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Code Issues Releases Wiki Activity

friction is working now

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This commit is contained in:
jingyuc 2021-08-25 16:38:57 -04:00
parent 52abe35e41
commit 6a87310d3c
4 changed files with 56 additions and 54 deletions
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12
examples/ReducedDeformableDemo/FreeFall.cpp
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@ -56,10 +56,10 @@ public:
void resetCamera()
{
float dist = 10;
float dist = 20;
float pitch = -30;
float yaw = 60;
float targetPos[3] = {0, 6, 0};
float yaw = 125;
float targetPos[3] = {-2, 0, 2};
m_guiHelper->resetCamera(dist, yaw, pitch, targetPos[0], targetPos[1], targetPos[2]);
}
@ -189,13 +189,13 @@ void FreeFall::initPhysics()
// create a static rigid box as the ground
{
// btBoxShape* groundShape = createBoxShape(btVector3(btScalar(50), btScalar(50), btScalar(50)));
btBoxShape* groundShape = createBoxShape(btVector3(btScalar(10), btScalar(10), btScalar(10)));
btBoxShape* groundShape = createBoxShape(btVector3(btScalar(10), btScalar(2), btScalar(10)));
m_collisionShapes.push_back(groundShape);
btTransform groundTransform;
groundTransform.setIdentity();
groundTransform.setRotation(btQuaternion(btVector3(1, 0, 0), SIMD_PI / 6.0));
groundTransform.setOrigin(btVector3(0, -10, 2));
// groundTransform.setRotation(btQuaternion(btVector3(1, 0, 0), SIMD_PI / 6.0));
groundTransform.setOrigin(btVector3(0, 0, 0));
// groundTransform.setOrigin(btVector3(0, 0, 6));
// groundTransform.setOrigin(btVector3(0, -50, 0));
{

93
src/BulletSoftBody/BulletReducedSoftBody/btReducedDeformableContactConstraint.cpp
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@ -51,22 +51,22 @@ btReducedDeformableRigidContactConstraint::btReducedDeformableRigidContactConstr
{
m_appliedNormalImpulse = 0;
m_appliedTangentImpulse = 0;
m_impulseFactorNormal = 0;
m_impulseFactorTangent = 0;
m_rhs = 0;
m_cfm = 0;
m_erp = btScalar(0.2);
m_friction = btScalar(0.5);
m_friction = btScalar(0.3);
m_contactNormalA = c.m_cti.m_normal;
m_contactNormalB = -c.m_cti.m_normal;
m_impulseFactor = c.m_c0;
m_normalImpulseFactor = (m_impulseFactor * m_contactNormalA).dot(m_contactNormalA);
m_tangentImpulseFactor = 0;
}
btScalar btReducedDeformableRigidContactConstraint::solveConstraint(const btContactSolverInfo& infoGlobal)
{
btVector3 deltaVa = getVa() - m_bufferVelocityA;
btVector3 Va = getVa();
btVector3 deltaVa = Va - m_bufferVelocityA;
btVector3 deltaVb = getDeltaVb();
std::cout << "deltaVa: " << deltaVa[0] << '\t' << deltaVa[1] << '\t' << deltaVa[2] << '\n';
std::cout << "deltaVb: " << deltaVb[0] << '\t' << deltaVb[1] << '\t' << deltaVb[2] << '\n';
@ -100,55 +100,55 @@ btScalar btReducedDeformableRigidContactConstraint::solveConstraint(const btCont
residualSquare *= residualSquare;
// use Coulomb friction (based on delta velocity, |dv_t| = |dv_n * friction|)
btScalar deltaImpulse_tangent = m_friction * deltaImpulse;
if (m_appliedNormalImpulse > 0)
// apply Coulomb friction (based on delta velocity, |dv_t| = |dv_n * friction|)
btScalar deltaImpulse_tangent = 0;
{
// trial velocity change
// deltaImpulse_tangent = m_friction * deltaImpulse;
// btScalar deltaV_tangent_trial = deltaImpulse_tangent * m_impulseFactorTangent;
btScalar total_deltaV_rel_normal = m_appliedNormalImpulse * m_normalImpulseFactor;
btScalar deltaV_tangent_trial = m_friction * total_deltaV_rel_normal;
// initial relative tangential veloity magnitude
btScalar v_rel_tangent = abs((Va - getVb()).dot(m_contactTangent));
// if the trial velocity change is greater than the current tangential relative velocity
if (deltaV_tangent_trial > v_rel_tangent)
{
deltaImpulse_tangent = v_rel_tangent / m_tangentImpulseFactor;
}
else
{
deltaImpulse_tangent = deltaV_tangent_trial / m_tangentImpulseFactor;
}
btScalar sum = m_appliedTangentImpulse + deltaImpulse_tangent;
if (sum > m_appliedNormalImpulse * m_friction)
btScalar lower_limit = - m_appliedNormalImpulse * m_friction;
btScalar upper_limit = m_appliedNormalImpulse * m_friction;
if (sum > upper_limit)
{
deltaImpulse_tangent = upper_limit - m_appliedTangentImpulse;
m_appliedTangentImpulse = upper_limit;
}
else if (sum < lower_limit)
{
deltaImpulse_tangent = lower_limit - m_appliedTangentImpulse;
m_appliedTangentImpulse = lower_limit;
}
else
{
sum = m_appliedNormalImpulse * m_friction;
m_appliedTangentImpulse = sum;
}
else if (sum < - m_appliedNormalImpulse * m_friction)
{
sum = -m_appliedNormalImpulse * m_friction;
m_appliedTangentImpulse = sum;
}
deltaImpulse_tangent = sum - m_appliedTangentImpulse;
std::cout << "deltaImpulse_tangent: " << deltaImpulse_tangent << '\n';
}
// // friction correction
// btScalar delta_v_rel_normal = v_rel_normal;
// btScalar delta_v_rel_tangent = m_contact->m_c3 * v_rel_normal;
// // btScalar delta_v_rel_tangent = 0.3 * v_rel_normal;
// btVector3 impulse_tangent(0, 0, 0);
// if (v_rel_tangent.norm() < delta_v_rel_tangent)
// {
// // the object should be static
// impulse_tangent = m_contact->m_c0 * (-v_rel_tangent);
// }
// else
// {
// // apply friction
// impulse_tangent = m_contact->m_c0 * (-v_rel_tangent.safeNormalize() * delta_v_rel_tangent);
// std::cout << "friction called\n";
// }
// get the total impulse vector
btVector3 impulse_normal = deltaImpulse * m_contactNormalA;
btVector3 impulse_tangent = -deltaImpulse_tangent * m_contactTangent;
btVector3 impulse = impulse_normal + impulse_tangent;
// btVector3 impulse_dir = impulse_tangent;
// impulse_dir.safeNormalize();
// std::cout << "impulse direct: " << impulse_dir[0] << '\t' << impulse_dir[1] << '\t' << impulse_dir[2] << '\n';
applyImpulse(impulse);
// applyImpulse(impulse); // TODO: apply impulse?
// apply impulse to the rigid/multibodies involved and change their velocities
// if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY)
// {
@ -202,11 +202,14 @@ void btReducedDeformableNodeRigidContactConstraint::warmStarting()
m_bufferVelocityB = vb;
// we define the (+) direction of errors to be the outward surface normal of the rigid object
btVector3 v_rel = va - vb;
// get tangent direction
m_contactTangent = -(v_rel / v_rel.safeNorm() - m_contactNormalA);
btVector3 v_rel = vb - va;
// get tangent direction of the relative velocity
m_contactTangent = (v_rel - v_rel.dot(m_contactNormalA) * m_contactNormalA).safeNormalize();
btScalar velocity_error = -btDot(v_rel, m_contactNormalA); // magnitude of relative velocity
// tangent impulse factor
m_tangentImpulseFactor = (m_impulseFactor * m_contactTangent).dot(m_contactTangent);
btScalar velocity_error = btDot(v_rel, m_contactNormalA); // magnitude of relative velocity
btScalar position_error = 0;
if (m_penetration > 0)
{
@ -215,7 +218,7 @@ void btReducedDeformableNodeRigidContactConstraint::warmStarting()
else
{
// add penetration correction vel
position_error = m_penetration * m_erp / m_dt; //TODO: add erp parameter
position_error = m_penetration * m_erp / m_dt;
}
// get the initial estimate of impulse magnitude to be applied
// m_rhs = -velocity_error * m_normalImpulseFactorInv;

3
src/BulletSoftBody/BulletReducedSoftBody/btReducedDeformableContactConstraint.h
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@ -36,9 +36,8 @@ class btReducedDeformableRigidContactConstraint : public btDeformableRigidContac
btScalar m_appliedNormalImpulse;
btScalar m_appliedTangentImpulse;
btScalar m_impulseFactorNormal;
btScalar m_impulseFactorTangent;
btScalar m_normalImpulseFactor;
btScalar m_tangentImpulseFactor;
btScalar m_rhs;
btScalar m_cfm;

2
src/BulletSoftBody/BulletReducedSoftBody/btReducedSoftBody.cpp
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@ -8,7 +8,7 @@
btReducedSoftBody::btReducedSoftBody(btSoftBodyWorldInfo* worldInfo, int node_count, const btVector3* x, const btScalar* m)
: btSoftBody(worldInfo, node_count, x, m)
{
m_rigidOnly = true; //! only use rigid frame to debug
m_rigidOnly = false; //! only use rigid frame to debug
// reduced deformable
m_reducedModel = true;