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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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68
Demos/RollingFrictionDemo/RollingFrictionDemo.cpp
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@@ -171,9 +171,21 @@ void RollingFrictionDemo::initPhysics()
{
//create a few dynamic rigidbodies
// Re-using the same collision is better for memory usage and performance
btCollisionShape* colShape = new btSphereShape(btScalar(1.));
m_collisionShapes.push_back(colShape);
#define NUM_SHAPES 10
btCollisionShape* colShapes[NUM_SHAPES] = {
new btSphereShape(btScalar(1.)),
new btCapsuleShape(0.5,1),
new btCapsuleShapeX(0.5,1),
new btCapsuleShapeZ(0.5,1),
new btConeShape(0.5,1),
new btConeShapeX(0.5,1),
new btConeShapeZ(0.5,1),
new btCylinderShape(btVector3(0.5,1,0.1)),
new btCylinderShapeX(btVector3(1,0.5,0.1)),
new btCylinderShapeZ(btVector3(0.5,0.5,1)),
};
for (int i=0;i<NUM_SHAPES;i++)
m_collisionShapes.push_back(colShapes[i]);
/// Create Dynamic Objects
btTransform startTransform;
@@ -182,36 +194,44 @@ void RollingFrictionDemo::initPhysics()
btScalar mass(1.f);
//rigidbody is dynamic if and only if mass is non zero, otherwise static
bool isDynamic = (mass != 0.f);
btVector3 localInertia(0,0,0);
if (isDynamic)
colShape->calculateLocalInertia(mass,localInertia);
float start_x = START_POS_X - ARRAY_SIZE_X/2;
float start_y = START_POS_Y;
float start_z = START_POS_Z - ARRAY_SIZE_Z/2;
for (int k=0;k<ARRAY_SIZE_Y;k++)
{
for (int i=0;i<ARRAY_SIZE_X;i++)
int shapeIndex = 0;
for (int k=0;k<ARRAY_SIZE_Y;k++)
{
for(int j = 0;j<ARRAY_SIZE_Z;j++)
for (int i=0;i<ARRAY_SIZE_X;i++)
{
startTransform.setOrigin(SCALING*btVector3(
btScalar(2.0*i + start_x),
btScalar(20+2.0*k + start_y),
btScalar(2.0*j + start_z)));
for(int j = 0;j<ARRAY_SIZE_Z;j++)
{
startTransform.setOrigin(SCALING*btVector3(
btScalar(2.0*i + start_x),
btScalar(20+2.0*k + start_y),
btScalar(2.0*j + start_z)));
//using motionstate is recommended, it provides interpolation capabilities, and only synchronizes 'active' objects
btDefaultMotionState* myMotionState = new btDefaultMotionState(startTransform);
btRigidBody::btRigidBodyConstructionInfo rbInfo(mass,myMotionState,colShape,localInertia);
btRigidBody* body = new btRigidBody(rbInfo);
body->setFriction(1.f);
body->setRollingFriction(.3);
m_dynamicsWorld->addRigidBody(body);
shapeIndex++;
btCollisionShape* colShape = colShapes[shapeIndex%NUM_SHAPES];
bool isDynamic = (mass != 0.f);
btVector3 localInertia(0,0,0);
if (isDynamic)
colShape->calculateLocalInertia(mass,localInertia);
//using motionstate is recommended, it provides interpolation capabilities, and only synchronizes 'active' objects
btDefaultMotionState* myMotionState = new btDefaultMotionState(startTransform);
btRigidBody::btRigidBodyConstructionInfo rbInfo(mass,myMotionState,colShape,localInertia);
btRigidBody* body = new btRigidBody(rbInfo);
body->setFriction(1.f);
body->setRollingFriction(.3);
body->setAnisotropicFriction(colShape->getAnisotropicRollingFrictionDirection(),btCollisionObject::CF_ANISOTROPIC_ROLLING_FRICTION);
m_dynamicsWorld->addRigidBody(body);
}
}
}
}