Determinism patch for Bullet Physics in NTRT

determinism_bullet.patch

--- src/BulletCollision/BroadphaseCollision/btAxisSweep3_old.h	2016-10-12 16:39:06.314991696 -0400
+++ src/BulletCollision/BroadphaseCollision/btAxisSweep3.h	2016-10-12 16:38:55.742991000 -0400
@@ -362,8 +362,8 @@ 
 
 	if (!m_pairCache)
 	{
-		void* ptr = btAlignedAlloc(sizeof(btHashedOverlappingPairCache),16);
-		m_pairCache = new(ptr) btHashedOverlappingPairCache();
+		void* ptr = btAlignedAlloc(sizeof(btSortedOverlappingPairCache),16);
+		m_pairCache = new(ptr) btSortedOverlappingPairCache();
 		m_ownsPairCache = true;
 	}
 
--- src/BulletCollision/CollisionDispatch/btSimulationIslandManager_old.cpp	2016-10-12 16:39:48.950992424 -0400
+++ src/BulletCollision/CollisionDispatch/btSimulationIslandManager.cpp	2016-10-12 16:39:36.938992000 -0400
@@ -192,10 +192,40 @@ 
 class btPersistentManifoldSortPredicate
 {
 	public:
+		const btCollisionObjectArray& collisionObjects;
+
+		btPersistentManifoldSortPredicate(btCollisionObjectArray& b): collisionObjects(b)
+		{
+
+		}
+
+		int body_id(const btCollisionObject* obj) const
+		{
+			int id=0;
+			while(true)
+			{
+				if(obj==collisionObjects[id])
+					return id;
+				id++;
+			}
+		}
 
 		SIMD_FORCE_INLINE bool operator() ( const btPersistentManifold* lhs, const btPersistentManifold* rhs ) const
 		{
-			return getIslandId(lhs) < getIslandId(rhs);
+
+			if(body_id(lhs->getBody0())<body_id(rhs->getBody0()))
+				return true;
+			else if(body_id(lhs->getBody0())>body_id(rhs->getBody0()))
+				return false;
+			else
+			{
+				if(body_id(lhs->getBody1())<body_id(rhs->getBody1()))
+					return true;
+				else
+					return false;
+			}
+
+			// return getIslandId(lhs) < getIslandId(rhs);
 		}
 };
 
@@ -379,7 +409,7 @@ 
 
 		//tried a radix sort, but quicksort/heapsort seems still faster
 		//@todo rewrite island management
-		m_islandmanifold.quickSort(btPersistentManifoldSortPredicate());
+		m_islandmanifold.quickSort(btPersistentManifoldSortPredicate(collisionObjects));
 		//m_islandmanifold.heapSort(btPersistentManifoldSortPredicate());
 
 		//now process all active islands (sets of manifolds for now)