Hi,
I am using Irrlicht and bullet physics for developing applications. I have mesh objects of
btTriangleMesh* triangleMesh and i convert it into
btConvexTriangleMeshShape* MeshShape = new btConvexTriangleMeshShape(triangleMesh);
btCollisionShape *Shape = MeshShape ;
as collision shapes.
1. In my application there is i need one fixed constraint between two bodis and one of it is also linked to another body(3rd body).
how i can make a fixed joint in bullet physics?
2. How i can find the axis of the 3rd body and rotate the fourth body in the basis of 3rd one considering it as also fixed.
I made it by using hingeconstraint in bullet physics but the pivot point is not correct....how it is possible ...
please help me...
Fixed joint in bullet physics
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Re: Fixed joint in bullet physics
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1. In my application there is i need one fixed constraint between two bodis and one of it is also linked to another body(3rd body).
how i can make a fixed joint in bullet physics?
Position/orientation of pivots can be easily set within a modeler, such as Blender. It can directly export constraint and rigid bodies to COLLADA.2. How i can find the axis of the 3rd body and rotate the fourth body in the basis of 3rd one considering it as also fixed.
I made it by using hingeconstraint in bullet physics but the pivot point is not correct....how it is possible ...
Alternatively, describe the object and pivot transform all in world space, and then transform the pivot in local space, using the inverse world transform of the object:
Code: Select all
btVector3 pivotLocalSpace = rigidbody->getCenterOfMassTransform().inverse()(pivotWorldSpace);
Erwin
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Re: Fixed joint in bullet physics
Hi,
I'm having the same issue, and the reason is that I have a system where the user can add/remove
objects from some base body that propel it forward (like a jet engine) it'd be a major hassle to insert
and merge collisionshapes at every (dis)connect, much easier to connect objects via fixed constraints.
BUT the constraints are quite 'soft' even when lin and ang min/max values are all zero. is there any way
to make a fixed constraint perfectly rigid (without resorting to making a compoundShape) ?
thanks,
Jonathan
I'm having the same issue, and the reason is that I have a system where the user can add/remove
objects from some base body that propel it forward (like a jet engine) it'd be a major hassle to insert
and merge collisionshapes at every (dis)connect, much easier to connect objects via fixed constraints.
BUT the constraints are quite 'soft' even when lin and ang min/max values are all zero. is there any way
to make a fixed constraint perfectly rigid (without resorting to making a compoundShape) ?
thanks,
Jonathan
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Re: Fixed joint in bullet physics
Unfortunately the only way is btCompoundShape. The Bullet/Demos/FractureDemo shows how to glue/break objects.
I'll try to make it easier to add glue/breakable compounds in a future SDK.
Fixed constraints will not be very rigid, it is a limitation of the current iterative constraint solver.
Thanks,
Erwin
I'll try to make it easier to add glue/breakable compounds in a future SDK.
Fixed constraints will not be very rigid, it is a limitation of the current iterative constraint solver.
Thanks,
Erwin
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Re: Fixed joint in bullet physics
thanks for the quick reply, Erwin !
Ill have a look at the demo.
Ill have a look at the demo.
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Re: Fixed joint in bullet physics
by the way, if I want to *maximize* stiffness of a bt6DOFGenericConstraint for instance,
how do I access the relevant parameters ?
thanks,
J
how do I access the relevant parameters ?
thanks,
J
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Re: Fixed joint in bullet physics
Look into Yann's post in
http://bulletphysics.org/Bullet/phpBB3/ ... f=9&t=6792
check out the ERP and CFM parameters in a constraint solver
http://bulletphysics.org/Bullet/phpBB3/ ... f=9&t=6792
check out the ERP and CFM parameters in a constraint solver