Search found 235 matches

by bone
Thu Apr 18, 2013 1:35 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: A verlet based approach for... 3D physics?
Replies: 6
Views: 5280

Re: A verlet based approach for... 3D physics?

Indeed, that's going to be more difficult. Particularly the edge/edge case (when an edge of one cube touches the edge of another cube, yet no verts have penetrated the faces of the other cube). I believe some people just skip that case altogether.
by bone
Tue Apr 16, 2013 5:21 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: A verlet based approach for... 3D physics?
Replies: 6
Views: 5280

Re: A verlet based approach for... 3D physics?

My previous post should have said "connected" not "converted". Anyway ... Your original post said: "it seems that edges code doesnt work for by cube." I'm asking what isn't working. Does the cube collapse? Blow up? In other words, in what way does it not work? I'm guessing it collapses. Also, I don'...
by bone
Mon Apr 15, 2013 9:37 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: A verlet based approach for... 3D physics?
Replies: 6
Views: 5280

Re: A verlet based approach for... 3D physics?

I can't figure out where you're coming up with 18 edges. If every vert in the cube is converted to every other, it should be 28, no? What's not working for you?
by bone
Tue Apr 09, 2013 5:50 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Rope physics with position constraints question
Replies: 4
Views: 10279

Re: Rope physics with position constraints question

If it looks good and the CPU usage isn't causing any problems, I'd say you are done. That being said, yes this could be solved more efficiently with a lot of work (note that I personally don't even consider a timestep of 0.003 seconds to be particularly small; presumably you'd never even go above th...
by bone
Tue Apr 02, 2013 6:57 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Questions about collision response order
Replies: 1
Views: 2906

Re: Questions about collision response order

No, you are only computing the collision response (an impulse) once, based on the current states of both objects. Once you have the impulse, you apply it positively to one object and negatively to the other, and the order is irrelevant.
by bone
Fri Mar 01, 2013 2:50 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Soft constraint derivation
Replies: 19
Views: 18046

Re: Soft constraint derivation

You might do a search on this forum for the same subject on CFM and ERP; I think Dirk and I discussed it previously. IIRC, Box2D uses one derivation (including the h in the coefficients), Bullet does the opposite. Or maybe vice versa. But it can be made to work either way, so if you're deriving it i...
by bone
Mon Oct 15, 2012 4:03 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Stewart & Trinkle - additional resources
Replies: 9
Views: 11524

Re: Stewart & Trinkle - additional resources

Oops, that's who I meant! Please let me know if it hasn't shown up in your inbox.
by bone
Thu Oct 11, 2012 7:29 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Stewart & Trinkle - additional resources
Replies: 9
Views: 11524

Re: Stewart & Trinkle - additional resources

sberard- It turns out I saved a local copy of that rigid_body_lcp.pdf. Either give me a place to upload it or send me a PM with your e-mail addy, it's only about 1.1Mb.
by bone
Fri Sep 14, 2012 2:51 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Cloth collision detection-What is the currnt stateof the art
Replies: 12
Views: 13623

Re: Cloth collision detection-What is the currnt stateof the

jarno wrote:The edge versus edge case can be converted to a vertex versus plane problem by collapsing one edge to a point, and extruding the other edge in the same direction to form a quadrilateral.
A-ha! That's the trick I was missing. Thanks for the idea!
by bone
Thu Sep 13, 2012 7:02 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Cloth collision detection-What is the currnt stateof the art
Replies: 12
Views: 13623

Re: Cloth collision detection-What is the currnt stateof the

Do you mind sharing how you handle the edge-edge case? My version is atrocious, but basically works.
by bone
Mon Aug 27, 2012 9:46 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: New research on real-time deformable body dynamics (FEM).
Replies: 28
Views: 31679

Re: New research on real-time deformable body dynamics (FEM)

This of course all depends on the spectral radius of the problem and the nature of the LCP, but my general experience is that it sucks for anything but perhaps large contact systems, where few other methods can be used at all. I don't know that it necessarily "sucks", but it's fairly well known tha...
by bone
Mon Jul 09, 2012 4:23 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Lagrange multipliers
Replies: 8
Views: 8613

Re: Lagrange multipliers

Erin Catto's demonstration uses velocity-based constraints; I usually think of Lagrange multipliers as used with acceleration-based constraints, but I'm not sure of the exact definition and it could be the same thing. I think if you've modeled constraints, you've either used Lagrange multipliers wit...
by bone
Wed Jun 27, 2012 5:15 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: using fixed-point floating point to represent position
Replies: 2
Views: 4555

Re: using fixed-point floating point to represent position

... or you can basically have the best of all worlds and just use doubles.
by bone
Thu Apr 05, 2012 1:14 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Force Computation Without Velocity
Replies: 1
Views: 3140

Re: Force Computation Without Velocity

If there's no velocity, those impulses are presumably going to be zero. Most game physics engines depend on solving contact impulses to resist penetration by clipping the penetration velocity to zero. I don't know what your application is, but it sort of sounds like you want to estimate the force ba...
by bone
Tue Apr 03, 2012 4:11 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Collisions between Characters Controllers
Replies: 3
Views: 3651

Re: Collisions between Characters Controllers

You might want to go back to the main forum page and read the red text regarding this sub-forum.