add ability for user pair callback, this can be used to keep track of objects, overlapping a certain AABB/shape.

src/BulletCollision/BroadphaseCollision/btAxisSweep3.h

@@ -24,7 +24,7 @@
 #include "btOverlappingPairCache.h"
 #include "btBroadphaseInterface.h"
 #include "btBroadphaseProxy.h"
-
+#include "btOverlappingPairCallback.h"
 
 //#define DEBUG_BROADPHASE 1
 
@@ -82,6 +82,10 @@ protected:
 	Edge* m_pEdges[3];						// edge arrays for the 3 axes (each array has m_maxHandles * 2 + 2 sentinel entries)
 
 	btOverlappingPairCache* m_pairCache;
+
+	///btOverlappingPairCallback is an additional optional user callback for adding/removing overlapping pairs, similar interface to btOverlappingPairCache.
+	btOverlappingPairCallback* m_userPairCallback;
+	
 	bool	m_ownsPairCache;
 
 	int	m_invalidPair;
@@ -139,7 +143,14 @@ public:
 		return m_pairCache;
 	}
 
-
+	void	setOverlappingPairUserCallback(btOverlappingPairCallback* pairCallback)
+	{
+		m_userPairCallback = pairCallback;
+	}
+	const btOverlappingPairCallback*	getOverlappingPairUserCallback() const
+	{
+		return m_userPairCallback;
+	}
 };
 
 ////////////////////////////////////////////////////////////////////
@@ -209,6 +220,7 @@ btAxisSweep3Internal<BP_FP_INT_TYPE>::btAxisSweep3Internal(const btPoint3& world
 :m_bpHandleMask(handleMask),
 m_handleSentinel(handleSentinel),
 m_pairCache(pairCache),
+m_userPairCallback(0),
 m_ownsPairCache(false),
 m_invalidPair(0)
 {
@@ -658,6 +670,8 @@ void btAxisSweep3Internal<BP_FP_INT_TYPE>::sortMinDown(int axis, BP_FP_INT_TYPE
 			if (updateOverlaps && testOverlap(axis,pHandleEdge, pHandlePrev))
 			{
 				m_pairCache->addOverlappingPair(pHandleEdge,pHandlePrev);
+				if (m_userPairCallback)
+					m_userPairCallback->addOverlappingPair(pHandleEdge,pHandlePrev);
 
 				//AddOverlap(pEdge->m_handle, pPrev->m_handle);
 
@@ -709,6 +723,9 @@ void btAxisSweep3Internal<BP_FP_INT_TYPE>::sortMinUp(int axis, BP_FP_INT_TYPE ed
 				Handle* handle1 = getHandle(pNext->m_handle);
 
 				m_pairCache->removeOverlappingPair(handle0,handle1,dispatcher);	
+				if (m_userPairCallback)
+					m_userPairCallback->removeOverlappingPair(handle0,handle1);
+				
 			}
 #endif //USE_LAZY_REMOVAL
 
@@ -756,6 +773,8 @@ void btAxisSweep3Internal<BP_FP_INT_TYPE>::sortMaxDown(int axis, BP_FP_INT_TYPE
 				Handle* handle0 = getHandle(pEdge->m_handle);
 				Handle* handle1 = getHandle(pPrev->m_handle);
 				m_pairCache->removeOverlappingPair(handle0,handle1,dispatcher);
+				if (m_userPairCallback)
+					m_userPairCallback->removeOverlappingPair(handle0,handle1);
 			
 #endif //USE_LAZY_REMOVAL		
 
@@ -806,6 +825,8 @@ void btAxisSweep3Internal<BP_FP_INT_TYPE>::sortMaxUp(int axis, BP_FP_INT_TYPE ed
 				Handle* handle0 = getHandle(pEdge->m_handle);
 				Handle* handle1 = getHandle(pNext->m_handle);
 				m_pairCache->addOverlappingPair(handle0,handle1);
+				if (m_userPairCallback)
+					m_userPairCallback->addOverlappingPair(handle0,handle1);
 			}
 
 			// update edge reference in other handle

src/BulletCollision/BroadphaseCollision/btOverlappingPairCallback.h

@@ -0,0 +1,37 @@
+
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+
+#ifndef OVERLAPPING_PAIR_CALLBACK_H
+#define OVERLAPPING_PAIR_CALLBACK_H
+
+///btOverlappingPairCallback provides user callback to keep track of overlap between objects, like a collision sensor
+class btOverlappingPairCallback
+{
+public:
+	virtual ~btOverlappingPairCallback()
+	{
+
+	}
+	
+	virtual void	addOverlappingPair(btBroadphaseProxy* proxy0,btBroadphaseProxy* proxy1) = 0;
+
+	virtual void	removeOverlappingPair(btBroadphaseProxy* proxy0,btBroadphaseProxy* proxy1) = 0;
+
+	virtual void	removeOverlappingPairsContainingProxy(btBroadphaseProxy* proxy0) = 0;
+
+};
+
+#endif //OVERLAPPING_PAIR_CALLBACK_H