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, 17 insertions, 0 deletions

diff --git a/source/gameengine/Ketsji/KX_Scene.h b/source/gameengine/Ketsji/KX_Scene.h
index df51fcec8f7..9f05ddf70c2 100644
--- a/source/gameengine/Ketsji/KX_Scene.h
+++ b/source/gameengine/Ketsji/KX_Scene.h
@@ -85,6 +85,8 @@ class RAS_IRenderTools;
 class SCA_JoystickManager;
 class btCollisionShape;
 class KX_BlenderSceneConverter;
+struct KX_ClientObjectInfo;
+
 /**
  * The KX_Scene holds all data for an independent scene. It relates
  * KX_Objects to the specific objects in the modules.
@@ -92,6 +94,12 @@ class KX_BlenderSceneConverter;
 class KX_Scene : public PyObjectPlus, public SCA_IScene
 {
 	Py_Header;
+
+	struct CullingInfo {
+		int m_layer;
+		CullingInfo(int layer) : m_layer(layer) {}
+	};
+
 protected:
 	RAS_BucketManager*	m_bucketmanager;
 	CListValue*			m_tempObjectList;
@@ -252,6 +260,11 @@ protected:
 	bool m_activity_culling;
 	
 	/**
+	 * Toggle to enable or disable culling via DBVT broadphase of Bullet.
+	 */
+	bool m_dbvt_culling;
+	
+	/**
 	 * The framing settings used by this scene
 	 */
 
@@ -269,6 +282,7 @@ protected:
 	void MarkVisible(SG_Tree *node, RAS_IRasterizer* rasty, KX_Camera*cam,int layer=0);
 	void MarkSubTreeVisible(SG_Tree *node, RAS_IRasterizer* rasty, bool visible, KX_Camera*cam,int layer=0);
 	void MarkVisible(RAS_IRasterizer* rasty, KX_GameObject* gameobj, KX_Camera*cam, int layer=0);
+	static void PhysicsCullingCallback(KX_ClientObjectInfo* objectInfo, void* cullingInfo);
 
 	double				m_suspendedtime;
 	double				m_suspendeddelta;
@@ -530,6 +544,9 @@ public:
 	bool IsSuspended();
 	bool IsClearingZBuffer();
 	void EnableZBufferClearing(bool isclearingZbuffer);
+	// use of DBVT tree for camera culling
+	void SetDbvtCameraCulling(bool b) { m_dbvt_culling = b; };
+	bool GetDbvtCameraCulling() { return m_dbvt_culling; };
 	
 	void SetSceneConverter(class KX_BlenderSceneConverter* sceneConverter);