diff options
author | Xuchen Han <xuchenhan@xuchenhan-macbookpro.roam.corp.google.com> | 2019-07-18 09:16:01 -0700 |
---|---|---|
committer | Xuchen Han <xuchenhan@xuchenhan-macbookpro.roam.corp.google.com> | 2019-08-02 13:12:51 -0700 |
commit | 3430192db798c773036d247a460da520d0c26762 (patch) | |
tree | 37c6c3cdf545820577cb0ea68abfcfc062bc64da | |
parent | 7846dd38dd5172d3b2876a95fa4a515755195668 (diff) | |
download | bullet3-3430192db798c773036d247a460da520d0c26762.tar.gz |
reformulate friction
-rw-r--r-- | src/BulletSoftBody/btBackwardEulerObjective.cpp | 2 | ||||
-rw-r--r-- | src/BulletSoftBody/btCGProjection.h | 10 | ||||
-rw-r--r-- | src/BulletSoftBody/btContactProjection.cpp | 51 | ||||
-rw-r--r-- | src/BulletSoftBody/btContactProjection.h | 4 |
4 files changed, 36 insertions, 31 deletions
diff --git a/src/BulletSoftBody/btBackwardEulerObjective.cpp b/src/BulletSoftBody/btBackwardEulerObjective.cpp index 3f27df5a9..9174107ba 100644 --- a/src/BulletSoftBody/btBackwardEulerObjective.cpp +++ b/src/BulletSoftBody/btBackwardEulerObjective.cpp @@ -8,7 +8,7 @@ #include "btBackwardEulerObjective.h" btBackwardEulerObjective::btBackwardEulerObjective(btAlignedObjectArray<btSoftBody *>& softBodies, const TVStack& backup_v) -: cg(20) +: cg(10) , m_softBodies(softBodies) , projection(m_softBodies, m_dt) , m_backupVelocity(backup_v) diff --git a/src/BulletSoftBody/btCGProjection.h b/src/BulletSoftBody/btCGProjection.h index a00fe384b..46979c8f0 100644 --- a/src/BulletSoftBody/btCGProjection.h +++ b/src/BulletSoftBody/btCGProjection.h @@ -43,22 +43,23 @@ struct Friction btAlignedObjectArray<btScalar> m_impulse; btAlignedObjectArray<btScalar> m_dv; btAlignedObjectArray<btVector3> m_direction; + btAlignedObjectArray<btVector3> m_direction_prev; btAlignedObjectArray<bool> m_static_prev; btAlignedObjectArray<btScalar> m_impulse_prev; btAlignedObjectArray<btScalar> m_dv_prev; - btAlignedObjectArray<btVector3> m_direction_prev; btAlignedObjectArray<bool> m_released; - btAlignedObjectArray<btVector3> m_accumulated_impulse; + btAlignedObjectArray<btScalar> m_accumulated_normal_impulse; + btAlignedObjectArray<btVector3> m_accumulated_tangent_impulse; Friction() { m_static.push_back(false); m_static_prev.push_back(false); - m_direction.push_back(btVector3(0,0,0)); m_direction_prev.push_back(btVector3(0,0,0)); + m_direction.push_back(btVector3(0,0,0)); m_impulse.push_back(0); m_impulse_prev.push_back(0); @@ -66,7 +67,8 @@ struct Friction m_dv.push_back(0); m_dv_prev.push_back(0); - m_accumulated_impulse.push_back(btVector3(0,0,0)); + m_accumulated_normal_impulse.push_back(0); + m_accumulated_tangent_impulse.push_back(btVector3(0,0,0)); m_released.push_back(false); } }; diff --git a/src/BulletSoftBody/btContactProjection.cpp b/src/BulletSoftBody/btContactProjection.cpp index 3250e010b..041792d08 100644 --- a/src/BulletSoftBody/btContactProjection.cpp +++ b/src/BulletSoftBody/btContactProjection.cpp @@ -11,7 +11,7 @@ void btContactProjection::update(const TVStack& dv, const TVStack& backupVelocity) { ///solve rigid body constraints - m_world->getSolverInfo().m_numIterations = 5; + m_world->getSolverInfo().m_numIterations = 10; m_world->btMultiBodyDynamicsWorld::solveConstraints(m_world->getSolverInfo()); // loop through constraints to set constrained values @@ -73,43 +73,44 @@ void btContactProjection::update(const TVStack& dv, const TVStack& backupVelocit const btVector3 vr = vb - va; const btScalar dn = btDot(vr, cti.m_normal); btVector3 impulse = c->m_c0 * vr; - const btVector3 impulse_normal = c->m_c0 *(cti.m_normal * dn); - btVector3 impulse_tangent = impulse - impulse_normal; - + const btVector3 impulse_normal = c->m_c0 * (cti.m_normal * dn); + const btVector3 impulse_tangent = impulse - impulse_normal; + btScalar local_tangent_norm = impulse_tangent.norm(); + btVector3 local_tangent_dir = btVector3(0,0,0); + if (local_tangent_norm > SIMD_EPSILON) + local_tangent_dir = impulse_tangent.normalized(); // accumulated impulse on the rb in this and all prev cg iterations - friction.m_accumulated_impulse[j] += impulse; - btScalar accumulated_normal = friction.m_accumulated_impulse[j].dot(cti.m_normal); - btVector3 accumulated_tangent = friction.m_accumulated_impulse[j] - accumulated_normal * cti.m_normal; - + friction.m_accumulated_normal_impulse[j] += impulse_normal.dot(cti.m_normal); + btScalar accumulated_normal = friction.m_accumulated_normal_impulse[j]; + btVector3 tangent = friction.m_accumulated_tangent_impulse[j] + impulse_tangent; + btScalar tangent_norm = tangent.norm(); // start friction handling // copy old data - friction.m_direction_prev[j] = friction.m_direction[j]; friction.m_impulse_prev[j] = friction.m_impulse[j]; friction.m_dv_prev[j] = friction.m_dv[j]; friction.m_static_prev[j] = friction.m_static[j]; - if (accumulated_normal < 0 && accumulated_tangent.norm() > SIMD_EPSILON) + if (accumulated_normal < 0 && tangent_norm > SIMD_EPSILON) { - + friction.m_direction[j] = -local_tangent_dir; btScalar compare1 = -accumulated_normal*c->m_c3; - btScalar compare2 = accumulated_tangent.norm(); + btScalar compare2 = tangent_norm; // do not allow switching from static friction to dynamic friction // it causes cg to explode - if (-accumulated_normal*c->m_c3 < accumulated_tangent.norm() && friction.m_static_prev[j] == false && friction.m_released[j] == false) + if (-accumulated_normal*c->m_c3 < tangent_norm && friction.m_static_prev[j] == false && friction.m_released[j] == false) { friction.m_static[j] = false; friction.m_impulse[j] = -accumulated_normal*c->m_c3; - friction.m_dv[j] = -accumulated_normal*c->m_c3 *c->m_c2/m_dt ; + friction.m_dv[j] = 0; + impulse = impulse_normal + (friction.m_impulse_prev[j] * friction.m_direction_prev[j])-(friction.m_impulse[j] * friction.m_direction[j]); } else { friction.m_static[j] = true; - friction.m_impulse[j] = accumulated_tangent.norm(); - friction.m_dv[j] = accumulated_tangent.norm() * c->m_c2/m_dt; + friction.m_impulse[j] = 0; + friction.m_dv[j] = local_tangent_norm * c->m_c2/m_dt; + impulse = impulse_normal + impulse_tangent; } - - const btVector3 tangent_dir = accumulated_tangent.normalized(); - friction.m_direction[j] = -tangent_dir; } else { @@ -117,9 +118,10 @@ void btContactProjection::update(const TVStack& dv, const TVStack& backupVelocit friction.m_static[j] = false; friction.m_impulse[j] = 0; friction.m_dv[j] = 0; + friction.m_direction[j] = btVector3(0,0,0); + impulse = impulse_normal; } - - friction.m_accumulated_impulse[j] = accumulated_normal * cti.m_normal - friction.m_impulse[j] * friction.m_direction[j]; + friction.m_accumulated_tangent_impulse[j] = -friction.m_impulse[j] * friction.m_direction[j]; if (1) // in the same CG solve, the set of constraits doesn't change // if (dn <= SIMD_EPSILON) { @@ -134,7 +136,7 @@ void btContactProjection::update(const TVStack& dv, const TVStack& backupVelocit // the incremental impulse: // in the normal direction it's the normal component of "impulse" // in the tangent direction it's the difference between the frictional impulse in the iteration and the previous iteration - impulse = impulse_normal + (friction.m_impulse_prev[j] * friction.m_direction_prev[j]) - (friction.m_impulse[j] * friction.m_direction[j]); + impulse = impulse_normal + (friction.m_impulse_prev[j] * friction.m_direction_prev[j])-(friction.m_impulse[j] * friction.m_direction[j]); // impulse = impulse_normal; if (cti.m_colObj->getInternalType() == btCollisionObject::CO_RIGID_BODY) { @@ -145,7 +147,7 @@ void btContactProjection::update(const TVStack& dv, const TVStack& backupVelocit { if (multibodyLinkCol) { - double multiplier = 0.5; + double multiplier = 1; multibodyLinkCol->m_multiBody->applyDeltaVeeMultiDof(deltaV, -impulse.length() * multiplier); } } @@ -273,7 +275,8 @@ void btContactProjection::setConstraintDirections() frictions[j].m_dv_prev.push_back(0); frictions[j].m_static.push_back(false); frictions[j].m_static_prev.push_back(false); - frictions[j].m_accumulated_impulse.push_back(btVector3(0,0,0)); + frictions[j].m_accumulated_normal_impulse.push_back(0); + frictions[j].m_accumulated_tangent_impulse.push_back(btVector3(0,0,0)); frictions[j].m_released.push_back(false); merged = true; break; diff --git a/src/BulletSoftBody/btContactProjection.h b/src/BulletSoftBody/btContactProjection.h index 969745d93..566fd9f92 100644 --- a/src/BulletSoftBody/btContactProjection.h +++ b/src/BulletSoftBody/btContactProjection.h @@ -124,7 +124,7 @@ public: // clear the old constraint if (friction.m_static_prev[j] == true) { - x[i] -= friction.m_direction_prev[j] * friction.m_dv_prev[j]; +// x[i] -= friction.m_direction_prev[j] * friction.m_dv_prev[j]; } // add the new constraint if (friction.m_static[j] == true) @@ -156,7 +156,7 @@ public: // clear the old constraint if (friction.m_static_prev[j] == true) { - x[i] -= friction.m_direction_prev[j] * friction.m_dv_prev[j]; +// x[i] -= friction.m_direction_prev[j] * friction.m_dv_prev[j]; } // add the new constraint if (friction.m_static[j] == true) |