From 488b4854b2b866b317482a29a13bb5722f90f892 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Mon, 21 Jan 2019 17:36:40 +0000
Subject: [PATCH] Added reset of the State::CurrentVertexArrayState() to
 prevent the State::_vas becoming a dangling pointer when VertexArrayState
 objects are deleted.

---
 include/osg/State            |  3 +++
 include/osg/VertexArrayState |  2 ++
 src/osg/VertexArrayState.cpp | 13 +++++++++++--
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/include/osg/State b/include/osg/State
index d795ae88a..d003e6bb9 100644
--- a/include/osg/State
+++ b/include/osg/State
@@ -549,6 +549,9 @@ class OSG_EXPORT State : public Referenced
         /** Set the getCurrentVertexArrayState to the GlobalVertexArrayState.*/
         void setCurrentToGlobalVertexArrayState() { _vas = _globalVertexArrayState.get(); }
 
+        /** Reset the CurrentVertexArrayObject if it's value equals the specificied vas - use when deleting a vas.*/
+        void resetCurrentVertexArrayStateOnMatch(VertexArrayState* vas) { if (_vas==vas) _vas = 0; }
+
 
         /** disable the vertex, normal, color, tex coords, secondary color, fog coord and index arrays.*/
         void disableAllVertexArrays();
diff --git a/include/osg/VertexArrayState b/include/osg/VertexArrayState
index 5b66db4a9..ef717719b 100644
--- a/include/osg/VertexArrayState
+++ b/include/osg/VertexArrayState
@@ -182,10 +182,12 @@ class OSG_EXPORT VertexArrayState : public osg::Referenced
 
     public:
 
+        virtual ~VertexArrayState();
 
         // osg::GLBufferObject* getGLBufferObject(osg::Array* array);
 
         osg::State*                     _state;
+        osg::ref_ptr<ObserverSet>       _stateObserverSet;
         osg::ref_ptr<osg::GLExtensions> _ext;
 
         bool                            _isVertexBufferObjectSupported;
diff --git a/src/osg/VertexArrayState.cpp b/src/osg/VertexArrayState.cpp
index a644a2e2c..b3c4943d3 100644
--- a/src/osg/VertexArrayState.cpp
+++ b/src/osg/VertexArrayState.cpp
@@ -488,7 +488,7 @@ struct VertexAttribArrayDispatch : public VertexArrayState::ArrayDispatch
     virtual void enable_and_dispatch(osg::State& state, GLint size, GLenum type, GLsizei stride, const GLvoid *ptr, GLboolean normalized)
     {
         GLExtensions* ext = state.get<GLExtensions>();
- 
+
         ext->glEnableVertexAttribArray( unit );
         ext->glVertexAttribPointer(static_cast<GLuint>(unit), size, type, normalized, stride, ptr);
     }
@@ -526,10 +526,19 @@ VertexArrayState::VertexArrayState(osg::State* state):
     _currentEBO(0),
     _requiresSetArrays(true)
 {
+    _stateObserverSet = _state->getOrCreateObserverSet();
     _ext = _state->get<GLExtensions>();
     _isVertexBufferObjectSupported =  _ext->isBufferObjectSupported;
 }
 
+VertexArrayState::~VertexArrayState()
+{
+    if (_stateObserverSet->getObserverdObject())
+    {
+        _state->resetCurrentVertexArrayStateOnMatch(this);
+    }
+}
+
 void VertexArrayState::generateVertexArrayObject()
 {
     _ext->glGenVertexArrays(1, &_vertexArrayObject);
@@ -539,7 +548,7 @@ void VertexArrayState::deleteVertexArrayObject()
 {
     if (_vertexArrayObject)
     {
-        VAS_NOTICE<<"  VertexArrayState::deleteVertexArrayObject() "<<_vertexArrayObject<<std::endl;
+        VAS_NOTICE<<"  VertexArrayState::deleteVertexArrayObject() "<<_vertexArrayObject<<" "<<_stateObserverSet->getObserverdObject()<<std::endl;
 
         _ext->glDeleteVertexArrays(1, &_vertexArrayObject);
         _vertexArrayObject = 0;