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.

3 files changed, 16 insertions, 0 deletions

diff --git a/source/gameengine/Rasterizer/RAS_BucketManager.cpp b/source/gameengine/Rasterizer/RAS_BucketManager.cpp
index f7938bb62e6..ec290f89d9e 100644
--- a/source/gameengine/Rasterizer/RAS_BucketManager.cpp
+++ b/source/gameengine/Rasterizer/RAS_BucketManager.cpp
@@ -148,6 +148,10 @@ void RAS_BucketManager::RenderAlphaBuckets(
 
 		while(sit->m_bucket->ActivateMaterial(cameratrans, rasty, rendertools))
 			sit->m_bucket->RenderMeshSlot(cameratrans, rasty, rendertools, *(sit->m_ms));
+
+		// make this mesh slot culled automatically for next frame
+		// it will be culled out by frustrum culling
+		sit->m_ms->SetCulled(true);
 	}
 
 	rasty->SetDepthMask(RAS_IRasterizer::KX_DEPTHMASK_ENABLED);
@@ -170,6 +174,10 @@ void RAS_BucketManager::RenderSolidBuckets(
 
 			while ((*bit)->ActivateMaterial(cameratrans, rasty, rendertools))
 				(*bit)->RenderMeshSlot(cameratrans, rasty, rendertools, *mit);
+
+			// make this mesh slot culled automatically for next frame
+			// it will be culled out by frustrum culling
+			mit->SetCulled(true);
 		}
 	}
 	
diff --git a/source/gameengine/Rasterizer/RAS_FramingManager.h b/source/gameengine/Rasterizer/RAS_FramingManager.h
index 610bd13ff12..0a226ac30f9 100644
--- a/source/gameengine/Rasterizer/RAS_FramingManager.h
+++ b/source/gameengine/Rasterizer/RAS_FramingManager.h
@@ -163,6 +163,13 @@ struct RAS_FrameFrustum
 	float x2,y2;
 };	
 
+/* must match R_CULLING_... from DNA_scene_types.h */
+enum RAS_CullingMode
+{
+	RAS_CULLING_DBVT = 0,
+	RAS_CULLING_NORMAL,
+	RAS_CULLING_NONE
+};
 
 /**
  * @section RAS_FramingManager
diff --git a/source/gameengine/Rasterizer/RAS_MaterialBucket.h b/source/gameengine/Rasterizer/RAS_MaterialBucket.h
index 475f01d549a..211770318ae 100644
--- a/source/gameengine/Rasterizer/RAS_MaterialBucket.h
+++ b/source/gameengine/Rasterizer/RAS_MaterialBucket.h
@@ -156,6 +156,7 @@ public:
 	bool Join(RAS_MeshSlot *target, MT_Scalar distance);
 	bool Equals(RAS_MeshSlot *target);
 	bool IsCulled();
+	void SetCulled(bool culled) { m_bCulled = culled; }
 };
 
 /* Used by RAS_MeshObject, to point to it's slots in a bucket */