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Bsp generation question

Started by NeoKenobi Oct 27, 2004 at 2:40 AM 2 replies 1.3k views

Original Post

Oct 27, 2004 at 2:40 AM

I'm writing a program to generate a bsp-tree from a set of geometry. I have a question about the splitting of polygons to divide them into the front and back polygons for a partition-plane. What do you do if a polygon is actually on the splitting-plane? Do you put it in the front or back for this plane? I've read some bsp-documents and none of them handles this case. I'm hoping someone can provide an answer to this simple question. Thanks in advance.

oliii

270

oliii

Oct 27, 2004 at 2:56 AM

should depends which way the normal of the polygon is facing.

if it's facing towards the front the of splitting plane, then it's to the front, else, belongs to the back. If double sided, belongs to both :)

NeoKenobi

Author

NeoKenobi

Oct 27, 2004 at 5:57 AM

Thanks, that's the information I needed.

Oct 29, 2004 at 10:13 AM

If you put it into one of the sub-trees you're building a leaf-based bsp tree. Alternatively, you could save a list of polygons on the splitting plane for each node. A disadvantage of leaf-based trees is that you possibly have to split the polygons on the node's plane further (more polygons in total) which you don't need to do with the node-based tree.
It depends on your application which method is more appropriate.

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