Search found 10 matches

by Adrian Lopez
Mon May 08, 2017 3:37 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Johnson's distance algorithm: can't find smallest simplex
Replies: 4
Views: 40258

Re: Johnson's distance algorithm: can't find smallest simple

Hi Gino, I'm already checking for duplicate support points as suggested in your book, to prevent GJK from looping indefinitely*. I'm not checking for the closest point being significantly closer to the origin than the last closest point, but Erwin suggested that too in a different thread so it's som...
by Adrian Lopez
Tue May 02, 2017 2:23 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Johnson's distance algorithm: can't find smallest simplex
Replies: 4
Views: 40258

Re: Johnson's distance algorithm: can't find smallest simple

I have added some comments to make the code a bit easier to understand. I should probably do a little refactoring.
by Adrian Lopez
Mon May 01, 2017 11:30 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Johnson's distance algorithm: can't find smallest simplex
Replies: 4
Views: 40258

Johnson's distance algorithm: can't find smallest simplex

I'm having a problem with Johnson's distance algorithm where it sometimes fails to find the smallest simplex containing the point that is closest to the origin. In 2D, this means I get a simplex of size 3 that does not surround the origin and can't be reduced any further by the algorithm (as impleme...
by Adrian Lopez
Thu Apr 20, 2017 1:31 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: GJK: reappearing support points and termination condition
Replies: 2
Views: 7798

Re: GJK: reappearing support points and termination conditio

I'm not checking for progress toward the origin right now, but I'm doing everything suggested by Gino in his "numerical GJK" example. Also, I'm doing this in 2D so I exit as soon as the reduced simplex becomes a triangle. Here's what my GJK function looks like right now, including all term...
by Adrian Lopez
Wed Apr 19, 2017 5:23 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: GJK: reappearing support points and termination condition
Replies: 2
Views: 7798

GJK: reappearing support points and termination condition

I'm having a problem in my GJK implementation where support points reappear periodically in an endless loop, a situation described in pages 143 - 145 of Gino's book, Collision Detection in Interactive 3D Environments . I have added the check for duplicate vertices described in page 145 of the book, ...
by Adrian Lopez
Fri Jul 24, 2015 6:10 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Johnson's Distance Algorithm: What am I doing wrong?
Replies: 1
Views: 5870

Johnson's Distance Algorithm: What am I doing wrong?

Given a simplex {y1, y2} where: y1 = (1,-1) y2 = (1,1) The closest point of its affine hull to the origin should be (1, 0), but that's not what I get: Δ1 = 1 Δ2 = Δ1 * ((y1 - y2) . y1) = 2 Δx = Δ1 + Δ2 = 3 λ1 = Δ1/Δx = 1/3 λ2 = Δ2/Δx = 2/3 v = λ1*y1 + λ2*y2 = (1, 1/3) I must be doing something wrong...
by Adrian Lopez
Wed Dec 03, 2014 4:42 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Continuous GJK for spherically extended objects
Replies: 1
Views: 6486

Continuous GJK for spherically extended objects

Is there a way to perform a ray cast as described in Gino Van Den Bergen's Ray Casting against General Convex Objects , against spherically extended objects without having to calculate support points for the enlarged objects? With GJK you can adjust the termination condition to account for the sligh...
by Adrian Lopez
Sun Apr 18, 2010 9:21 pm
Forum: General Bullet Physics Support and Feedback
Topic: ClosestNotUsRayResultCallback (code)
Replies: 2
Views: 3880

Re: ClosestNotUsRayResultCallback (code)

BTW - Is there an official place to submit contributed code?
by Adrian Lopez
Fri Apr 16, 2010 2:46 am
Forum: General Bullet Physics Support and Feedback
Topic: ClosestNotUsRayResultCallback (code)
Replies: 2
Views: 3880

ClosestNotUsRayResultCallback (code)

I wish to contribute the following code to Bullet's official sources. This code is based on Bullet's own btKinematicClosestNotMeRayResultCallback, but any part of it that may be considered original I hereby place into the public domain. ClosestNotUsRayResultCallback.h: #ifndef CLOSESTNOTUSRAYRESULTC...