## Search found 214 matches

Wed Apr 20, 2022 12:44 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: 10 Minute Physics
Replies: 1
Views: 392

### 10 Minute Physics

I just wanted to put this on everyone's radar: Matthias Muller has been making a really awesome series of tutorials (videos, slides, and source code) working through Position Based Dynamics; a great resource for anyone wanting to implement it. https://matthias-research.github.io/pages/tenMinutePhysi...
Thu Feb 24, 2022 4:23 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Where do you get the data to put in the inertial tag in MuJoCo?
Replies: 1
Views: 1515

### Re: Where do you get the data to put in the inertial tag in MuJoCo?

I don't know if this is true (never used MuJoCo) but given the nature of the other data, I suspect "pos" is the position of the center of mass in the local frame. So for a cube it would be the point in the very center of the cube, equidistant to all faces.
Wed Nov 04, 2020 8:47 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: recent PBD papers
Replies: 1
Views: 6796

### recent PBD papers

I've been getting back into sim/pbd stuff after nearly a decade, and there have been a couple really interesting Position Based Dynamics papers released recently that I wanted to put on everyone's radar: This one is really mind-blowing -- tiny time steps with a single-solver-iteration per step behav...
Thu Jun 29, 2017 8:47 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Position Based Meshless Plasticity
Replies: 4
Views: 11946

### Re: Position Based Meshless Plasticity

Have you tried the approach described in Muller "Meshless Deformations Based on Shape Matching"? AFAIK that's a popular way to implement meshless soft bodies with plastic deformations in a position-based simulation that might be worth a look. This paper from the same author has some useful...
Tue Apr 25, 2017 1:54 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Impulse-based vs force-based constraint solvers
Replies: 7
Views: 13724

### Re: Impulse-based vs force-based constraint solvers

In my limited experience, some types of behaviour are awkward to model with position-based constraints -- for example, friction. I vaguely recall that motors were also a problem, but it's been so long I can't really remember the details! I definitely remember thinking "behaviours that are natur...
Mon Sep 14, 2015 6:30 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: continuous collision detection(point of collision;
Replies: 2
Views: 4446

### Re: continuous collision detection(point of collision;

Erin Catto's GDC2013 presentation on "bilateral advancement" might be worth checking out: http://box2d.org/files/GDC2013/ErinCatto_GDC2013.zip

(he uses distance queries rather than SAT, but maybe the general idea is useful..)
Sun Aug 02, 2015 1:01 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Jacobsen & Verlet - embedding simplex in polytopes
Replies: 7
Views: 8045

### Re: Jacobsen & Verlet - embedding simplex in polytopes

You're welcome! (We're Metanet Software http://www.metanetsoftware.com/blog/ ) We made a couple crappy vids using this solver, but then kind of got burnt out. I'm hoping to revisit it sometime though, it had a lot of potential IMO! https://www.youtube.com/watch?v=YHVyg2rDBy4 https://www.youtube.com/...
Fri Jul 31, 2015 12:40 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Jacobsen & Verlet - embedding simplex in polytopes
Replies: 7
Views: 8045

### Re: Jacobsen & Verlet - embedding simplex in polytopes

Cheers! This stuff was such a headache to figure out that I'm glad to help someone avoid that as much as possible :) I still think that it's "geometry embedded in particles" (or really, "geometry embedded in frame derived from particle positions") and not the other way around, be...
Tue Jul 28, 2015 12:19 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Jacobsen & Verlet - embedding simplex in polytopes
Replies: 7
Views: 8045

### Re: Jacobsen & Verlet - embedding simplex in polytopes

That's very interesting. You wouldn't happen to remember any of those approaches..? Just the stick-based one I described (and, we have a few other weird IK-based embeddings, where the collision geometry is a function of the length between two particles connected via min/max distance constraint). As...
Sun Jul 26, 2015 7:36 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Jacobsen & Verlet - embedding simplex in polytopes
Replies: 7
Views: 8045

### Re: Jacobsen & Verlet - embedding simplex in polytopes

I've done this a couple different ways in 2d, I'm unfortunately really busy at work but I'll try to explain what I know and hopefully it gives you some ideas. (also it's been about 5 years..) In general you have some collision geometry which is embedded in a frame, so the geometry is a function of t...
Sat Nov 15, 2014 6:08 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Verlet collision by particle path ray.
Replies: 9
Views: 10633

### Re: Verlet collision by particle path ray.

Do your particles have a radius/thickness? This would probably help make things behave a bit better. One thing I've done in the past to make particle collision a bit less fussy is to raycast using a thick ray (which has a radius smaller than the full size of the particle), and stop at the moment of ...
Mon Sep 29, 2014 12:17 am
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: Projective Dynamics
Replies: 3
Views: 11328

### Re: Projective Dynamics

Cool, thanks for the heads-up!
Thu Sep 25, 2014 8:35 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Inequality Constraint in PBD
Replies: 4
Views: 5944

### Re: Inequality Constraint in PBD

If your state is within the valid region: the constraint isn't violated, you don't have to do anything. If your state is outside the valid region: find the point on the surface of the valid region closest to the current state, this is your target state. So, for a min/max distance constraint: if(curr...
Thu Sep 25, 2014 8:29 am
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: Projective Dynamics
Replies: 3
Views: 11328

### Projective Dynamics

Just came across this and thought it might be of interest:

"Projective Dynamics: Fusing Constraint Projections for Fast Simulation"
http://lgg.epfl.ch/~bouaziz/pdf/Project ... PH2014.pdf