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implemented rolling friction, using a contact constraint. Useful to get rolling spheres to rest, even on a slightly sloped plane.

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See http://www.youtube.com/watch?v=RV7sBAsKu4M and Bullet/Demos/RollingFrictionDemo
Fixes in FractureDemo (mouse picking constraint needs to be removed, otherwise constraint solver crashes/asserts)
This commit is contained in:
erwin.coumans
2012-09-15 06:52:17 +00:00
parent 54744b6ab9
commit 7eebb79ced
14 changed files with 263 additions and 44 deletions
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19
src/BulletCollision/CollisionDispatch/btManifoldResult.cpp
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@@ -22,6 +22,23 @@ subject to the following restrictions:
///This is to allow MaterialCombiner/Custom Friction/Restitution values
ContactAddedCallback gContactAddedCallback=0;
///User can override this material combiner by implementing gContactAddedCallback and setting body0->m_collisionFlags |= btCollisionObject::customMaterialCallback;
inline btScalar calculateCombinedRollingFriction(const btCollisionObject* body0,const btCollisionObject* body1)
{
btScalar friction = body0->getRollingFriction() * body1->getRollingFriction();
const btScalar MAX_FRICTION = btScalar(10.);
if (friction < -MAX_FRICTION)
friction = -MAX_FRICTION;
if (friction > MAX_FRICTION)
friction = MAX_FRICTION;
return friction;
}
///User can override this material combiner by implementing gContactAddedCallback and setting body0->m_collisionFlags |= btCollisionObject::customMaterialCallback;
inline btScalar calculateCombinedFriction(const btCollisionObject* body0,const btCollisionObject* body1)
{
@@ -91,7 +108,7 @@ void btManifoldResult::addContactPoint(const btVector3& normalOnBInWorld,const b
newPt.m_combinedFriction = calculateCombinedFriction(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
newPt.m_combinedRestitution = calculateCombinedRestitution(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
newPt.m_combinedRollingFriction = calculateCombinedRollingFriction(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
btPlaneSpace1(newPt.m_normalWorldOnB,newPt.m_lateralFrictionDir1,newPt.m_lateralFrictionDir2);