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Diffstat (limited to 'extern/bullet2/BulletDynamics/ConstraintSolver/btConeTwistConstraint.cpp')
| -rw-r--r-- | extern/bullet2/BulletDynamics/ConstraintSolver/btConeTwistConstraint.cpp | 1117 |
1 files changed, 1117 insertions, 0 deletions
diff --git a/extern/bullet2/BulletDynamics/ConstraintSolver/btConeTwistConstraint.cpp b/extern/bullet2/BulletDynamics/ConstraintSolver/btConeTwistConstraint.cpp new file mode 100644 index 00000000000..bf77c495404 --- /dev/null +++ b/extern/bullet2/BulletDynamics/ConstraintSolver/btConeTwistConstraint.cpp @@ -0,0 +1,1117 @@ +/* +Bullet Continuous Collision Detection and Physics Library +btConeTwistConstraint is Copyright (c) 2007 Starbreeze Studios + +This software is provided 'as-is', without any express or implied warranty. +In no event will the authors be held liable for any damages arising from the use of this software. +Permission is granted to anyone to use this software for any purpose, +including commercial applications, and to alter it and redistribute it freely, +subject to the following restrictions: + +1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. +2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. +3. This notice may not be removed or altered from any source distribution. + +Written by: Marcus Hennix +*/ + + +#include "btConeTwistConstraint.h" +#include "BulletDynamics/Dynamics/btRigidBody.h" +#include "LinearMath/btTransformUtil.h" +#include "LinearMath/btMinMax.h" +#include <new> + + + +//#define CONETWIST_USE_OBSOLETE_SOLVER true +#define CONETWIST_USE_OBSOLETE_SOLVER false +#define CONETWIST_DEF_FIX_THRESH btScalar(.05f) + + +SIMD_FORCE_INLINE btScalar computeAngularImpulseDenominator(const btVector3& axis, const btMatrix3x3& invInertiaWorld) +{ + btVector3 vec = axis * invInertiaWorld; + return axis.dot(vec); +} + + + + +btConeTwistConstraint::btConeTwistConstraint(btRigidBody& rbA,btRigidBody& rbB, + const btTransform& rbAFrame,const btTransform& rbBFrame) + :btTypedConstraint(CONETWIST_CONSTRAINT_TYPE, rbA,rbB),m_rbAFrame(rbAFrame),m_rbBFrame(rbBFrame), + m_angularOnly(false), + m_useSolveConstraintObsolete(CONETWIST_USE_OBSOLETE_SOLVER) +{ + init(); +} + +btConeTwistConstraint::btConeTwistConstraint(btRigidBody& rbA,const btTransform& rbAFrame) + :btTypedConstraint(CONETWIST_CONSTRAINT_TYPE,rbA),m_rbAFrame(rbAFrame), + m_angularOnly(false), + m_useSolveConstraintObsolete(CONETWIST_USE_OBSOLETE_SOLVER) +{ + m_rbBFrame = m_rbAFrame; + init(); +} + + +void btConeTwistConstraint::init() +{ + m_angularOnly = false; + m_solveTwistLimit = false; + m_solveSwingLimit = false; + m_bMotorEnabled = false; + m_maxMotorImpulse = btScalar(-1); + + setLimit(btScalar(BT_LARGE_FLOAT), btScalar(BT_LARGE_FLOAT), btScalar(BT_LARGE_FLOAT)); + m_damping = btScalar(0.01); + m_fixThresh = CONETWIST_DEF_FIX_THRESH; + m_flags = 0; + m_linCFM = btScalar(0.f); + m_linERP = btScalar(0.7f); + m_angCFM = btScalar(0.f); +} + + +void btConeTwistConstraint::getInfo1 (btConstraintInfo1* info) +{ + if (m_useSolveConstraintObsolete) + { + info->m_numConstraintRows = 0; + info->nub = 0; + } + else + { + info->m_numConstraintRows = 3; + info->nub = 3; + calcAngleInfo2(m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform(),m_rbA.getInvInertiaTensorWorld(),m_rbB.getInvInertiaTensorWorld()); + if(m_solveSwingLimit) + { + info->m_numConstraintRows++; + info->nub--; + if((m_swingSpan1 < m_fixThresh) && (m_swingSpan2 < m_fixThresh)) + { + info->m_numConstraintRows++; + info->nub--; + } + } + if(m_solveTwistLimit) + { + info->m_numConstraintRows++; + info->nub--; + } + } +} + +void btConeTwistConstraint::getInfo1NonVirtual (btConstraintInfo1* info) +{ + //always reserve 6 rows: object transform is not available on SPU + info->m_numConstraintRows = 6; + info->nub = 0; + +} + + +void btConeTwistConstraint::getInfo2 (btConstraintInfo2* info) +{ + getInfo2NonVirtual(info,m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform(),m_rbA.getInvInertiaTensorWorld(),m_rbB.getInvInertiaTensorWorld()); +} + +void btConeTwistConstraint::getInfo2NonVirtual (btConstraintInfo2* info,const btTransform& transA,const btTransform& transB,const btMatrix3x3& invInertiaWorldA,const btMatrix3x3& invInertiaWorldB) +{ + calcAngleInfo2(transA,transB,invInertiaWorldA,invInertiaWorldB); + + btAssert(!m_useSolveConstraintObsolete); + // set jacobian + info->m_J1linearAxis[0] = 1; + info->m_J1linearAxis[info->rowskip+1] = 1; + info->m_J1linearAxis[2*info->rowskip+2] = 1; + btVector3 a1 = transA.getBasis() * m_rbAFrame.getOrigin(); + { + btVector3* angular0 = (btVector3*)(info->m_J1angularAxis); + btVector3* angular1 = (btVector3*)(info->m_J1angularAxis+info->rowskip); + btVector3* angular2 = (btVector3*)(info->m_J1angularAxis+2*info->rowskip); + btVector3 a1neg = -a1; + a1neg.getSkewSymmetricMatrix(angular0,angular1,angular2); + } + btVector3 a2 = transB.getBasis() * m_rbBFrame.getOrigin(); + { + btVector3* angular0 = (btVector3*)(info->m_J2angularAxis); + btVector3* angular1 = (btVector3*)(info->m_J2angularAxis+info->rowskip); + btVector3* angular2 = (btVector3*)(info->m_J2angularAxis+2*info->rowskip); + a2.getSkewSymmetricMatrix(angular0,angular1,angular2); + } + // set right hand side + btScalar linERP = (m_flags & BT_CONETWIST_FLAGS_LIN_ERP) ? m_linERP : info->erp; + btScalar k = info->fps * linERP; + int j; + for (j=0; j<3; j++) + { + info->m_constraintError[j*info->rowskip] = k * (a2[j] + transB.getOrigin()[j] - a1[j] - transA.getOrigin()[j]); + info->m_lowerLimit[j*info->rowskip] = -SIMD_INFINITY; + info->m_upperLimit[j*info->rowskip] = SIMD_INFINITY; + if(m_flags & BT_CONETWIST_FLAGS_LIN_CFM) + { + info->cfm[j*info->rowskip] = m_linCFM; + } + } + int row = 3; + int srow = row * info->rowskip; + btVector3 ax1; + // angular limits + if(m_solveSwingLimit) + { + btScalar *J1 = info->m_J1angularAxis; + btScalar *J2 = info->m_J2angularAxis; + if((m_swingSpan1 < m_fixThresh) && (m_swingSpan2 < m_fixThresh)) + { + btTransform trA = transA*m_rbAFrame; + btVector3 p = trA.getBasis().getColumn(1); + btVector3 q = trA.getBasis().getColumn(2); + int srow1 = srow + info->rowskip; + J1[srow+0] = p[0]; + J1[srow+1] = p[1]; + J1[srow+2] = p[2]; + J1[srow1+0] = q[0]; + J1[srow1+1] = q[1]; + J1[srow1+2] = q[2]; + J2[srow+0] = -p[0]; + J2[srow+1] = -p[1]; + J2[srow+2] = -p[2]; + J2[srow1+0] = -q[0]; + J2[srow1+1] = -q[1]; + J2[srow1+2] = -q[2]; + btScalar fact = info->fps * m_relaxationFactor; + info->m_constraintError[srow] = fact * m_swingAxis.dot(p); + info->m_constraintError[srow1] = fact * m_swingAxis.dot(q); + info->m_lowerLimit[srow] = -SIMD_INFINITY; + info->m_upperLimit[srow] = SIMD_INFINITY; + info->m_lowerLimit[srow1] = -SIMD_INFINITY; + info->m_upperLimit[srow1] = SIMD_INFINITY; + srow = srow1 + info->rowskip; + } + else + { + ax1 = m_swingAxis * m_relaxationFactor * m_relaxationFactor; + J1[srow+0] = ax1[0]; + J1[srow+1] = ax1[1]; + J1[srow+2] = ax1[2]; + J2[srow+0] = -ax1[0]; + J2[srow+1] = -ax1[1]; + J2[srow+2] = -ax1[2]; + btScalar k = info->fps * m_biasFactor; + + info->m_constraintError[srow] = k * m_swingCorrection; + if(m_flags & BT_CONETWIST_FLAGS_ANG_CFM) + { + info->cfm[srow] = m_angCFM; + } + // m_swingCorrection is always positive or 0 + info->m_lowerLimit[srow] = 0; + info->m_upperLimit[srow] = SIMD_INFINITY; + srow += info->rowskip; + } + } + if(m_solveTwistLimit) + { + ax1 = m_twistAxis * m_relaxationFactor * m_relaxationFactor; + btScalar *J1 = info->m_J1angularAxis; + btScalar *J2 = info->m_J2angularAxis; + J1[srow+0] = ax1[0]; + J1[srow+1] = ax1[1]; + J1[srow+2] = ax1[2]; + J2[srow+0] = -ax1[0]; + J2[srow+1] = -ax1[1]; + J2[srow+2] = -ax1[2]; + btScalar k = info->fps * m_biasFactor; + info->m_constraintError[srow] = k * m_twistCorrection; + if(m_flags & BT_CONETWIST_FLAGS_ANG_CFM) + { + info->cfm[srow] = m_angCFM; + } + if(m_twistSpan > 0.0f) + { + + if(m_twistCorrection > 0.0f) + { + info->m_lowerLimit[srow] = 0; + info->m_upperLimit[srow] = SIMD_INFINITY; + } + else + { + info->m_lowerLimit[srow] = -SIMD_INFINITY; + info->m_upperLimit[srow] = 0; + } + } + else + { + info->m_lowerLimit[srow] = -SIMD_INFINITY; + info->m_upperLimit[srow] = SIMD_INFINITY; + } + srow += info->rowskip; + } +} + + + +void btConeTwistConstraint::buildJacobian() +{ + if (m_useSolveConstraintObsolete) + { + m_appliedImpulse = btScalar(0.); + m_accTwistLimitImpulse = btScalar(0.); + m_accSwingLimitImpulse = btScalar(0.); + m_accMotorImpulse = btVector3(0.,0.,0.); + + if (!m_angularOnly) + { + btVector3 pivotAInW = m_rbA.getCenterOfMassTransform()*m_rbAFrame.getOrigin(); + btVector3 pivotBInW = m_rbB.getCenterOfMassTransform()*m_rbBFrame.getOrigin(); + btVector3 relPos = pivotBInW - pivotAInW; + + btVector3 normal[3]; + if (relPos.length2() > SIMD_EPSILON) + { + normal[0] = relPos.normalized(); + } + else + { + normal[0].setValue(btScalar(1.0),0,0); + } + + btPlaneSpace1(normal[0], normal[1], normal[2]); + + for (int i=0;i<3;i++) + { + new (&m_jac[i]) btJacobianEntry( + m_rbA.getCenterOfMassTransform().getBasis().transpose(), + m_rbB.getCenterOfMassTransform().getBasis().transpose(), + pivotAInW - m_rbA.getCenterOfMassPosition(), + pivotBInW - m_rbB.getCenterOfMassPosition(), + normal[i], + m_rbA.getInvInertiaDiagLocal(), + m_rbA.getInvMass(), + m_rbB.getInvInertiaDiagLocal(), + m_rbB.getInvMass()); + } + } + + calcAngleInfo2(m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform(),m_rbA.getInvInertiaTensorWorld(),m_rbB.getInvInertiaTensorWorld()); + } +} + + + +void btConeTwistConstraint::solveConstraintObsolete(btRigidBody& bodyA,btRigidBody& bodyB,btScalar timeStep) +{ + #ifndef __SPU__ + if (m_useSolveConstraintObsolete) + { + btVector3 pivotAInW = m_rbA.getCenterOfMassTransform()*m_rbAFrame.getOrigin(); + btVector3 pivotBInW = m_rbB.getCenterOfMassTransform()*m_rbBFrame.getOrigin(); + + btScalar tau = btScalar(0.3); + + //linear part + if (!m_angularOnly) + { + btVector3 rel_pos1 = pivotAInW - m_rbA.getCenterOfMassPosition(); + btVector3 rel_pos2 = pivotBInW - m_rbB.getCenterOfMassPosition(); + + btVector3 vel1; + bodyA.internalGetVelocityInLocalPointObsolete(rel_pos1,vel1); + btVector3 vel2; + bodyB.internalGetVelocityInLocalPointObsolete(rel_pos2,vel2); + btVector3 vel = vel1 - vel2; + + for (int i=0;i<3;i++) + { + const btVector3& normal = m_jac[i].m_linearJointAxis; + btScalar jacDiagABInv = btScalar(1.) / m_jac[i].getDiagonal(); + + btScalar rel_vel; + rel_vel = normal.dot(vel); + //positional error (zeroth order error) + btScalar depth = -(pivotAInW - pivotBInW).dot(normal); //this is the error projected on the normal + btScalar impulse = depth*tau/timeStep * jacDiagABInv - rel_vel * jacDiagABInv; + m_appliedImpulse += impulse; + + btVector3 ftorqueAxis1 = rel_pos1.cross(normal); + btVector3 ftorqueAxis2 = rel_pos2.cross(normal); + bodyA.internalApplyImpulse(normal*m_rbA.getInvMass(), m_rbA.getInvInertiaTensorWorld()*ftorqueAxis1,impulse); + bodyB.internalApplyImpulse(normal*m_rbB.getInvMass(), m_rbB.getInvInertiaTensorWorld()*ftorqueAxis2,-impulse); + + } + } + + // apply motor + if (m_bMotorEnabled) + { + // compute current and predicted transforms + btTransform trACur = m_rbA.getCenterOfMassTransform(); + btTransform trBCur = m_rbB.getCenterOfMassTransform(); + btVector3 omegaA; bodyA.internalGetAngularVelocity(omegaA); + btVector3 omegaB; bodyB.internalGetAngularVelocity(omegaB); + btTransform trAPred; trAPred.setIdentity(); + btVector3 zerovec(0,0,0); + btTransformUtil::integrateTransform( + trACur, zerovec, omegaA, timeStep, trAPred); + btTransform trBPred; trBPred.setIdentity(); + btTransformUtil::integrateTransform( + trBCur, zerovec, omegaB, timeStep, trBPred); + + // compute desired transforms in world + btTransform trPose(m_qTarget); + btTransform trABDes = m_rbBFrame * trPose * m_rbAFrame.inverse(); + btTransform trADes = trBPred * trABDes; + btTransform trBDes = trAPred * trABDes.inverse(); + + // compute desired omegas in world + btVector3 omegaADes, omegaBDes; + + btTransformUtil::calculateVelocity(trACur, trADes, timeStep, zerovec, omegaADes); + btTransformUtil::calculateVelocity(trBCur, trBDes, timeStep, zerovec, omegaBDes); + + // compute delta omegas + btVector3 dOmegaA = omegaADes - omegaA; + btVector3 dOmegaB = omegaBDes - omegaB; + + // compute weighted avg axis of dOmega (weighting based on inertias) + btVector3 axisA, axisB; + btScalar kAxisAInv = 0, kAxisBInv = 0; + + if (dOmegaA.length2() > SIMD_EPSILON) + { + axisA = dOmegaA.normalized(); + kAxisAInv = getRigidBodyA().computeAngularImpulseDenominator(axisA); + } + + if (dOmegaB.length2() > SIMD_EPSILON) + { + axisB = dOmegaB.normalized(); + kAxisBInv = getRigidBodyB().computeAngularImpulseDenominator(axisB); + } + + btVector3 avgAxis = kAxisAInv * axisA + kAxisBInv * axisB; + + static bool bDoTorque = true; + if (bDoTorque && avgAxis.length2() > SIMD_EPSILON) + { + avgAxis.normalize(); + kAxisAInv = getRigidBodyA().computeAngularImpulseDenominator(avgAxis); + kAxisBInv = getRigidBodyB().computeAngularImpulseDenominator(avgAxis); + btScalar kInvCombined = kAxisAInv + kAxisBInv; + + btVector3 impulse = (kAxisAInv * dOmegaA - kAxisBInv * dOmegaB) / + (kInvCombined * kInvCombined); + + if (m_maxMotorImpulse >= 0) + { + btScalar fMaxImpulse = m_maxMotorImpulse; + if (m_bNormalizedMotorStrength) + fMaxImpulse = fMaxImpulse/kAxisAInv; + + btVector3 newUnclampedAccImpulse = m_accMotorImpulse + impulse; + btScalar newUnclampedMag = newUnclampedAccImpulse.length(); + if (newUnclampedMag > fMaxImpulse) + { + newUnclampedAccImpulse.normalize(); + newUnclampedAccImpulse *= fMaxImpulse; + impulse = newUnclampedAccImpulse - m_accMotorImpulse; + } + m_accMotorImpulse += impulse; + } + + btScalar impulseMag = impulse.length(); + btVector3 impulseAxis = impulse / impulseMag; + + bodyA.internalApplyImpulse(btVector3(0,0,0), m_rbA.getInvInertiaTensorWorld()*impulseAxis, impulseMag); + bodyB.internalApplyImpulse(btVector3(0,0,0), m_rbB.getInvInertiaTensorWorld()*impulseAxis, -impulseMag); + + } + } + else if (m_damping > SIMD_EPSILON) // no motor: do a little damping + { + btVector3 angVelA; bodyA.internalGetAngularVelocity(angVelA); + btVector3 angVelB; bodyB.internalGetAngularVelocity(angVelB); + btVector3 relVel = angVelB - angVelA; + if (relVel.length2() > SIMD_EPSILON) + { + btVector3 relVelAxis = relVel.normalized(); + btScalar m_kDamping = btScalar(1.) / + (getRigidBodyA().computeAngularImpulseDenominator(relVelAxis) + + getRigidBodyB().computeAngularImpulseDenominator(relVelAxis)); + btVector3 impulse = m_damping * m_kDamping * relVel; + + btScalar impulseMag = impulse.length(); + btVector3 impulseAxis = impulse / impulseMag; + bodyA.internalApplyImpulse(btVector3(0,0,0), m_rbA.getInvInertiaTensorWorld()*impulseAxis, impulseMag); + bodyB.internalApplyImpulse(btVector3(0,0,0), m_rbB.getInvInertiaTensorWorld()*impulseAxis, -impulseMag); + } + } + + // joint limits + { + ///solve angular part + btVector3 angVelA; + bodyA.internalGetAngularVelocity(angVelA); + btVector3 angVelB; + bodyB.internalGetAngularVelocity(angVelB); + + // solve swing limit + if (m_solveSwingLimit) + { + btScalar amplitude = m_swingLimitRatio * m_swingCorrection*m_biasFactor/timeStep; + btScalar relSwingVel = (angVelB - angVelA).dot(m_swingAxis); + if (relSwingVel > 0) + amplitude += m_swingLimitRatio * relSwingVel * m_relaxationFactor; + btScalar impulseMag = amplitude * m_kSwing; + + // Clamp the accumulated impulse + btScalar temp = m_accSwingLimitImpulse; + m_accSwingLimitImpulse = btMax(m_accSwingLimitImpulse + impulseMag, btScalar(0.0) ); + impulseMag = m_accSwingLimitImpulse - temp; + + btVector3 impulse = m_swingAxis * impulseMag; + + // don't let cone response affect twist + // (this can happen since body A's twist doesn't match body B's AND we use an elliptical cone limit) + { + btVector3 impulseTwistCouple = impulse.dot(m_twistAxisA) * m_twistAxisA; + btVector3 impulseNoTwistCouple = impulse - impulseTwistCouple; + impulse = impulseNoTwistCouple; + } + + impulseMag = impulse.length(); + btVector3 noTwistSwingAxis = impulse / impulseMag; + + bodyA.internalApplyImpulse(btVector3(0,0,0), m_rbA.getInvInertiaTensorWorld()*noTwistSwingAxis, impulseMag); + bodyB.internalApplyImpulse(btVector3(0,0,0), m_rbB.getInvInertiaTensorWorld()*noTwistSwingAxis, -impulseMag); + } + + + // solve twist limit + if (m_solveTwistLimit) + { + btScalar amplitude = m_twistLimitRatio * m_twistCorrection*m_biasFactor/timeStep; + btScalar relTwistVel = (angVelB - angVelA).dot( m_twistAxis ); + if (relTwistVel > 0) // only damp when moving towards limit (m_twistAxis flipping is important) + amplitude += m_twistLimitRatio * relTwistVel * m_relaxationFactor; + btScalar impulseMag = amplitude * m_kTwist; + + // Clamp the accumulated impulse + btScalar temp = m_accTwistLimitImpulse; + m_accTwistLimitImpulse = btMax(m_accTwistLimitImpulse + impulseMag, btScalar(0.0) ); + impulseMag = m_accTwistLimitImpulse - temp; + + btVector3 impulse = m_twistAxis * impulseMag; + + bodyA.internalApplyImpulse(btVector3(0,0,0), m_rbA.getInvInertiaTensorWorld()*m_twistAxis,impulseMag); + bodyB.internalApplyImpulse(btVector3(0,0,0), m_rbB.getInvInertiaTensorWorld()*m_twistAxis,-impulseMag); + } + } + } +#else +btAssert(0); +#endif //__SPU__ +} + + + + +void btConeTwistConstraint::updateRHS(btScalar timeStep) +{ + (void)timeStep; + +} + + +#ifndef __SPU__ +void btConeTwistConstraint::calcAngleInfo() +{ + m_swingCorrection = btScalar(0.); + m_twistLimitSign = btScalar(0.); + m_solveTwistLimit = false; + m_solveSwingLimit = false; + + btVector3 b1Axis1,b1Axis2,b1Axis3; + btVector3 b2Axis1,b2Axis2; + + b1Axis1 = getRigidBodyA().getCenterOfMassTransform().getBasis() * this->m_rbAFrame.getBasis().getColumn(0); + b2Axis1 = getRigidBodyB().getCenterOfMassTransform().getBasis() * this->m_rbBFrame.getBasis().getColumn(0); + + btScalar swing1=btScalar(0.),swing2 = btScalar(0.); + + btScalar swx=btScalar(0.),swy = btScalar(0.); + btScalar thresh = btScalar(10.); + btScalar fact; + + // Get Frame into world space + if (m_swingSpan1 >= btScalar(0.05f)) + { + b1Axis2 = getRigidBodyA().getCenterOfMassTransform().getBasis() * this->m_rbAFrame.getBasis().getColumn(1); + swx = b2Axis1.dot(b1Axis1); + swy = b2Axis1.dot(b1Axis2); + swing1 = btAtan2Fast(swy, swx); + fact = (swy*swy + swx*swx) * thresh * thresh; + fact = fact / (fact + btScalar(1.0)); + swing1 *= fact; + } + + if (m_swingSpan2 >= btScalar(0.05f)) + { + b1Axis3 = getRigidBodyA().getCenterOfMassTransform().getBasis() * this->m_rbAFrame.getBasis().getColumn(2); + swx = b2Axis1.dot(b1Axis1); + swy = b2Axis1.dot(b1Axis3); + swing2 = btAtan2Fast(swy, swx); + fact = (swy*swy + swx*swx) * thresh * thresh; + fact = fact / (fact + btScalar(1.0)); + swing2 *= fact; + } + + btScalar RMaxAngle1Sq = 1.0f / (m_swingSpan1*m_swingSpan1); + btScalar RMaxAngle2Sq = 1.0f / (m_swingSpan2*m_swingSpan2); + btScalar EllipseAngle = btFabs(swing1*swing1)* RMaxAngle1Sq + btFabs(swing2*swing2) * RMaxAngle2Sq; + + if (EllipseAngle > 1.0f) + { + m_swingCorrection = EllipseAngle-1.0f; + m_solveSwingLimit = true; + // Calculate necessary axis & factors + m_swingAxis = b2Axis1.cross(b1Axis2* b2Axis1.dot(b1Axis2) + b1Axis3* b2Axis1.dot(b1Axis3)); + m_swingAxis.normalize(); + btScalar swingAxisSign = (b2Axis1.dot(b1Axis1) >= 0.0f) ? 1.0f : -1.0f; + m_swingAxis *= swingAxisSign; + } + + // Twist limits + if (m_twistSpan >= btScalar(0.)) + { + btVector3 b2Axis2 = getRigidBodyB().getCenterOfMassTransform().getBasis() * this->m_rbBFrame.getBasis().getColumn(1); + btQuaternion rotationArc = shortestArcQuat(b2Axis1,b1Axis1); + btVector3 TwistRef = quatRotate(rotationArc,b2Axis2); + btScalar twist = btAtan2Fast( TwistRef.dot(b1Axis3), TwistRef.dot(b1Axis2) ); + m_twistAngle = twist; + +// btScalar lockedFreeFactor = (m_twistSpan > btScalar(0.05f)) ? m_limitSoftness : btScalar(0.); + btScalar lockedFreeFactor = (m_twistSpan > btScalar(0.05f)) ? btScalar(1.0f) : btScalar(0.); + if (twist <= -m_twistSpan*lockedFreeFactor) + { + m_twistCorrection = -(twist + m_twistSpan); + m_solveTwistLimit = true; + m_twistAxis = (b2Axis1 + b1Axis1) * 0.5f; + m_twistAxis.normalize(); + m_twistAxis *= -1.0f; + } + else if (twist > m_twistSpan*lockedFreeFactor) + { + m_twistCorrection = (twist - m_twistSpan); + m_solveTwistLimit = true; + m_twistAxis = (b2Axis1 + b1Axis1) * 0.5f; + m_twistAxis.normalize(); + } + } +} +#endif //__SPU__ + +static btVector3 vTwist(1,0,0); // twist axis in constraint's space + + + +void btConeTwistConstraint::calcAngleInfo2(const btTransform& transA, const btTransform& transB, const btMatrix3x3& invInertiaWorldA,const btMatrix3x3& invInertiaWorldB) +{ + m_swingCorrection = btScalar(0.); + m_twistLimitSign = btScalar(0.); + m_solveTwistLimit = false; + m_solveSwingLimit = false; + // compute rotation of A wrt B (in constraint space) + if (m_bMotorEnabled && (!m_useSolveConstraintObsolete)) + { // it is assumed that setMotorTarget() was alredy called + // and motor target m_qTarget is within constraint limits + // TODO : split rotation to pure swing and pure twist + // compute desired transforms in world + btTransform trPose(m_qTarget); + btTransform trA = transA * m_rbAFrame; + btTransform trB = transB * m_rbBFrame; + btTransform trDeltaAB = trB * trPose * trA.inverse(); + btQuaternion qDeltaAB = trDeltaAB.getRotation(); + btVector3 swingAxis = btVector3(qDeltaAB.x(), qDeltaAB.y(), qDeltaAB.z()); + m_swingAxis = swingAxis; + m_swingAxis.normalize(); + m_swingCorrection = qDeltaAB.getAngle(); + if(!btFuzzyZero(m_swingCorrection)) + { + m_solveSwingLimit = true; + } + return; + } + + + { + // compute rotation of A wrt B (in constraint space) + btQuaternion qA = transA.getRotation() * m_rbAFrame.getRotation(); + btQuaternion qB = transB.getRotation() * m_rbBFrame.getRotation(); + btQuaternion qAB = qB.inverse() * qA; + // split rotation into cone and twist + // (all this is done from B's perspective. Maybe I should be averaging axes...) + btVector3 vConeNoTwist = quatRotate(qAB, vTwist); vConeNoTwist.normalize(); + btQuaternion qABCone = shortestArcQuat(vTwist, vConeNoTwist); qABCone.normalize(); + btQuaternion qABTwist = qABCone.inverse() * qAB; qABTwist.normalize(); + + if (m_swingSpan1 >= m_fixThresh && m_swingSpan2 >= m_fixThresh) + { + btScalar swingAngle, swingLimit = 0; btVector3 swingAxis; + computeConeLimitInfo(qABCone, swingAngle, swingAxis, swingLimit); + + if (swingAngle > swingLimit * m_limitSoftness) + { + m_solveSwingLimit = true; + + // compute limit ratio: 0->1, where + // 0 == beginning of soft limit + // 1 == hard/real limit + m_swingLimitRatio = 1.f; + if (swingAngle < swingLimit && m_limitSoftness < 1.f - SIMD_EPSILON) + { + m_swingLimitRatio = (swingAngle - swingLimit * m_limitSoftness)/ + (swingLimit - swingLimit * m_limitSoftness); + } + + // swing correction tries to get back to soft limit + m_swingCorrection = swingAngle - (swingLimit * m_limitSoftness); + + // adjustment of swing axis (based on ellipse normal) + adjustSwingAxisToUseEllipseNormal(swingAxis); + + // Calculate necessary axis & factors + m_swingAxis = quatRotate(qB, -swingAxis); + + m_twistAxisA.setValue(0,0,0); + + m_kSwing = btScalar(1.) / + (computeAngularImpulseDenominator(m_swingAxis,invInertiaWorldA) + + computeAngularImpulseDenominator(m_swingAxis,invInertiaWorldB)); + } + } + else + { + // you haven't set any limits; + // or you're trying to set at least one of the swing limits too small. (if so, do you really want a conetwist constraint?) + // anyway, we have either hinge or fixed joint + btVector3 ivA = transA.getBasis() * m_rbAFrame.getBasis().getColumn(0); + btVector3 jvA = transA.getBasis() * m_rbAFrame.getBasis().getColumn(1); + btVector3 kvA = transA.getBasis() * m_rbAFrame.getBasis().getColumn(2); + btVector3 ivB = transB.getBasis() * m_rbBFrame.getBasis().getColumn(0); + btVector3 target; + btScalar x = ivB.dot(ivA); + btScalar y = ivB.dot(jvA); + btScalar z = ivB.dot(kvA); + if((m_swingSpan1 < m_fixThresh) && (m_swingSpan2 < m_fixThresh)) + { // fixed. We'll need to add one more row to constraint + if((!btFuzzyZero(y)) || (!(btFuzzyZero(z)))) + { + m_solveSwingLimit = true; + m_swingAxis = -ivB.cross(ivA); + } + } + else + { + if(m_swingSpan1 < m_fixThresh) + { // hinge around Y axis + if(!(btFuzzyZero(y))) + { + m_solveSwingLimit = true; + if(m_swingSpan2 >= m_fixThresh) + { + y = btScalar(0.f); + btScalar span2 = btAtan2(z, x); + if(span2 > m_swingSpan2) + { + x = btCos(m_swingSpan2); + z = btSin(m_swingSpan2); + } + else if(span2 < -m_swingSpan2) + { + x = btCos(m_swingSpan2); + z = -btSin(m_swingSpan2); + } + } + } + } + else + { // hinge around Z axis + if(!btFuzzyZero(z)) + { + m_solveSwingLimit = true; + if(m_swingSpan1 >= m_fixThresh) + { + z = btScalar(0.f); + btScalar span1 = btAtan2(y, x); + if(span1 > m_swingSpan1) + { + x = btCos(m_swingSpan1); + y = btSin(m_swingSpan1); + } + else if(span1 < -m_swingSpan1) + { + x = btCos(m_swingSpan1); + y = -btSin(m_swingSpan1); + } + } + } + } + target[0] = x * ivA[0] + y * jvA[0] + z * kvA[0]; + target[1] = x * ivA[1] + y * jvA[1] + z * kvA[1]; + target[2] = x * ivA[2] + y * jvA[2] + z * kvA[2]; + target.normalize(); + m_swingAxis = -ivB.cross(target); + m_swingCorrection = m_swingAxis.length(); + m_swingAxis.normalize(); + } + } + + if (m_twistSpan >= btScalar(0.f)) + { + btVector3 twistAxis; + computeTwistLimitInfo(qABTwist, m_twistAngle, twistAxis); + + if (m_twistAngle > m_twistSpan*m_limitSoftness) + { + m_solveTwistLimit = true; + + m_twistLimitRatio = 1.f; + if (m_twistAngle < m_twistSpan && m_limitSoftness < 1.f - SIMD_EPSILON) + { + m_twistLimitRatio = (m_twistAngle - m_twistSpan * m_limitSoftness)/ + (m_twistSpan - m_twistSpan * m_limitSoftness); + } + + // twist correction tries to get back to soft limit + m_twistCorrection = m_twistAngle - (m_twistSpan * m_limitSoftness); + + m_twistAxis = quatRotate(qB, -twistAxis); + + m_kTwist = btScalar(1.) / + (computeAngularImpulseDenominator(m_twistAxis,invInertiaWorldA) + + computeAngularImpulseDenominator(m_twistAxis,invInertiaWorldB)); + } + + if (m_solveSwingLimit) + m_twistAxisA = quatRotate(qA, -twistAxis); + } + else + { + m_twistAngle = btScalar(0.f); + } + } +} + + + +// given a cone rotation in constraint space, (pre: twist must already be removed) +// this method computes its corresponding swing angle and axis. +// more interestingly, it computes the cone/swing limit (angle) for this cone "pose". +void btConeTwistConstraint::computeConeLimitInfo(const btQuaternion& qCone, + btScalar& swingAngle, // out + btVector3& vSwingAxis, // out + btScalar& swingLimit) // out +{ + swingAngle = qCone.getAngle(); + if (swingAngle > SIMD_EPSILON) + { + vSwingAxis = btVector3(qCone.x(), qCone.y(), qCone.z()); + vSwingAxis.normalize(); + if (fabs(vSwingAxis.x()) > SIMD_EPSILON) + { + // non-zero twist?! this should never happen. + int wtf = 0; wtf = wtf; + } + + // Compute limit for given swing. tricky: + // Given a swing axis, we're looking for the intersection with the bounding cone ellipse. + // (Since we're dealing with angles, this ellipse is embedded on the surface of a sphere.) + + // For starters, compute the direction from center to surface of ellipse. + // This is just the perpendicular (ie. rotate 2D vector by PI/2) of the swing axis. + // (vSwingAxis is the cone rotation (in z,y); change vars and rotate to (x,y) coords.) + btScalar xEllipse = vSwingAxis.y(); + btScalar yEllipse = -vSwingAxis.z(); + + // Now, we use the slope of the vector (using x/yEllipse) and find the length + // of the line that intersects the ellipse: + // x^2 y^2 + // --- + --- = 1, where a and b are semi-major axes 2 and 1 respectively (ie. the limits) + // a^2 b^2 + // Do the math and it should be clear. + + swingLimit = m_swingSpan1; // if xEllipse == 0, we have a pure vSwingAxis.z rotation: just use swingspan1 + if (fabs(xEllipse) > SIMD_EPSILON) + { + btScalar surfaceSlope2 = (yEllipse*yEllipse)/(xEllipse*xEllipse); + btScalar norm = 1 / (m_swingSpan2 * m_swingSpan2); + norm += surfaceSlope2 / (m_swingSpan1 * m_swingSpan1); + btScalar swingLimit2 = (1 + surfaceSlope2) / norm; + swingLimit = sqrt(swingLimit2); + } + + // test! + /*swingLimit = m_swingSpan2; + if (fabs(vSwingAxis.z()) > SIMD_EPSILON) + { + btScalar mag_2 = m_swingSpan1*m_swingSpan1 + m_swingSpan2*m_swingSpan2; + btScalar sinphi = m_swingSpan2 / sqrt(mag_2); + btScalar phi = asin(sinphi); + btScalar theta = atan2(fabs(vSwingAxis.y()),fabs(vSwingAxis.z())); + btScalar alpha = 3.14159f - theta - phi; + btScalar sinalpha = sin(alpha); + swingLimit = m_swingSpan1 * sinphi/sinalpha; + }*/ + } + else if (swingAngle < 0) + { + // this should never happen! + int wtf = 0; wtf = wtf; + } +} + +btVector3 btConeTwistConstraint::GetPointForAngle(btScalar fAngleInRadians, btScalar fLength) const +{ + // compute x/y in ellipse using cone angle (0 -> 2*PI along surface of cone) + btScalar xEllipse = btCos(fAngleInRadians); + btScalar yEllipse = btSin(fAngleInRadians); + + // Use the slope of the vector (using x/yEllipse) and find the length + // of the line that intersects the ellipse: + // x^2 y^2 + // --- + --- = 1, where a and b are semi-major axes 2 and 1 respectively (ie. the limits) + // a^2 b^2 + // Do the math and it should be clear. + + float swingLimit = m_swingSpan1; // if xEllipse == 0, just use axis b (1) + if (fabs(xEllipse) > SIMD_EPSILON) + { + btScalar surfaceSlope2 = (yEllipse*yEllipse)/(xEllipse*xEllipse); + btScalar norm = 1 / (m_swingSpan2 * m_swingSpan2); + norm += surfaceSlope2 / (m_swingSpan1 * m_swingSpan1); + btScalar swingLimit2 = (1 + surfaceSlope2) / norm; + swingLimit = sqrt(swingLimit2); + } + + // convert into point in constraint space: + // note: twist is x-axis, swing 1 and 2 are along the z and y axes respectively + btVector3 vSwingAxis(0, xEllipse, -yEllipse); + btQuaternion qSwing(vSwingAxis, swingLimit); + btVector3 vPointInConstraintSpace(fLength,0,0); + return quatRotate(qSwing, vPointInConstraintSpace); +} + +// given a twist rotation in constraint space, (pre: cone must already be removed) +// this method computes its corresponding angle and axis. +void btConeTwistConstraint::computeTwistLimitInfo(const btQuaternion& qTwist, + btScalar& twistAngle, // out + btVector3& vTwistAxis) // out +{ + btQuaternion qMinTwist = qTwist; + twistAngle = qTwist.getAngle(); + + if (twistAngle > SIMD_PI) // long way around. flip quat and recalculate. + { + qMinTwist = operator-(qTwist); + twistAngle = qMinTwist.getAngle(); + } + if (twistAngle < 0) + { + // this should never happen + int wtf = 0; wtf = wtf; + } + + vTwistAxis = btVector3(qMinTwist.x(), qMinTwist.y(), qMinTwist.z()); + if (twistAngle > SIMD_EPSILON) + vTwistAxis.normalize(); +} + + +void btConeTwistConstraint::adjustSwingAxisToUseEllipseNormal(btVector3& vSwingAxis) const +{ + // the swing axis is computed as the "twist-free" cone rotation, + // but the cone limit is not circular, but elliptical (if swingspan1 != swingspan2). + // so, if we're outside the limits, the closest way back inside the cone isn't + // along the vector back to the center. better (and more stable) to use the ellipse normal. + + // convert swing axis to direction from center to surface of ellipse + // (ie. rotate 2D vector by PI/2) + btScalar y = -vSwingAxis.z(); + btScalar z = vSwingAxis.y(); + + // do the math... + if (fabs(z) > SIMD_EPSILON) // avoid division by 0. and we don't need an update if z == 0. + { + // compute gradient/normal of ellipse surface at current "point" + btScalar grad = y/z; + grad *= m_swingSpan2 / m_swingSpan1; + + // adjust y/z to represent normal at point (instead of vector to point) + if (y > 0) + y = fabs(grad * z); + else + y = -fabs(grad * z); + + // convert ellipse direction back to swing axis + vSwingAxis.setZ(-y); + vSwingAxis.setY( z); + vSwingAxis.normalize(); + } +} + + + +void btConeTwistConstraint::setMotorTarget(const btQuaternion &q) +{ + btTransform trACur = m_rbA.getCenterOfMassTransform(); + btTransform trBCur = m_rbB.getCenterOfMassTransform(); + btTransform trABCur = trBCur.inverse() * trACur; + btQuaternion qABCur = trABCur.getRotation(); + btTransform trConstraintCur = (trBCur * m_rbBFrame).inverse() * (trACur * m_rbAFrame); + btQuaternion qConstraintCur = trConstraintCur.getRotation(); + + btQuaternion qConstraint = m_rbBFrame.getRotation().inverse() * q * m_rbAFrame.getRotation(); + setMotorTargetInConstraintSpace(qConstraint); +} + + +void btConeTwistConstraint::setMotorTargetInConstraintSpace(const btQuaternion &q) +{ + m_qTarget = q; + + // clamp motor target to within limits + { + btScalar softness = 1.f;//m_limitSoftness; + + // split into twist and cone + btVector3 vTwisted = quatRotate(m_qTarget, vTwist); + btQuaternion qTargetCone = shortestArcQuat(vTwist, vTwisted); qTargetCone.normalize(); + btQuaternion qTargetTwist = qTargetCone.inverse() * m_qTarget; qTargetTwist.normalize(); + + // clamp cone + if (m_swingSpan1 >= btScalar(0.05f) && m_swingSpan2 >= btScalar(0.05f)) + { + btScalar swingAngle, swingLimit; btVector3 swingAxis; + computeConeLimitInfo(qTargetCone, swingAngle, swingAxis, swingLimit); + + if (fabs(swingAngle) > SIMD_EPSILON) + { + if (swingAngle > swingLimit*softness) + swingAngle = swingLimit*softness; + else if (swingAngle < -swingLimit*softness) + swingAngle = -swingLimit*softness; + qTargetCone = btQuaternion(swingAxis, swingAngle); + } + } + + // clamp twist + if (m_twistSpan >= btScalar(0.05f)) + { + btScalar twistAngle; btVector3 twistAxis; + computeTwistLimitInfo(qTargetTwist, twistAngle, twistAxis); + + if (fabs(twistAngle) > SIMD_EPSILON) + { + // eddy todo: limitSoftness used here??? + if (twistAngle > m_twistSpan*softness) + twistAngle = m_twistSpan*softness; + else if (twistAngle < -m_twistSpan*softness) + twistAngle = -m_twistSpan*softness; + qTargetTwist = btQuaternion(twistAxis, twistAngle); + } + } + + m_qTarget = qTargetCone * qTargetTwist; + } +} + +///override the default global value of a parameter (such as ERP or CFM), optionally provide the axis (0..5). +///If no axis is provided, it uses the default axis for this constraint. +void btConeTwistConstraint::setParam(int num, btScalar value, int axis) +{ + switch(num) + { + case BT_CONSTRAINT_ERP : + case BT_CONSTRAINT_STOP_ERP : + if((axis >= 0) && (axis < 3)) + { + m_linERP = value; + m_flags |= BT_CONETWIST_FLAGS_LIN_ERP; + } + else + { + m_biasFactor = value; + } + break; + case BT_CONSTRAINT_CFM : + case BT_CONSTRAINT_STOP_CFM : + if((axis >= 0) && (axis < 3)) + { + m_linCFM = value; + m_flags |= BT_CONETWIST_FLAGS_LIN_CFM; + } + else + { + m_angCFM = value; + m_flags |= BT_CONETWIST_FLAGS_ANG_CFM; + } + break; + default: + btAssertConstrParams(0); + break; + } +} + +///return the local value of parameter +btScalar btConeTwistConstraint::getParam(int num, int axis) const +{ + btScalar retVal = 0; + switch(num) + { + case BT_CONSTRAINT_ERP : + case BT_CONSTRAINT_STOP_ERP : + if((axis >= 0) && (axis < 3)) + { + btAssertConstrParams(m_flags & BT_CONETWIST_FLAGS_LIN_ERP); + retVal = m_linERP; + } + else if((axis >= 3) && (axis < 6)) + { + retVal = m_biasFactor; + } + else + { + btAssertConstrParams(0); + } + break; + case BT_CONSTRAINT_CFM : + case BT_CONSTRAINT_STOP_CFM : + if((axis >= 0) && (axis < 3)) + { + btAssertConstrParams(m_flags & BT_CONETWIST_FLAGS_LIN_CFM); + retVal = m_linCFM; + } + else if((axis >= 3) && (axis < 6)) + { + btAssertConstrParams(m_flags & BT_CONETWIST_FLAGS_ANG_CFM); + retVal = m_angCFM; + } + else + { + btAssertConstrParams(0); + } + break; + default : + btAssertConstrParams(0); + } + return retVal; +} + + + |