From eb723db1c4c51049c7c858b29734627267aab60c Mon Sep 17 00:00:00 2001
From: Alexander Gauggel <agauggel@uni-koblenz.de>
Date: Fri, 25 Jun 2021 11:38:28 +0200
Subject: [PATCH] [#82] Stabilize shadows
---
projects/voxelization/src/ShadowMapping.cpp | 25 +++++++++++++--------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/projects/voxelization/src/ShadowMapping.cpp b/projects/voxelization/src/ShadowMapping.cpp
index 9c81aa09..051d0673 100644
--- a/projects/voxelization/src/ShadowMapping.cpp
+++ b/projects/voxelization/src/ShadowMapping.cpp
@@ -1,6 +1,11 @@
#include "ShadowMapping.hpp"
#include <vkcv/shader/GLSLCompiler.hpp>
+const vk::Format shadowMapFormat = vk::Format::eR32G32B32A32Sfloat;
+const vk::Format shadowMapDepthFormat = vk::Format::eD32Sfloat;
+const uint32_t shadowMapResolution = 2048;
+const vkcv::Multisampling msaa = vkcv::Multisampling::MSAA8X;
+
vkcv::ShaderProgram loadShadowShader() {
vkcv::ShaderProgram shader;
vkcv::shader::GLSLCompiler compiler;
@@ -114,13 +119,20 @@ glm::mat4 computeShadowViewProjectionMatrix(
getMinMaxView(viewFrustumCorners);
getMinMaxView(voxelVolumeCorners);
- glm::vec3 scale = glm::vec3(2) / (maxView - minView);
-
- // rotationaly invariant to avoid swimming when moving camera
- scale = glm::vec3(glm::max(glm::max(scale.x, scale.y), scale.z));
+ // rotationaly invariant to avoid shadow swimming when moving camera
+ // could potentially be wasteful, but guarantees stability, regardless of camera and voxel volume
+ glm::vec3 scale = glm::vec3(1.f / glm::max(far, voxelVolumeExtent));
glm::vec3 offset = -0.5f * (maxView + minView) * scale;
+ // snap to texel to avoid shadow swimming when moving
+ glm::vec2 offset2D = glm::vec2(offset);
+ glm::vec2 frustumExtent2D = glm::vec2(1) / glm::vec2(scale);
+ glm::vec2 texelSize = glm::vec2(frustumExtent2D / static_cast<float>(shadowMapResolution));
+ offset2D = glm::ceil(offset2D / texelSize) * texelSize;
+ offset.x = offset2D.x;
+ offset.y = offset2D.y;
+
glm::mat4 crop(1);
crop[0][0] = scale.x;
crop[1][1] = scale.y;
@@ -137,11 +149,6 @@ glm::mat4 computeShadowViewProjectionMatrix(
return vulkanCorrectionMatrix * crop * view;
}
-const vk::Format shadowMapFormat = vk::Format::eR32G32B32A32Sfloat;
-const vk::Format shadowMapDepthFormat = vk::Format::eD32Sfloat;
-const uint32_t shadowMapResolution = 2048;
-const vkcv::Multisampling msaa = vkcv::Multisampling::MSAA8X;
-
ShadowMapping::ShadowMapping(vkcv::Core* corePtr, const vkcv::VertexLayout& vertexLayout) :
m_corePtr(corePtr),
m_shadowMap(corePtr->createImage(shadowMapFormat, shadowMapResolution, shadowMapResolution, 1, true, true)),
--
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