Does PhysX support ( static ) concave objects?

Please don't post Bullet support questions here, use the above forums instead.
mal
Posts: 16
Joined: Mon Jul 11, 2005 8:39 am
Location: Ireland

Does PhysX support ( static ) concave objects?

Post by mal »

Hi folks,

Apologies for posting this newbie question here.

I'm about to get involved with a project where PhysX is going to be used ( in this case, there is no choice to use another technology like Bullet, it has to be PhysX ).

I've been searching forums, and seem to be getting different answers to this question, so I thought I'd ask the experts directly :)


Does PhysX support static concave objects ( eg is it possible to import an arbitarty irregular doughnut shaped mesh, make it a static collision object, and drop a dynamic box so that the box would collide with the sides, but would drop through the hole in the middle.


On some forums, it states that the concave object has to be broken down into multiple convex shapes ( this isn't an option in this project ), and on others, it seems to state that a height-map like construct can be used for irregular grounds ( which of course won't work with the doughnut example above ).


Your advice is very much appreciated on this matter!

If it is possible, and you have some sample C/C++ code that would create this static convex phsyical object from the triangle mesh, that would be absolutely amazing - I can then pass this on to the company integrating PhysX into the engine, so that they can implement this functionality ( it currently isn't implemented ).

Many thanks...
Mal ( long time user of the excellent Bullet physics engine in the Blender GE )
goruka
Posts: 27
Joined: Wed Nov 07, 2007 12:49 am

Re: Does PhysX support ( static ) concave objects?

Post by goruka »

mal wrote: Does PhysX support static concave objects ( eg is it possible to import an arbitarty irregular doughnut shaped mesh, make it a static collision object, and drop a dynamic box so that the box would collide with the sides, but would drop through the hole in the middle.
I'm sure physx supports trimeshes (collision by triangle in triangle meshes)..

Creating many convex polygons from a concave one is an algorithm nightmare, and I don't recommend it, of course the obvious answer is to do it using BSPs, but it will be extremely unoptimal and not worth it. Creating a convex one that wraps the concave one is easy, but you lose the hole :)

Cheers
Pierre
Posts: 67
Joined: Mon Jul 25, 2005 8:56 am

Re: Does PhysX support ( static ) concave objects?

Post by Pierre »

Does PhysX support static concave objects ( eg is it possible to import an arbitarty irregular doughnut shaped mesh, make it a static collision object, and drop a dynamic box so that the box would collide with the sides, but would drop through the hole in the middle.
Yes.
Creating many convex polygons from a concave one is an algorithm nightmare, and I don't recommend it
Yet that's what PhysX does internally.

- Pierre
Dirk Gregorius
Posts: 861
Joined: Sun Jul 03, 2005 4:06 pm
Location: Kirkland, WA

Re: Does PhysX support ( static ) concave objects?

Post by Dirk Gregorius »

Yet that's what PhysX does internally.
Has the user any control about this? Can the result of the decompositon be verfied somewhere for debugging?
Pierre
Posts: 67
Joined: Mon Jul 25, 2005 8:56 am

Re: Does PhysX support ( static ) concave objects?

Post by Pierre »

Has the user any control about this? Can the result of the decompositon be verfied somewhere for debugging?
Unless things changed, no and no.