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improve rolling friction using anisotropic direction, to avoid resting in an instable position

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(for implicit capsule, cylinder and cone shape)
See Bullet/Demos/RollingFrictionDemo for an example
This commit is contained in:
erwin.coumans
2012-09-16 17:01:25 +00:00
parent 26c713423f
commit 22fb7d5c1e
8 changed files with 120 additions and 43 deletions
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16
src/BulletCollision/CollisionDispatch/btCollisionObject.h
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@@ -138,6 +138,13 @@ public:
CO_USER_TYPE=32
};
enum AnisotropicFrictionFlags
{
CF_ANISOTROPIC_FRICTION_DISABLED=0,
CF_ANISOTROPIC_FRICTION = 1,
CF_ANISOTROPIC_ROLLING_FRICTION = 2
};
SIMD_FORCE_INLINE bool mergesSimulationIslands() const
{
///static objects, kinematic and object without contact response don't merge islands
@@ -148,14 +155,15 @@ public:
{
return m_anisotropicFriction;
}
void setAnisotropicFriction(const btVector3& anisotropicFriction)
void setAnisotropicFriction(const btVector3& anisotropicFriction, int frictionMode = CF_ANISOTROPIC_FRICTION)
{
m_anisotropicFriction = anisotropicFriction;
m_hasAnisotropicFriction = (anisotropicFriction[0]!=1.f) || (anisotropicFriction[1]!=1.f) || (anisotropicFriction[2]!=1.f);
bool isUnity = (anisotropicFriction[0]!=1.f) || (anisotropicFriction[1]!=1.f) || (anisotropicFriction[2]!=1.f);
m_hasAnisotropicFriction = isUnity?frictionMode : 0;
}
bool hasAnisotropicFriction() const
bool hasAnisotropicFriction(int frictionMode = CF_ANISOTROPIC_FRICTION) const
{
return m_hasAnisotropicFriction!=0;
return (m_hasAnisotropicFriction&frictionMode)!=0;
}
///the constraint solver can discard solving contacts, if the distance is above this threshold. 0 by default.

8
src/BulletCollision/CollisionShapes/btCapsuleShape.h
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@@ -104,6 +104,14 @@ public:
}
virtual btVector3 getAnisotropicRollingFrictionDirection() const
{
btVector3 aniDir(0,0,0);
aniDir[getUpAxis()]=1;
return aniDir;
}
virtual int calculateSerializeBufferSize() const;
///fills the dataBuffer and returns the struct name (and 0 on failure)

7
src/BulletCollision/CollisionShapes/btCollisionShape.h
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@@ -109,6 +109,13 @@ public:
int getShapeType() const { return m_shapeType; }
///the getAnisotropicRollingFrictionDirection can be used in combination with setAnisotropicFriction
///See Bullet/Demos/RollingFrictionDemo for an example
virtual btVector3 getAnisotropicRollingFrictionDirection() const
{
return btVector3(1,1,1);
}
virtual void setMargin(btScalar margin) = 0;
virtual btScalar getMargin() const = 0;

17
src/BulletCollision/CollisionShapes/btConeShape.h
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@@ -84,6 +84,11 @@ public:
return m_coneIndices[1];
}
virtual btVector3 getAnisotropicRollingFrictionDirection() const
{
return btVector3 (0,1,0);
}
virtual void setLocalScaling(const btVector3& scaling);
};
@@ -93,6 +98,12 @@ class btConeShapeX : public btConeShape
{
public:
btConeShapeX(btScalar radius,btScalar height);
virtual btVector3 getAnisotropicRollingFrictionDirection() const
{
return btVector3 (1,0,0);
}
};
///btConeShapeZ implements a Cone shape, around the Z axis
@@ -100,6 +111,12 @@ class btConeShapeZ : public btConeShape
{
public:
btConeShapeZ(btScalar radius,btScalar height);
virtual btVector3 getAnisotropicRollingFrictionDirection() const
{
return btVector3 (0,0,1);
}
};
#endif //BT_CONE_MINKOWSKI_H

7
src/BulletCollision/CollisionShapes/btCylinderShape.h
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@@ -97,6 +97,13 @@ BT_DECLARE_ALIGNED_ALLOCATOR();
return m_upAxis;
}
virtual btVector3 getAnisotropicRollingFrictionDirection() const
{
btVector3 aniDir(0,0,0);
aniDir[getUpAxis()]=1;
return aniDir;
}
virtual btScalar getRadius() const
{
return getHalfExtentsWithMargin().getX();

37
src/BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.cpp
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@@ -324,12 +324,12 @@ btScalar btSequentialImpulseConstraintSolver::restitutionCurve(btScalar rel_vel,
static void applyAnisotropicFriction(btCollisionObject* colObj,btVector3& frictionDirection);
static void applyAnisotropicFriction(btCollisionObject* colObj,btVector3& frictionDirection)
static void applyAnisotropicFriction(btCollisionObject* colObj,btVector3& frictionDirection, int frictionMode);
static void applyAnisotropicFriction(btCollisionObject* colObj,btVector3& frictionDirection, int frictionMode)
{
if (colObj && colObj->hasAnisotropicFriction())
if (colObj && colObj->hasAnisotropicFriction(frictionMode))
{
// transform to local coordinates
btVector3 loc_lateral = frictionDirection * colObj->getWorldTransform().getBasis();
@@ -807,15 +807,24 @@ void btSequentialImpulseConstraintSolver::convertContact(btPersistentManifold* m
if (relAngVel.length()>infoGlobal.m_singleAxisRollingFrictionThreshold)
{
relAngVel.normalize();
addRollingFrictionConstraint(relAngVel,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
applyAnisotropicFriction(colObj0,relAngVel,btCollisionObject::CF_ANISOTROPIC_ROLLING_FRICTION);
applyAnisotropicFriction(colObj1,relAngVel,btCollisionObject::CF_ANISOTROPIC_ROLLING_FRICTION);
if (relAngVel.length()>0.001)
addRollingFrictionConstraint(relAngVel,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
} else
{
addRollingFrictionConstraint(cp.m_normalWorldOnB,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
btVector3 axis0,axis1;
btPlaneSpace1(cp.m_normalWorldOnB,axis0,axis1);
addRollingFrictionConstraint(axis0,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
addRollingFrictionConstraint(axis1,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
applyAnisotropicFriction(colObj0,axis0,btCollisionObject::CF_ANISOTROPIC_ROLLING_FRICTION);
applyAnisotropicFriction(colObj1,axis0,btCollisionObject::CF_ANISOTROPIC_ROLLING_FRICTION);
applyAnisotropicFriction(colObj0,axis1,btCollisionObject::CF_ANISOTROPIC_ROLLING_FRICTION);
applyAnisotropicFriction(colObj1,axis1,btCollisionObject::CF_ANISOTROPIC_ROLLING_FRICTION);
if (axis0.length()>0.001)
addRollingFrictionConstraint(axis0,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
if (axis1.length()>0.001)
addRollingFrictionConstraint(axis1,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
}
}
@@ -834,14 +843,14 @@ void btSequentialImpulseConstraintSolver::convertContact(btPersistentManifold* m
{
cp.m_lateralFrictionDir2 = cp.m_lateralFrictionDir1.cross(cp.m_normalWorldOnB);
cp.m_lateralFrictionDir2.normalize();//??
applyAnisotropicFriction(colObj0,cp.m_lateralFrictionDir2);
applyAnisotropicFriction(colObj1,cp.m_lateralFrictionDir2);
applyAnisotropicFriction(colObj0,cp.m_lateralFrictionDir2,btCollisionObject::CF_ANISOTROPIC_FRICTION);
applyAnisotropicFriction(colObj1,cp.m_lateralFrictionDir2,btCollisionObject::CF_ANISOTROPIC_FRICTION);
addFrictionConstraint(cp.m_lateralFrictionDir2,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
}
applyAnisotropicFriction(colObj0,cp.m_lateralFrictionDir1);
applyAnisotropicFriction(colObj1,cp.m_lateralFrictionDir1);
applyAnisotropicFriction(colObj0,cp.m_lateralFrictionDir1,btCollisionObject::CF_ANISOTROPIC_FRICTION);
applyAnisotropicFriction(colObj1,cp.m_lateralFrictionDir1,btCollisionObject::CF_ANISOTROPIC_FRICTION);
addFrictionConstraint(cp.m_lateralFrictionDir1,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
@@ -853,13 +862,13 @@ void btSequentialImpulseConstraintSolver::convertContact(btPersistentManifold* m
if ((infoGlobal.m_solverMode & SOLVER_USE_2_FRICTION_DIRECTIONS))
{
applyAnisotropicFriction(colObj0,cp.m_lateralFrictionDir2);
applyAnisotropicFriction(colObj1,cp.m_lateralFrictionDir2);
applyAnisotropicFriction(colObj0,cp.m_lateralFrictionDir2,btCollisionObject::CF_ANISOTROPIC_FRICTION);
applyAnisotropicFriction(colObj1,cp.m_lateralFrictionDir2,btCollisionObject::CF_ANISOTROPIC_FRICTION);
addFrictionConstraint(cp.m_lateralFrictionDir2,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);
}
applyAnisotropicFriction(colObj0,cp.m_lateralFrictionDir1);
applyAnisotropicFriction(colObj1,cp.m_lateralFrictionDir1);
applyAnisotropicFriction(colObj0,cp.m_lateralFrictionDir1,btCollisionObject::CF_ANISOTROPIC_FRICTION);
applyAnisotropicFriction(colObj1,cp.m_lateralFrictionDir1,btCollisionObject::CF_ANISOTROPIC_FRICTION);
addFrictionConstraint(cp.m_lateralFrictionDir1,solverBodyIdA,solverBodyIdB,frictionIndex,cp,rel_pos1,rel_pos2,colObj0,colObj1, relaxation);