BGE Scenegraph and View frustrum culling improvement.

This commit contains a number of performance improvements for the
BGE in the Scenegraph (parent relation between objects in the
scene) and view frustrum culling.

The scenegraph improvement consists in avoiding position update
if the object has not moved since last update and the removal
of redundant updates and synchronization with the physics engine.

The view frustrum culling improvement consists in using the DBVT
broadphase facility of Bullet to build a tree of graphical objects
in the scene. The elements of the tree are Aabb boxes (Aligned 
Axis Bounding Boxes) enclosing the objects. This provides good
precision in closed and opened scenes. This new culling system
is enabled by default but just in case, it can be disabled with
a button in the World settings. There is no do_version in this
commit but it will be added before the 2.49 release. For now you
must manually enable the DBVT culling option in World settings
when you open an old file.

The above improvements speed up scenegraph and culling up to 5x.
However, this performance improvement is only visible when
you have hundreds or thousands of objects.

The main interest of the DBVT tree is to allow easy occlusion
culling and automatic LOD system. This will be the object of further
improvements.

1 files changed, 13 insertions, 2 deletions

diff --git a/source/gameengine/Physics/Bullet/CcdPhysicsEnvironment.h b/source/gameengine/Physics/Bullet/CcdPhysicsEnvironment.h
index 2f1f0bb254b..ddbcbe6b4d6 100644
--- a/source/gameengine/Physics/Bullet/CcdPhysicsEnvironment.h
+++ b/source/gameengine/Physics/Bullet/CcdPhysicsEnvironment.h
@@ -20,6 +20,7 @@ subject to the following restrictions:
 #include <vector>
 #include <set>
 class CcdPhysicsController;
+class CcdGraphicController;
 #include "LinearMath/btVector3.h"
 #include "LinearMath/btTransform.h"
 
@@ -40,6 +41,7 @@ class btDispatcher;
 class WrapperVehicle;
 class btPersistentManifold;
 class btBroadphaseInterface;
+struct btDbvtBroadphase;
 class btOverlappingPairCache;
 class btIDebugDraw;
 class PHY_IVehicle;
@@ -58,7 +60,10 @@ protected:
 	btIDebugDraw*	m_debugDrawer;
 	
 	class btDefaultCollisionConfiguration* m_collisionConfiguration;
-	class btBroadphaseInterface*			m_broadphase;
+    class btBroadphaseInterface*		m_broadphase;	// broadphase for dynamic world
+	// for culling only
+	btOverlappingPairCache*				m_cullingCache;
+	struct btDbvtBroadphase*			m_cullingTree;	// broadphase for culling
 
 	//solver iterations
 	int	m_numIterations;
@@ -77,7 +82,7 @@ protected:
 	void	processFhSprings(double curTime,float timeStep);
 
 	public:
-		CcdPhysicsEnvironment(btDispatcher* dispatcher=0, btOverlappingPairCache* pairCache=0);
+		CcdPhysicsEnvironment(bool useDbvtCulling, btDispatcher* dispatcher=0, btOverlappingPairCache* pairCache=0);
 
 		virtual		~CcdPhysicsEnvironment();
 
@@ -167,6 +172,7 @@ protected:
 		btTypedConstraint*	getConstraintById(int constraintId);
 
 		virtual PHY_IPhysicsController* rayTest(PHY_IRayCastFilterCallback &filterCallback, float fromX,float fromY,float fromZ, float toX,float toY,float toZ);
+		virtual bool cullingTest(PHY_CullingCallback callback, void* userData, PHY__Vector4* planes, int nplanes);
 
 
 		//Methods for gamelogic collision/physics callbacks
@@ -200,7 +206,12 @@ protected:
 
 		void	refreshCcdPhysicsController(CcdPhysicsController* ctrl);
 
+		void	addCcdGraphicController(CcdGraphicController* ctrl);
+
+		void	removeCcdGraphicController(CcdGraphicController* ctrl);
+
 		btBroadphaseInterface*	getBroadphase();
+		btDbvtBroadphase*	getCullingTree() { return m_cullingTree; }
 
 		btDispatcher*	getDispatcher();