From e9747e9d85336baa56c12f664aa0dcda54ee2e6b Mon Sep 17 00:00:00 2001
From: Olivier Prat <olivier@zvork.fr>
Date: Fri, 2 Feb 2018 15:06:22 +0100
Subject: [PATCH] Small optimisations in shadow shader

---
 libraries/render-utils/src/RenderShadowTask.cpp | 4 ++--
 libraries/render-utils/src/RenderShadowTask.h   | 8 ++++----
 libraries/render-utils/src/Shadow.slh           | 2 +-
 libraries/render-utils/src/ShadowCore.slh       | 4 ++--
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/libraries/render-utils/src/RenderShadowTask.cpp b/libraries/render-utils/src/RenderShadowTask.cpp
index 829c0fbcf2..f3797edc11 100644
--- a/libraries/render-utils/src/RenderShadowTask.cpp
+++ b/libraries/render-utils/src/RenderShadowTask.cpp
@@ -380,8 +380,8 @@ void RenderShadowCascadeSetup::run(const render::RenderContextPointer& renderCon
         auto& cascadeFrustum = cascade.getFrustum();
         args->pushViewFrustum(*cascadeFrustum);
         auto texelSize = glm::min(cascadeFrustum->getHeight(), cascadeFrustum->getWidth()) / cascade.framebuffer->getSize().x;
-        // Set the cull threshold to 16 shadow texels.
-        const auto minTexelCount = 16.0f;
+        // Set the cull threshold to 24 shadow texels. This is totally arbitrary
+        const auto minTexelCount = 24.0f;
         // TODO : maybe adapt that with LOD management system?
         texelSize *= minTexelCount;
         _cullFunctor._minSquareSize = texelSize * texelSize;
diff --git a/libraries/render-utils/src/RenderShadowTask.h b/libraries/render-utils/src/RenderShadowTask.h
index 975f755a48..87d78ffe51 100644
--- a/libraries/render-utils/src/RenderShadowTask.h
+++ b/libraries/render-utils/src/RenderShadowTask.h
@@ -82,12 +82,12 @@ public:
 
     float constantBias0{ 0.15f };
     float constantBias1{ 0.15f };
-    float constantBias2{ 0.15f };
-    float constantBias3{ 0.15f };
+    float constantBias2{ 0.175f };
+    float constantBias3{ 0.2f };
     float slopeBias0{ 0.6f };
     float slopeBias1{ 0.6f };
-    float slopeBias2{ 0.6f };
-    float slopeBias3{ 0.6f };
+    float slopeBias2{ 0.7f };
+    float slopeBias3{ 0.82f };
 
 signals:
     void dirty();
diff --git a/libraries/render-utils/src/Shadow.slh b/libraries/render-utils/src/Shadow.slh
index e87519b5f4..abb04a4498 100644
--- a/libraries/render-utils/src/Shadow.slh
+++ b/libraries/render-utils/src/Shadow.slh
@@ -89,7 +89,7 @@ float evalShadowCascadeAttenuation(int cascadeIndex, ShadowSampleOffsets offsets
 
 float evalShadowAttenuation(vec3 worldLightDir, vec4 worldPosition, float viewDepth, vec3 worldNormal) {
     ShadowSampleOffsets offsets = evalShadowFilterOffsets(worldPosition);
-    vec4 cascadeShadowCoords[2];
+    vec4 cascadeShadowCoords[2] = { vec4(0), vec4(0) };
     ivec2 cascadeIndices;
     float cascadeMix = determineShadowCascadesOnPixel(worldPosition, viewDepth, cascadeShadowCoords, cascadeIndices);
 	
diff --git a/libraries/render-utils/src/ShadowCore.slh b/libraries/render-utils/src/ShadowCore.slh
index e49e8d638f..a787c54ca0 100644
--- a/libraries/render-utils/src/ShadowCore.slh
+++ b/libraries/render-utils/src/ShadowCore.slh
@@ -82,10 +82,10 @@ float evalShadowCascadeWeight(vec4 cascadeTexCoords) {
 float determineShadowCascadesOnPixel(vec4 worldPosition, float viewDepth, out vec4 cascadeShadowCoords[2], out ivec2 cascadeIndices) {
     cascadeIndices.x = getFirstShadowCascadeOnPixel(0, worldPosition, cascadeShadowCoords[0]);
     cascadeIndices.y = cascadeIndices.x+1;
-    if (cascadeIndices.x < (getShadowCascadeCount()-1)) {
+    float firstCascadeWeight = evalShadowCascadeWeight(cascadeShadowCoords[0]);
+    if (firstCascadeWeight<1.0 && cascadeIndices.x < (getShadowCascadeCount()-1)) {
         cascadeIndices.y = getFirstShadowCascadeOnPixel(cascadeIndices.y, worldPosition, cascadeShadowCoords[1]);
 
-        float firstCascadeWeight = evalShadowCascadeWeight(cascadeShadowCoords[0]);
         float secondCascadeWeight = evalShadowCascadeWeight(cascadeShadowCoords[1]);
         // Returns the mix amount between first and second cascade.
         return ((1.0-firstCascadeWeight) * secondCascadeWeight) / (firstCascadeWeight + secondCascadeWeight);