Finding nearest polygon normal

Barbalute · Post by **Barbalute** » Wed May 31, 2006 8:44 pm

Hi,
how would I find the normal of the nearest polygon? Some example code would be appreciated but any help would be great.
Thanks

vitek · Post by **vitek** » Thu Jun 01, 2006 7:58 am

Nearest polygon to what?

Barbalute · Post by **Barbalute** » Thu Jun 01, 2006 4:14 pm

To the camera, sorry I should have specified.

vitek · Post by **vitek** » Thu Jun 01, 2006 8:13 pm

I guess it doesn't really matter. You need to get access to its vertex/index buffers.

Use those to find the triangle [set of 3 vertices] that is nearest the point in question. Then you take the normals of those vertices and average them.

Doing this with a brute force search will be slow. You will probably want to use something similar to the octtree triangle selector. Whatever it is, you will need to be able to access the vertex data so you can find the normals.

Travis

Barbalute · Post by **Barbalute** » Thu Jun 01, 2006 8:25 pm

Ok, thanks for all your help. I'd better get started with it then. This could take a little while though

dhenton9000 · Post by **dhenton9000** » Thu Jun 01, 2006 10:47 pm

newtondynamics can be used in collision mode, not physics mode, which might give you a non brute-force method of finding those vertices. I think that collision type packages (coldet) might work as well. RAPID and SOLID might be a bit too much.

BTW, is that Barbalute as in Brown Barbalute?

Barbalute · Post by **Barbalute** » Fri Jun 02, 2006 1:09 am

hm ok I'll look into newtondynamics as well. Thanks for the advice - and yes, it is

bitplane · Post by **bitplane** » Mon Jun 05, 2006 7:02 am

i'm curious.. what do you need the normal of the closest triangle for? perhaps there's a different way around your problem