add support for premade aabb in btStridingMeshInterface/btBvhTriangleMeshShape,

Thanks Roy Eltham, http://code.google.com/p/bullet/issues/detail?id=70

src/BulletCollision/CollisionShapes/btBvhTriangleMeshShape.cpp

@@ -30,7 +30,14 @@ m_ownsBvh(false)
 #ifndef DISABLE_BVH
 
 	btVector3 bvhAabbMin,bvhAabbMax;
+	if(meshInterface->hasPremadeAabb())
+	{
+		meshInterface->getPremadeAabb(&bvhAabbMin, &bvhAabbMax);
+	}
+	else
+	{
 		meshInterface->calculateAabbBruteForce(bvhAabbMin,bvhAabbMax);
+	}
 	
 	if (buildBvh)
 	{

src/BulletCollision/CollisionShapes/btStridingMeshInterface.h

@@ -76,6 +76,10 @@ class  btStridingMeshInterface
 		virtual void	preallocateVertices(int numverts)=0;
 		virtual void	preallocateIndices(int numindices)=0;
 
+		virtual bool	hasPremadeAabb() const { return false; }
+		virtual void	setPremadeAabb(const btVector3& aabbMin, const btVector3& aabbMax ) const {}
+		virtual void	getPremadeAabb(btVector3* aabbMin, btVector3* aabbMax ) const {}
+
 		const btVector3&	getScaling() const {
 			return m_scaling;
 		}

src/BulletCollision/CollisionShapes/btTriangleIndexVertexArray.cpp

@@ -76,3 +76,21 @@ void	btTriangleIndexVertexArray::getLockedReadOnlyVertexIndexBase(const unsigned
 	indicestype = mesh.m_indexType;
 }
 
+bool	btTriangleIndexVertexArray::hasPremadeAabb() const
+{
+	return (m_hasAabb == 1);
+}
+
+void	btTriangleIndexVertexArray::setPremadeAabb(const btVector3& aabbMin, const btVector3& aabbMax )
+{
+	m_aabbMin = aabbMin;
+	m_aabbMax = aabbMax;
+	m_hasAabb = 1; // this is intentionally an int see notes in header
+}
+
+void	btTriangleIndexVertexArray::getPremadeAabb(btVector3* aabbMin, btVector3* aabbMax ) const
+{
+	*aabbMin = m_aabbMin;
+	*aabbMax = m_aabbMax;
+}
+

src/BulletCollision/CollisionShapes/btTriangleIndexVertexArray.h

@@ -51,14 +51,16 @@ ATTRIBUTE_ALIGNED16( class) btTriangleIndexVertexArray : public btStridingMeshIn
 {
 protected:
 	IndexedMeshArray	m_indexedMeshes;
-	int m_pad[3];
-
+	int m_pad[2];
+	int m_hasAabb; // using int instead of bool to maintain alignment
+	btVector3 m_aabbMin;
+	btVector3 m_aabbMax;
 
 public:
 
 	BT_DECLARE_ALIGNED_ALLOCATOR();
 
-	btTriangleIndexVertexArray()
+	btTriangleIndexVertexArray() : m_hasAabb(0)
 	{
 	}
 
@@ -103,6 +105,10 @@ public:
 	virtual void	preallocateVertices(int numverts){(void) numverts;}
 	virtual void	preallocateIndices(int numindices){(void) numindices;}
 
+	virtual bool	hasPremadeAabb() const;
+	virtual void	setPremadeAabb(const btVector3& aabbMin, const btVector3& aabbMax );
+	virtual void	getPremadeAabb(btVector3* aabbMin, btVector3* aabbMax ) const;
+
 }
 ;
 

src/BulletCollision/CollisionShapes/btTriangleMeshShape.cpp

@@ -23,9 +23,16 @@ subject to the following restrictions:
 
 btTriangleMeshShape::btTriangleMeshShape(btStridingMeshInterface* meshInterface)
 : m_meshInterface(meshInterface)
+{
+	if(meshInterface->hasPremadeAabb())
+	{
+		meshInterface->getPremadeAabb(&m_localAabbMin, &m_localAabbMax);
+	}
+	else
 	{
 		recalcLocalAabb();
 	}
+}
 
 
 btTriangleMeshShape::~btTriangleMeshShape()