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separate spinning friction (torsional friction around contact normal) from

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rolling friction (orthogonal to contact normal)
This commit is contained in:
Erwin Coumans
2016-09-16 00:04:33 +01:00
parent 4d6a95017e
commit 1d88cf71e4
11 changed files with 67 additions and 9 deletions
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1
src/BulletCollision/CollisionDispatch/btCollisionObject.cpp
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@@ -33,6 +33,7 @@ btCollisionObject::btCollisionObject()
m_friction(btScalar(0.5)),
m_restitution(btScalar(0.)),
m_rollingFriction(0.0f),
m_spinningFriction(0.f),
m_contactDamping(.1),
m_contactStiffness(1e4),
m_internalType(CO_COLLISION_OBJECT),

13
src/BulletCollision/CollisionDispatch/btCollisionObject.h
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@@ -85,7 +85,8 @@ protected:
btScalar m_friction;
btScalar m_restitution;
btScalar m_rollingFriction;
btScalar m_rollingFriction;//torsional friction orthogonal to contact normal (useful to stop spheres rolling forever)
btScalar m_spinningFriction; // torsional friction around the contact normal (useful for grasping)
btScalar m_contactDamping;
btScalar m_contactStiffness;
@@ -323,7 +324,15 @@ public:
{
return m_rollingFriction;
}
void setSpinningFriction(btScalar frict)
{
m_updateRevision++;
m_spinningFriction = frict;
}
btScalar getSpinningFriction() const
{
return m_spinningFriction;
}
void setContactStiffnessAndDamping(btScalar stiffness, btScalar damping)
{
m_updateRevision++;

12
src/BulletCollision/CollisionDispatch/btManifoldResult.cpp
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@@ -24,7 +24,6 @@ ContactAddedCallback gContactAddedCallback=0;
///User can override this material combiner by implementing gContactAddedCallback and setting body0->m_collisionFlags |= btCollisionObject::customMaterialCallback;
btScalar btManifoldResult::calculateCombinedRollingFriction(const btCollisionObject* body0,const btCollisionObject* body1)
{
btScalar friction = body0->getRollingFriction() * body1->getFriction() + body1->getRollingFriction() * body0->getFriction();
@@ -38,6 +37,17 @@ btScalar btManifoldResult::calculateCombinedRollingFriction(const btCollisionObj
}
btScalar btManifoldResult::calculateCombinedSpinningFriction(const btCollisionObject* body0,const btCollisionObject* body1)
{
btScalar friction = body0->getSpinningFriction() * body1->getFriction() + body1->getSpinningFriction() * body0->getFriction();
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;
btScalar btManifoldResult::calculateCombinedFriction(const btCollisionObject* body0,const btCollisionObject* body1)

3
src/BulletCollision/CollisionDispatch/btManifoldResult.h
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@@ -146,7 +146,8 @@ public:
static btScalar calculateCombinedRestitution(const btCollisionObject* body0,const btCollisionObject* body1);
static btScalar calculateCombinedFriction(const btCollisionObject* body0,const btCollisionObject* body1);
static btScalar calculateCombinedRollingFriction(const btCollisionObject* body0,const btCollisionObject* body1);
static btScalar calculateCombinedContactDamping(const btCollisionObject* body0,const btCollisionObject* body1);
static btScalar calculateCombinedSpinningFriction(const btCollisionObject* body0,const btCollisionObject* body1);
static btScalar calculateCombinedContactDamping(const btCollisionObject* body0,const btCollisionObject* body1);
static btScalar calculateCombinedContactStiffness(const btCollisionObject* body0,const btCollisionObject* body1);
};

8
src/BulletCollision/NarrowPhaseCollision/btManifoldPoint.h
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@@ -72,7 +72,8 @@ class btManifoldPoint
m_distance1( distance ),
m_combinedFriction(btScalar(0.)),
m_combinedRollingFriction(btScalar(0.)),
m_combinedRestitution(btScalar(0.)),
m_combinedSpinningFriction(btScalar(0.)),
m_combinedRestitution(btScalar(0.)),
m_userPersistentData(0),
m_contactPointFlags(0),
m_appliedImpulse(0.f),
@@ -99,8 +100,9 @@ class btManifoldPoint
btScalar m_distance1;
btScalar m_combinedFriction;
btScalar m_combinedRollingFriction;
btScalar m_combinedRestitution;
btScalar m_combinedRollingFriction;//torsional friction orthogonal to contact normal, useful to make spheres stop rolling forever
btScalar m_combinedSpinningFriction;//torsional friction around contact normal, useful for grasping objects
btScalar m_combinedRestitution;
//BP mod, store contact triangles.
int m_partId0;