Search found 235 matches

by bone
Mon Mar 05, 2007 10:13 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: Ageia paper on position based physics
Replies: 73
Views: 75724

Re: Regularized methods

And specifically at: Interactive simulation of elastic deformable materials at http://www.vrlab.umu.se/research/flexible/ISEDM.pdf I looked at it. As they note, it's really two parts: one is a more physically accurate way to model elastic tetrahedrons, the other is a new integration scheme. I'm sti...
by bone
Thu Mar 01, 2007 9:37 pm
Forum: General Bullet Physics Support and Feedback
Topic: Box falls on its edge. It doesn't come to rest on its face
Replies: 5
Views: 4492

... assuming the CG is directly above the edge, yes?
by bone
Thu Feb 22, 2007 7:06 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Vector Calculus and Constraint Functions
Replies: 27
Views: 19255

On a related note, I'd like to know where the "cardinality" term comes from, it's not explained in the paper very well and I don't understand why it's used.. but it seems necessary. Actually I think this can be explained if you look between equations ( 7 ) and ( 8 ) in the paper. The cardinality is...
by bone
Thu Feb 22, 2007 3:08 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Vector Calculus and Constraint Functions
Replies: 27
Views: 19255

One typical mistake is not to move your points to the origin as the paper states. So let x1, x2, x3, x4 be your particle positions. I did indeed make that mistake early on, but fixed it before encountering my other issue. raigan2 - OK, thanks, I'll try implementing your suggestion. My memory of cal...
by bone
Wed Feb 21, 2007 10:47 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Vector Calculus and Constraint Functions
Replies: 27
Views: 19255

So, has anyone implemented a bend constraint using the "Position Based Dynamics" paper? As of today, yes and no. It's not quite working. Up through eqn (27), everything looks great (the calculated q's are the correct gradient directions). But something's amiss with the scaling term - applying it us...
by bone
Wed Feb 21, 2007 3:03 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: Box2D Demo & Tutorial
Replies: 53
Views: 64777

BioSlayer wrote:This is using Erin Cattos algorithm which I thought was called sequential impulses not split impulses.
To be honest, I've been getting confused between the definitions of these, too.
by bone
Wed Feb 21, 2007 3:01 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: Ageia paper on position based physics
Replies: 73
Views: 75724

Thanks again Antonio and Dirk. I'll chew on that for awhile.
by bone
Tue Feb 20, 2007 9:15 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: Ageia paper on position based physics
Replies: 73
Views: 75724

There is also some coupling between the edge preservation constraints and the volume preservation constraints. Follow-up question on this method: if you scaled the edge lengths in your edge preservation constraint by, say, the ratio of the current-to-original volume, it seems that would help decoup...
by bone
Tue Feb 20, 2007 7:36 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: Ageia paper on position based physics
Replies: 73
Views: 75724

Thank you very much for the guidance. Sorry, yes I said force but I was really looking at implementing it as a constraint.
by bone
Tue Feb 20, 2007 5:23 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: Ageia paper on position based physics
Replies: 73
Views: 75724

Being able to handle distance, planar and volume preservation in a stable way allows you to do very good quality deformable objects. So it might very well be a fast and stable alternative to FEM. People used verlet for years now in cloth and rigidbody context, and this new paper describes a more ge...