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btSequentialImpulseConstraintSolver does not provide option to randomize non-contact constraints #576

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
What steps will reproduce the problem?

Replace ConstraintDemo.cpp with version in linked thread and fire cubes at the 
centre of the constraint array.

What is the expected output? What do you see instead?

The angular motors should kill the velocity in the 6dof constraints, instead 
the entire system becomes unstable.

What version of the product are you using? On what operating system?

Trunk on Linux 64bit.

Please provide any additional information below.

The problem stems from the fact that btSequentialImpulseConstraintSolver does 
not provide option to randomize non-contact constraints, if support for this is 
added (patch attached) and randomize constraints is enabled the system behaves 
as expected.

Note that the ODE quickstep solver provides this as an option and was found to 
exhibit the same problems when used with bullet and constraint randomization 
disabled.

See thread here:

http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?t=7672

Original issue reported on code.google.com by peter.kyme on 8 Dec 2011 at 5:14

Attachments:

GoogleCodeExporter commented 9 years ago 
Thanks for the patch, it is applied in latest trunk:

http://code.google.com/p/bullet/source/detail?r=2467

Original comment by erwin.coumans on 14 Dec 2011 at 9:06