100644
--- a/projects/voxelization/resources/shaders/depthPrepass.frag
+++ b/projects/voxelization/resources/shaders/depthPrepass.frag
@@ -6,9 +6,15 @@
layout(location = 0) in vec2 passUV;
+layout(location = 0) out vec4 outColor; // only used for alpha to coverage, not actually written to
+
+// coverage to alpha techniques explained in: https://bgolus.medium.com/anti-aliased-alpha-test-the-esoteric-alpha-to-coverage-8b177335ae4f
void main() {
- float alpha = texture(sampler2D(albedoTexture, textureSampler), passUV).a;
- if(alpha < 0.5){
- discard;
- }
+ float alpha = texture(sampler2D(albedoTexture, textureSampler), passUV).a;
+ float alphaCutoff = 0.5;
+
+ // scale alpha to one pixel width
+ alpha = (alpha - alphaCutoff) / max(fwidth(alpha), 0.0001) + 0.5;
+
+ outColor.a = alpha;
}
\ No newline at end of file
diff --git a/projects/voxelization/src/main.cpp b/projects/voxelization/src/main.cpp
index c3ca1c7f..d2b1ca56 100644
--- a/projects/voxelization/src/main.cpp
+++ b/projects/voxelization/src/main.cpp
@@ -263,9 +263,10 @@ int main(int argc, const char** argv) {
core.getDescriptorSet(prepassDescriptorSet).layout,
core.getDescriptorSet(perMeshDescriptorSets[0]).layout },
true };
- prepassPipelineConfig.m_culling = vkcv::CullMode::Back;
- prepassPipelineConfig.m_multisampling = msaa;
- prepassPipelineConfig.m_depthTest = vkcv::DepthTest::LessEqual;
+ prepassPipelineConfig.m_culling = vkcv::CullMode::Back;
+ prepassPipelineConfig.m_multisampling = msaa;
+ prepassPipelineConfig.m_depthTest = vkcv::DepthTest::LessEqual;
+ prepassPipelineConfig.m_alphaToCoverage = true;
vkcv::PipelineHandle prepassPipeline = core.createGraphicsPipeline(prepassPipelineConfig);
diff --git a/src/vkcv/PipelineManager.cpp b/src/vkcv/PipelineManager.cpp
index ca0f9225..212e5b56 100644
--- a/src/vkcv/PipelineManager.cpp
+++ b/src/vkcv/PipelineManager.cpp
@@ -193,7 +193,7 @@ namespace vkcv
false,
0.f,
nullptr,
- false,
+ config.m_alphaToCoverage,
false
);
--
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