Jump to content
  • Advertisement
Sign in to follow this  
mincomp

Question about getting collision normals from bvh

This topic is 2059 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hi all,

I'm working on a small rigid body simulator, and this has been a long haunting problem for me: how do I get penetration normal from a bvh. Eventually, by traversing the structure, we can get all pairs of intersecting triangles, however we still don't know if each of the six vertices (from each pairs of triangles) are inside or outside the object itself, nor the normal to the object surface.

I thought I can solve this problem by using a signed distance field, where the inside test is straightforward and the normal can be acquired from discrete differentiation with near by cells, however, when constructing the distance field, I still need to know if a point is inside the object or not. I used to assume the object to be convex (and the problem is easy to solve), and when I move to concave objects, it seems to be very difficult. The ray shooting method is slow and not robust enough, what's worse is that I got some models that are not simple polyhedrons (meaning that the object has multiple components and there are welding edges between them, so that some triangles might be inside the object!)

So after all, my questions is: how to decide if a point is inside/outside the object with BVH, assuming the polyhedrons are normal (those irregular ones can be decomposed)? I know BSP can do this, however I believe BVH can do it as well, otherwise there won't be SO much literature about BVH-based collision detection, the weird thing is that almost nobody mentioned this problem among the literature I searched, am I just being paranoid to solve a irrelevant problem? The only reference I found about this problem is "A Fast Method for Local Penetration Depth Computation" from M.C. Lin, which is somewhat over complicated to me. A quick distance field construction reference is welcome as well.
Or are there other ways to pass around the problem and get the collision normals directly from BVH?

Many thanks in advance!!

Share this post


Link to post
Share on other sites
Advertisement
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!