Hello, I'm playing with XNA for a game project of myself, I had previous exposure to OpenGL and worked a bit with Ogre, so I'm trying to get the same concepts working on XNA.

Specifically I'm trying to add to XNA a scene manager to handle hierarchical transforms, frustum (maybe even occlusion) culling and transparency object sorting.

My plan was to build a tree scene manager to handle hierarchical transforms and lighting, and then use an Octree for frustum culling and object sorting. The problem is how to do geometry sorting to support transparencies correctly. I know that sorting is very expensive if done on a per-polygon basis, so expensive that it is not even managed by Ogre. But still images from Ogre look right.

Any ideas on how to do it and which data structures to use and their capabilities? I know people around is using:

• Octrees
• Kd-trees (someone on GameDev forum said that these are far better than Octrees)
• BSP (which should handle per-polygon ordering but are very expensive)
• BVH (but just for frustum and occlusion culling)

Thank you

Tunnuz