From ce98d7053bc28913551f9188f575c432cb12ece8 Mon Sep 17 00:00:00 2001
From: AnyOldName3 <krizdjali+github@gmail.com>
Date: Wed, 19 Aug 2020 22:55:41 +0100
Subject: [PATCH] Double buffer view-dependent data stateset

---
 components/sceneutil/mwshadowtechnique.cpp | 17 +++++++++--------
 components/sceneutil/mwshadowtechnique.hpp |  6 +++---
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/components/sceneutil/mwshadowtechnique.cpp b/components/sceneutil/mwshadowtechnique.cpp
index 24ec190ba..ae3a29295 100644
--- a/components/sceneutil/mwshadowtechnique.cpp
+++ b/components/sceneutil/mwshadowtechnique.cpp
@@ -749,7 +749,8 @@ MWShadowTechnique::ViewDependentData::ViewDependentData(MWShadowTechnique* vdsm)
     _viewDependentShadowMap(vdsm)
 {
     OSG_INFO<<"ViewDependentData::ViewDependentData()"<<this<<std::endl;
-    _stateset = new osg::StateSet;
+    for (auto& perFrameStateset : _stateset)
+        perFrameStateset = new osg::StateSet;
 }
 
 void MWShadowTechnique::ViewDependentData::releaseGLObjects(osg::State* state) const
@@ -1400,7 +1401,7 @@ void MWShadowTechnique::cull(osgUtil::CullVisitor& cv)
 
     if (numValidShadows>0)
     {
-        decoratorStateGraph->setStateSet(selectStateSetForRenderingShadow(*vdd));
+        decoratorStateGraph->setStateSet(selectStateSetForRenderingShadow(*vdd, cv.getTraversalNumber()));
     }
 
     // OSG_NOTICE<<"End of shadow setup Projection matrix "<<*cv.getProjectionMatrix()<<std::endl;
@@ -2974,17 +2975,17 @@ void MWShadowTechnique::cullShadowCastingScene(osgUtil::CullVisitor* cv, osg::Ca
     return;
 }
 
-osg::StateSet* MWShadowTechnique::selectStateSetForRenderingShadow(ViewDependentData& vdd) const
+osg::StateSet* MWShadowTechnique::selectStateSetForRenderingShadow(ViewDependentData& vdd, unsigned int traversalNumber) const
 {
-    OSG_INFO<<"   selectStateSetForRenderingShadow() "<<vdd.getStateSet()<<std::endl;
+    OSG_INFO<<"   selectStateSetForRenderingShadow() "<<vdd.getStateSet(traversalNumber)<<std::endl;
 
-    osg::ref_ptr<osg::StateSet> stateset = vdd.getStateSet();
+    osg::ref_ptr<osg::StateSet> stateset = vdd.getStateSet(traversalNumber);
 
     std::lock_guard<std::mutex> lock(_accessUniformsAndProgramMutex);
 
-    vdd.getStateSet()->clear();
+    stateset->clear();
 
-    vdd.getStateSet()->setTextureAttributeAndModes(0, _fallbackBaseTexture.get(), osg::StateAttribute::ON);
+    stateset->setTextureAttributeAndModes(0, _fallbackBaseTexture.get(), osg::StateAttribute::ON);
 
     for(Uniforms::const_iterator itr=_uniforms.begin();
         itr!=_uniforms.end();
@@ -3047,7 +3048,7 @@ osg::StateSet* MWShadowTechnique::selectStateSetForRenderingShadow(ViewDependent
         stateset->setTextureMode(sd._textureUnit,GL_TEXTURE_GEN_Q,osg::StateAttribute::ON);
     }
 
-    return vdd.getStateSet();
+    return stateset;
 }
 
 void MWShadowTechnique::resizeGLObjectBuffers(unsigned int /*maxSize*/)
diff --git a/components/sceneutil/mwshadowtechnique.hpp b/components/sceneutil/mwshadowtechnique.hpp
index 2078fc2d6..95f1117c0 100644
--- a/components/sceneutil/mwshadowtechnique.hpp
+++ b/components/sceneutil/mwshadowtechnique.hpp
@@ -192,7 +192,7 @@ namespace SceneUtil {
 
             ShadowDataList& getShadowDataList() { return _shadowDataList; }
 
-            osg::StateSet* getStateSet() { return _stateset.get(); }
+            osg::StateSet* getStateSet(unsigned int traversalNumber) { return _stateset[traversalNumber % 2].get(); }
 
             virtual void releaseGLObjects(osg::State* = 0) const;
 
@@ -201,7 +201,7 @@ namespace SceneUtil {
 
             MWShadowTechnique*          _viewDependentShadowMap;
 
-            osg::ref_ptr<osg::StateSet> _stateset;
+            std::array<osg::ref_ptr<osg::StateSet>, 2> _stateset;
 
             LightDataList               _lightDataList;
             ShadowDataList              _shadowDataList;
@@ -231,7 +231,7 @@ namespace SceneUtil {
 
         virtual void cullShadowCastingScene(osgUtil::CullVisitor* cv, osg::Camera* camera) const;
 
-        virtual osg::StateSet* selectStateSetForRenderingShadow(ViewDependentData& vdd) const;
+        virtual osg::StateSet* selectStateSetForRenderingShadow(ViewDependentData& vdd, unsigned int traversalNumber) const;
 
     protected:
         virtual ~MWShadowTechnique();