Fix a multithreading crash caused by modification of live Geometry

components/shader/shadervisitor.cpp

@@ -318,9 +318,9 @@ namespace Shader
             const ShaderRequirements& reqs = mRequirements.back();
 
             bool useShader = reqs.mShaderRequired || mForceShaders;
-            bool generateTangents = reqs.mTexStageRequiringTangents != -1 && mAllowedToModifyStateSets;
+            bool generateTangents = reqs.mTexStageRequiringTangents != -1;
 
-            if (useShader || generateTangents)
+            if (mAllowedToModifyStateSets && (useShader || generateTangents))
             {
                 osg::ref_ptr<osg::Geometry> sourceGeometry = &geometry;
                 SceneUtil::RigGeometry* rig = dynamic_cast<SceneUtil::RigGeometry*>(&geometry);
@@ -329,8 +329,6 @@ namespace Shader
 
                 bool requiresSetGeometry = false;
 
-                if (mAllowedToModifyStateSets)
-                {
                 // make sure that all UV sets are there
                 for (std::map<int, std::string>::const_iterator it = reqs.mTextures.begin(); it != reqs.mTextures.end(); ++it)
                 {
@@ -340,7 +338,6 @@ namespace Shader
                         requiresSetGeometry = true;
                     }
                 }
-                }
 
                 if (generateTangents)
                 {