Search found 34 matches

by Etherton
Sun Mar 11, 2007 3:14 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: accuracy of collision detection: Bullet vs. Solid
Replies: 17
Views: 8336

In hindsight everything is always better. The post was edited. Basically it was stating that collision in bullet is better than collision in any other package (other than Havok and Physx) implementing closest feature algorithm, which is simple false. Perhaps if you read the post carefully you will s...
by Etherton
Wed Mar 07, 2007 6:14 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: accuracy of collision detection: Bullet vs. Solid
Replies: 17
Views: 8336

I think you should also mention that those bullet points are not facts, they are your own personal opinions, and it is unlike they have any base on any rigorous analysis.
by Etherton
Mon Mar 05, 2007 8:33 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: GPU Physics fun: rigid body, fluids and 1.000.000 particles
Replies: 22
Views: 18700

Wow I just run the demo, and I have to say that this is without a doubt that fastest and the more stable staking demonstration I had ever seen. I mean those pyramid not more a pixel while they are stacked, until they are touched by the box projectile, when they collapse to the floor. It seems his me...
by Etherton
Fri Mar 02, 2007 1:25 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Interesting, bit outdated Physics Engine comparison paper
Replies: 20
Views: 20979

To start with, the main interest of mine and my colleagues is not game physics, but simulator physics (medical, vehicle, robotic, VR, etc) and here the requirements are not the same as in games. For these areas, there still aren't many alternatives to Bullet, ODE, Havok, Newton and Ageia. The one a...
by Etherton
Tue Feb 27, 2007 12:59 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Interesting, bit outdated Physics Engine comparison paper
Replies: 20
Views: 20979

I think that as long as all criteria are included in the test scenes, then it is irrelevant whether they test correctness or not, because it will be embedded in the input data. A particular API will get a score that can be low or high on scenes that emphasizes the correctness aspect. It will be like...
by Etherton
Wed Jan 31, 2007 5:46 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Collision detection libraries
Replies: 11
Views: 6518

Pierre wrote:With a refit operation, same as Solid. Only faster since the trees have less nodes to refit.
...

Pierre
Umm I was under the impression that an AABB struture was bound to have equal or more nodes than an OBB. Maybe I was wrong on that.
by Etherton
Wed Jan 10, 2007 7:50 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Split Impulses and Joints
Replies: 53
Views: 28577

A common misconception is that you cannot have constraints on top of Featherstone. But you can! You can have: - loops - contact - motors and limits You can solve these extra constraints with any LCP solver (PGS, SI, etc). sound like the silver bullet (no pun intended) Then why not using Featherston...
by Etherton
Mon Jan 08, 2007 6:12 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Physics Engines comparisons and benchmarks
Replies: 3
Views: 3087

aboeing wrote:you can try pal:
http://pal.sourceforge.net/
The link to pal since to be about the doxigen doc only, how can I download the application?
by Etherton
Sat Nov 25, 2006 3:22 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Pricing strategy of a physics engine (Meqon testcase)
Replies: 4
Views: 3741

It sure strikes a devastating blow to all middleware developers. It looks more an act of desperation to attract attention before Ati and Nvidia GPU/Stream processors become mainstream among all middleware developers. In no way a smart move that will increase the market penetration of dedicated physi...
by Etherton
Thu May 25, 2006 4:58 pm
Forum: General Bullet Physics Support and Feedback
Topic: collision with very big static object
Replies: 13
Views: 11176

You are probably right and I am wrong. :(
by Etherton
Wed May 24, 2006 1:41 pm
Forum: General Bullet Physics Support and Feedback
Topic: collision with very big static object
Replies: 13
Views: 11176

You misunderstood. It is trivially the case that we can have two expressions, A and B, which are different looking but mathematically equivalent, and where one has less numerical errors than the other. Obviously, by rewriting A as B (or B as A) you can achieve the same error, but that presupposes (...
by Etherton
Tue May 23, 2006 11:37 pm
Forum: General Bullet Physics Support and Feedback
Topic: collision with very big static object
Replies: 13
Views: 11176

Very good maybe now you can document that Bullet does not have the limitation that Havok and Ageia has in its GJK. I think that Bullet is a very good library and before it, there were only three legs on physics: Havok, Agia and ODE, now with Bullet quatrenium is completed. :D PS: On the bright side ...
by Etherton
Tue May 23, 2006 7:48 pm
Forum: General Bullet Physics Support and Feedback
Topic: collision with very big static object
Replies: 13
Views: 11176

ODE uses SAT, so it is not using GJK (yet). Maybe I am wrong but I think I did play a test demo with bullet integration. Anyway when you add bullet to ODE/Bullet combined will probably be the best physicist solution ever implemented. I am just salivating for that. :D Where was this assumed? Except ...
by Etherton
Tue May 23, 2006 5:24 pm
Forum: General Bullet Physics Support and Feedback
Topic: collision with very big static object
Replies: 13
Views: 11176

The GJK implementation has some limitations for large size ratios. As most physics engines, there are several restrictions and rules, and those should be documented and explained. It's best to keep the object sizes between 0.25 units, and at most 50 units. Also, mass ratios should be fairly small, ...
by Etherton
Thu May 04, 2006 9:21 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Baraff's LCP solver with friction
Replies: 7
Views: 6887

edit:
agree, I think you are right No argument here either.