Search found 10 matches

by Jack2016
Fri May 19, 2017 4:48 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: What is the meaning of parameter Kcfm in PGS Formulation?
Replies: 3
Views: 32235

Re: What is the meaning of parameter Kcfm in PGS Formulatio

http://box2d.org/files/GDC2011/GDC2011_Catto_Erin_Soft_Constraints.pdf Thanks, Drik The Paper <<Soft Constraints>> by Erin is very helpful to me. I also find the entire derivation about softness post by Erin https://bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=4&t=1354 v2new = v2damaged + in...
by Jack2016
Wed May 17, 2017 3:11 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: What is the meaning of parameter Kcfm in PGS Formulation?
Replies: 3
Views: 32235

What is the meaning of parameter Kcfm in PGS Formulation?

I read K.Erlenben book <<Stable,Robust And Verstile>> Chapter 6 to learn the PGS in Bullet https://pic3.zhimg.com/v2-5d4c969b50737691ca85e915627f154a_b.png http://bulletphysics.org/Bullet/phpBB3/download/file.php?id=1348 When I see the src code in Bullet, I think the Result of the Equation is the Co...
by Jack2016
Sun Sep 11, 2016 10:06 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Which paper is about GJK-EPA by Nathanael Presson ?
Replies: 2
Views: 4071

Re: Which paper is about GJK-EPA by Nathanael Presson ?

The Expanding Polytope Algorithm (EPA) is by Gino van den Bergen. See "Proximity Queries and Penetration Depth Computation on 3D Game Objects" link/pdf and his book from this page: http://www.dtecta.com/publications Nathan implement this, as well as some improvements. Thanks a lot ,Erwin
by Jack2016
Fri Sep 09, 2016 3:54 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Which paper is about GJK-EPA by Nathanael Presson ?
Replies: 2
Views: 4071

Which paper is about GJK-EPA by Nathanael Presson ?

Nathanael said the algorithm is incremental convex hull, but I can't find paper btGjkEpa2.cpp: EPA::Evaluate() m_status = eStatus::Valid; for (; iterations < EPA_MAX_ITERATIONS; ++iterations) { if (m_nextsv < EPA_MAX_VERTICES) { sHorizon horizon; sSV* w = &m_sv_store[m_nextsv++]; bool valid = tr...
by Jack2016
Wed Aug 24, 2016 9:22 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: How to compute Lateral Friction Direction ?
Replies: 1
Views: 3195

How to compute Lateral Friction Direction ?

After compute the Jacobian of contact point constraint, I compute the Jacobian of friction ,I have to compute the friction Direction Dk whick store in cp.m_lateralFrictionDir1. But it's not clear about why compute this way below btVector3 tbRigidBody::getVelocityInLocalPoint(const btVector3& rel...
by Jack2016
Thu Aug 18, 2016 1:55 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: How to compute BoxBox contact point ?
Replies: 6
Views: 5982

Re: How to compute BoxBox contact point ?

They wrote dBoxBox like that because it made sense to them at the time to write it like that. They probably derive a lot of the math on paper and then translated it into code. If you want to know what c1 - k1 - k3 is then you need to go through the math and draw pictures of what everything is. You ...
by Jack2016
Tue Aug 16, 2016 2:44 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: How to compute BoxBox contact point ?
Replies: 6
Views: 5982

Re: How to compute BoxBox contact point ?

In the func dBoxBox2 ,after SAT it's clear to get the collision type which store in the variable "code" -> 1,2,3 / 4,5,6 /9-15 But then I find it's still not clear about the implementation detail of contact point computing,I read the paper of Erwin GDC10_Contact.pdf The paper just give us ...
by Jack2016
Sat Aug 13, 2016 12:38 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: How to compute BoxBox contact point ?
Replies: 6
Views: 5982

Re: How to compute BoxBox contact point ?

jheanley wrote:This should be a reasonable start, this is OBB vs OBB collisions. (OBB is Oriented Bounding Box, the other type is AABB or axis aligned bounding box which is somewhat cheaper to compute)

http://www.randygaul.net/2014/05/22/der ... ction-sat/
this article is very helpful , Thanks
by Jack2016
Fri Aug 12, 2016 5:55 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: How to compute BoxBox contact point ?
Replies: 6
Views: 5982

How to compute BoxBox contact point ?

when I read the btBoxBoxCollisionAlgorithm source code to compute BoxBox contact points ,I find it's hard to understand.
so which book or paper should I refer to,I want to know the principle first