Search found 95 matches

by DevO
Wed Aug 20, 2014 7:39 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Position based dynamics problem
Replies: 1
Views: 2814

Re: Position based dynamics problem

Hi,

I have read this question several times but still do not really understand it.
But IMHO Position Based Methods have a lot of advantages compared to other.
by DevO
Wed Aug 20, 2014 7:37 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Regarding concave collision detection (Chap 10 RTCD)[SOLVED]
Replies: 2
Views: 2445

Re: Regarding concave collision detection (Chap 10 RTCD)[SOL

"Real-Time Collision Detection" is one of my favorite books in this field.
Do some one know other books like this one ?
by DevO
Wed Aug 20, 2014 7:35 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Position-based Elastic Rod
Replies: 10
Views: 10737

Re: Position-based Elastic Rod

> I think a lot of people are still checking this forum, but few are posting new questions. I was not active in thins field for longer time. Are there any other active forums where one could ask such question ? Of course not this one :) Fortunately I was able to implement it and it run very stable n...
by DevO
Sat Aug 16, 2014 5:53 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Position-based Elastic Rod
Replies: 10
Views: 10737

Re: Position-based Elastic Rod

I finally got it now to work.

The solution was actually in "4. Variational interpretation of constraint enforcement" section of the paper, that I have ignored first.

By the way is this forum still active ?
by DevO
Thu Aug 14, 2014 2:00 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Position-based Elastic Rod
Replies: 10
Views: 10737

Position-based Elastic Rod

Hi All, Right now I am trying to understand and implement "Position-based Elastic Rod" from here: http://www-ui.is.s.u-tokyo.ac.jp/~ume/PositionBasedElasticRod/2014_sca_PositionBasedElasticRod.html The only problem is the most important Anisotropic Bending-twisting constraint. (Equation 21 in the pa...
by DevO
Tue Jul 26, 2011 1:09 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: My explicit euler cloth code
Replies: 49
Views: 38882

Re: My explicit euler cloth code

Hi,
please lock at this version.
I just wanted to test one idea regarding float precision and summation.
by DevO
Mon Jul 25, 2011 1:53 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: My explicit euler cloth code
Replies: 49
Views: 38882

Re: My explicit euler cloth code

I dont get this, are u talking about this http://image.diku.dk/kenny/download/kel ... e.ea10.pdf. Yes I am talking about this paper. Please lock at page 5 to Figure 6: algorithm create-bending-constraints and read 4.1. Working with Triangle Meshes . The constrain should not for an triangle that you...
by DevO
Mon Jul 25, 2011 1:26 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: My explicit euler cloth code
Replies: 49
Views: 38882

Re: My explicit euler cloth code

Anyways, why do u recalculate the mass each iteration when it is a constant? Because this calculation is really cheap, to store and the query need more time and memory as to recalculate it. Yes now witch transpose() it should be correct. In you code you still use constant mass but this is not corre...
by DevO
Mon Jul 25, 2011 10:25 am
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: My explicit euler cloth code
Replies: 49
Views: 38882

Re: My explicit euler cloth code

Hi, the parer equation should be correct! I was using it and it was working for me. This should work. delVi = Vcm + cross(w,Ri )-V This line appears to be wrong. I += glm::outerProduct(ri, ri)*mass; Cross product Matrix There could also be numerical problems because of accumulation. Kdamp =1.0 actua...
by DevO
Sun Jul 24, 2011 4:24 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: My explicit euler cloth code
Replies: 49
Views: 38882

Re: My explicit euler cloth code

Hi mobeen, I have mode some changes to you code, so it locks more like PBD. Unfortunately it is still not not fully correct. For example you "center of mass's damping" seems to be broken. New array W is to store inverse particle mass if this is zero then particle is fixed and will not move but the c...
by DevO
Fri Jul 22, 2011 11:21 am
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: My explicit euler cloth code
Replies: 49
Views: 38882

Re: My explicit euler cloth code

Hi mobeen, I think that you triangle order is the source of you problems. This bending constraint will only work if all triangles have the same orientation, ether all CW or all CCW. The phi0 should be 0.0 for the plane. For d==-1 special case in the condition when I need to move vertex 1 and 2, are ...
by DevO
Thu Jul 21, 2011 3:30 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: My explicit euler cloth code
Replies: 49
Views: 38882

Re: My explicit euler cloth code

The method presented in this paper is probably only a bit slower as a simple distance constraint. A Triangle Bending Constraint Model for Position-Based Dynamics Probably one could use the same optimisation to remove Sqrt() as in distance constraint too. One problem is if the angle is 0° then it doe...
by DevO
Thu Jul 21, 2011 2:57 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: My explicit euler cloth code
Replies: 49
Views: 38882

Re: My explicit euler cloth code

HI DevO, Thanks for the reply once again. Are these special cases discussed in the pos based dynamics paper? Atleast, I could not find it. I will read through the other paper to see if it has something to offer. What do u suggest how to handle these cases? No the special cases are usually ignored i...
by DevO
Thu Jul 21, 2011 2:00 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: My explicit euler cloth code
Replies: 49
Views: 38882

Re: My explicit euler cloth code

For the special case, d==-1, this means that the triangles are facing in the opposite direction? Yes this is correct. Probably the code should better look like this. d = glm::dot(n1,n2); //try to catch invalid values that will return NaN. // sqrt(1 - (1.0001*1.0001)) = NaN // sqrt(1 - (-1.0001*-1.0...
by DevO
Thu Jul 21, 2011 12:51 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: My explicit euler cloth code
Replies: 49
Views: 38882

Re: My explicit euler cloth code

You should test for degenerate and special cases, may be this is why you cloth mesh disappears. Why do you use this ? float q1_len = glm::length(q1); //Sqrt (q1_len*q1_len) and not this float q1_slen = glm::length2(q1); //no Sqrt void UpdateBendingConstraint(int index) { size_t i=0; BendingConstrain...