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allow to specify constraint limit restitution (bounce/bouncyness) #759

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
Currently there is no properly defined behaviour what happens when a constraint 
reaches the limit, or if the constraint exceeded the limit.

A limit should behave similar to a contact constraint, and we should expose 
similar properties: restitution, 'erp'/baumgarte and 'split impulse' (split 
impulse solves 2 separate LCPs, so that the error recovery doesn't impact the 
velocity)

See also http://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=9502

For some of the constraints, there is some 'fudge factor' hack, similar to the 
one on Open Dynamics Engine, but this doesn't work well and the parameter needs 
to be tuned.

Original issue reported on code.google.com by erwin.coumans on 27 Oct 2013 at 10:08

GoogleCodeExporter commented 9 years ago 
[deleted comment]
GoogleCodeExporter commented 9 years ago 
It should be easy to make constraints soft, and add 'spring' and 'damper' 
parameters, using the CFM and ERP parameters. Currently those parameters are 
not consistently used, it needs to be fixed.

See slide 35, and the rest of the Erin Catto's Game Developers Conference notes 
on soft constraints.
https://code.google.com/p/box2d/downloads/detail?name=GDC2011_Catto_Erin_Soft_Co
nstraints.pdf

Aside from spring and damper, the restitution/'bounce' can also fairly easy be 
implemented.

Original comment by erwin.coumans on 28 Oct 2013 at 3:58

GoogleCodeExporter commented 9 years ago 
Thanks for that link. That was very helpful.

Original comment by davidcof...@gmail.com on 28 Oct 2013 at 4:28

GoogleCodeExporter commented 9 years ago 
Hi.

When you planning to work on this Issue? Can this be soon? Also, can you tell 
me, are ERP/CFM/Stop CFM constraints parameters are working now (particulary 
Hinge constraint) or no?

Original comment by Anton.Br...@gmail.com on 9 Jan 2014 at 11:55

GoogleCodeExporter commented 9 years ago 
I'm going to fix the erp/cfm issue soon. Note that the work is happening in the 
new github repository. I don't know yet wnat I'm going to do with this svn repo 
at googlecode. The current trunk of googlecode/src is basically in 
http://github.com/erwincoumans/bullet3

Original comment by erwin.coumans on 11 Jan 2014 at 12:51

GoogleCodeExporter commented 9 years ago 
moved to https://github.com/bulletphysics/bullet3/issues/65

Original comment by erwin.coumans on 30 Mar 2014 at 5:09