Search found 9 matches

by DanielJosephTracy
Wed Jun 15, 2011 2:12 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Broad Phase Performance
Replies: 7
Views: 11856

Re: Broad Phase Performance

Alright, the tester is available at the following link: http://www.danieljosephtracy.com/Daniel_Joseph_Tracy/Sweep_and_Prune_files/BroadPhaseCD.zip I didn't have time to do a lot with it. It still has a lot of tweaks and knobs for various potential changes, etc. It's also fairly heavily templated, s...
by DanielJosephTracy
Sun Jun 12, 2011 10:28 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Broad Phase Performance
Replies: 7
Views: 11856

Re: Broad Phase Performance

I did only update objects that were moving, for both algorithms. I didn't change any of the default settings of the algorithm, except I did turn off the feature that increases AABB sizes slightly, allowing me to verify the output. I believe that it uses the hash-based paircache by default, if I reme...
by DanielJosephTracy
Thu Jun 02, 2011 5:23 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Broad Phase Performance
Replies: 7
Views: 11856

Re: Broad Phase Performance

"My problem with SAP is that it doesn't handle varying object sizes well. Your demo seems to use boxes between 3 and 7 units (not sure what you used in your benchmarks). Imagine you have object sizes between 1 and 100 units. Then the SAP will have to check large intervals on insertion and deletion. ...
by DanielJosephTracy
Wed Jun 01, 2011 8:05 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Reducing overhead of resting bodies
Replies: 8
Views: 7316

Re: Reducing overhead of resting bodies

"Thanks for sharing your thoughts,
Erwin"

Thank you for your interest. I did some broad phase testing based on your statement above about Bullet's DBVT approach vs MultiSAP, so I put up another topic:

http://bulletphysics.org/Bullet/phpBB3/ ... f=4&t=6863

Daniel
by DanielJosephTracy
Wed Jun 01, 2011 8:01 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Broad Phase Performance
Replies: 7
Views: 11856

Broad Phase Performance

Erwin: you suggested the following in another thread: "Dynamic aabb tree based broadphase is better than multisap in general. Non-moving objects are free and it can handle moving objects better." I did some work on sweep and prune a few years ago and have a nice implementation of MultiSAP. I decided...
by DanielJosephTracy
Fri May 27, 2011 11:19 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Reducing overhead of resting bodies
Replies: 8
Views: 7316

Re: Reducing overhead of resting bodies

"Does Step 2 (For each object pair overlapping) traverse sleeping pairs?" No. It traverses the object pairs that form the output of the narrow phase. Remember that the narrow phase is performed only between pairs of objects in which at least one are active. So that will contain some sleeping objects...
by DanielJosephTracy
Wed May 25, 2011 4:20 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Reducing overhead of resting bodies
Replies: 8
Views: 7316

Re: Reducing overhead of resting bodies

"Do you rebuild union find from scratch each frame?" Yes, but only active bodies and bodies in contact with them are added. I'm assuming that we're talking about union-find to construct contact groups or "islands" in ODE terminology. The union-find structure begins empty. Here is what we do from the...
by DanielJosephTracy
Tue May 24, 2011 11:12 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Reducing overhead of resting bodies
Replies: 8
Views: 7316

Re: Reducing overhead of resting bodies

"Interesting, for island generation you use a hash map, instead of union find." No, I use union-find just as you do. The hash map stores broad phase overlaps. The union-find algorithm is incrementally constructed as I said starting with active objects and increasing as objects are activated. "I'm us...
by DanielJosephTracy
Tue May 24, 2011 9:42 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Reducing overhead of resting bodies
Replies: 8
Views: 7316

Reducing overhead of resting bodies

Erwin and I chatted a bit in the tail end of the Issue below, and he suggested that we continue in the Bullet public forum. The best way to acquire context is reading the Issue: http://code.google.com/p/bullet/issues/detail?id=128 "The Bullet broadphase have a addPair and removePair. When adding a p...