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#include <cmath> |
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#include "Mat3x3d.hpp" |
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#include "Roll.hpp" |
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#include "SimInfo.hpp" |
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|
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|
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//////////////////////////////////////////////////////////////////////////////// |
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//Implementation of DCRollAFunctor |
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//////////////////////////////////////////////////////////////////////////////// |
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int DCRollAFunctor::operator()(ConstraintRigidBody* consRB1, ConstraintRigidBody* consRB2){ |
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Vector3d posA; |
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Vector3d posB; |
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Vector3d oldPosA; |
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Vector3d oldPosB; |
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Vector3d velA; |
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Vector3d velB; |
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Vector3d pab; |
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Vector3d tempPab; |
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Vector3d rab; |
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Vector3d rma; |
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Vector3d rmb; |
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Vector3d consForce; |
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Vector3d bondDirUnitVec; |
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double dx, dy, dz; |
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double rpab; |
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double rabsq, pabsq, rpabsq; |
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double diffsq; |
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double gab; |
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double dt; |
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double dt2; |
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double rijcDotInvMassVec; |
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|
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|
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const int conRBMaxIter = 10; |
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|
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dt = info->dt; |
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dt2 = dt * dt; |
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|
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consRB1->getOldAtomPos(oldPosA.vec); |
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consRB2->getOldAtomPos(oldPosB.vec); |
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|
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|
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for(int i=0 ; i < conRBMaxIter; i++){ |
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consRB1->getCurAtomPos(posA.vec); |
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consRB2->getCurAtomPos(posB.vec); |
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|
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pab = posA - posB; |
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|
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//periodic boundary condition |
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|
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info->wrapVector(pab.vec); |
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pabsq = dotProduct(pab, pab); |
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|
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rabsq = curPair->getBondLength2(); |
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diffsq = rabsq - pabsq; |
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|
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if (fabs(diffsq) > (consTolerance * rabsq * 2)){ |
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rab = oldPosA - oldPosB; |
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info->wrapVector(rab.vec); |
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|
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rpab = dotProduct(rab, pab); |
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rpabsq = rpab * rpab; |
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|
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//if (rpabsq < (rabsq * -diffsq)){ |
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// return consFail; |
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//} |
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|
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bondDirUnitVec = pab; |
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bondDirUnitVec.normalize(); |
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|
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getEffInvMassVec(consRB1, bondDirUnitVec, rma); |
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|
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getEffInvMassVec(consRB2, -bondDirUnitVec, rmb); |
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rijcDotInvMassVec = dotProduct(pab, rma + rmb); |
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|
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consForce = diffsq /(2 * dt * dt * rijcDotInvMassVec) * bondDirUnitVec; |
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//integrate consRB1 using constraint force; |
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integrate(consRB1,consForce); |
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|
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//integrate consRB2 using constraint force; |
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integrate(consRB2, -consForce); |
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|
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} |
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else{ |
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if (i ==0) |
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return consAlready; |
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else |
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return consSuccess; |
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} |
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} |
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|
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return consExceedMaxIter; |
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|
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} |
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|
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void DCRollAFunctor::getEffInvMassVec(ConstraintRigidBody* consRB, const Vector3d& bondDir, Vector3d& invMassVec){ |
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double invMass; |
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Vector3d tempVec1; |
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Vector3d tempVec2; |
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Vector3d refCoor; |
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Vector3d refCrossBond; |
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Mat3x3d IBody; |
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Mat3x3d IFrame; |
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Mat3x3d invIBody; |
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Mat3x3d invIFrame; |
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Mat3x3d a; |
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Mat3x3d aTrans; |
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invMass = 1.0 / consRB ->getMass(); |
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invMassVec = invMass * bondDir; |
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consRB->getRefCoor(refCoor.vec); |
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consRB->getA(a.element); |
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consRB->getI(IBody.element); |
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aTrans = a.transpose(); |
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invIBody = IBody.inverse(); |
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IFrame = aTrans * invIBody * a; |
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refCrossBond = crossProduct(refCoor, bondDir); |
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tempVec1 = invIFrame * refCrossBond; |
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tempVec2 = crossProduct(tempVec1, refCoor); |
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invMassVec += tempVec2; |
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} |
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|
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void DCRollAFunctor::integrate(ConstraintRigidBody* consRB, const Vector3d& force){ |
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StuntDouble* sd; |
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Vector3d vel; |
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Vector3d pos; |
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Vector3d Tb; |
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Vector3d ji; |
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double mass; |
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double dtOver2; |
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double dt; |
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const double eConvert = 4.184e-4; |
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|
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dt = info->dt; |
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dtOver2 = dt /2; |
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sd = consRB->getStuntDouble(); |
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sd->getVel(vel.vec); |
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sd->getPos(pos.vec); |
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mass = sd->getMass(); |
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vel += eConvert * dtOver2/mass * force; |
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pos += dt * vel; |
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sd->setVel(vel.vec); |
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sd->setPos(pos.vec); |
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|
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if (sd->isDirectional()){ |
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// get and convert the torque to body frame |
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sd->getTrq(Tb.vec); |
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sd->lab2Body(Tb.vec); |
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// get the angular momentum, and propagate a half step |
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sd->getJ(ji.vec); |
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ji += eConvert * dtOver2 * Tb; |
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rotationPropagation( sd, ji.vec); |
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sd->setJ(ji.vec); |
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} |
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|
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} |
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|
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void DCRollAFunctor::rotationPropagation(StuntDouble* sd, double ji[3]){ |
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double angle; |
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double A[3][3], I[3][3]; |
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int i, j, k; |
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double dtOver2; |
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|
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dtOver2 = info->dt /2; |
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// use the angular velocities to propagate the rotation matrix a |
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// full time step |
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|
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sd->getA(A); |
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sd->getI(I); |
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|
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if (sd->isLinear()) { |
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i = sd->linearAxis(); |
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j = (i+1)%3; |
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k = (i+2)%3; |
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angle = dtOver2 * ji[j] / I[j][j]; |
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this->rotate( k, i, angle, ji, A ); |
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angle = dtOver2 * ji[k] / I[k][k]; |
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this->rotate( i, j, angle, ji, A); |
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angle = dtOver2 * ji[j] / I[j][j]; |
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this->rotate( k, i, angle, ji, A ); |
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|
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} else { |
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// rotate about the x-axis |
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angle = dtOver2 * ji[0] / I[0][0]; |
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this->rotate( 1, 2, angle, ji, A ); |
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// rotate about the y-axis |
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angle = dtOver2 * ji[1] / I[1][1]; |
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this->rotate( 2, 0, angle, ji, A ); |
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// rotate about the z-axis |
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angle = dtOver2 * ji[2] / I[2][2]; |
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sd->addZangle(angle); |
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this->rotate( 0, 1, angle, ji, A); |
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// rotate about the y-axis |
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angle = dtOver2 * ji[1] / I[1][1]; |
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this->rotate( 2, 0, angle, ji, A ); |
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// rotate about the x-axis |
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angle = dtOver2 * ji[0] / I[0][0]; |
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this->rotate( 1, 2, angle, ji, A ); |
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|
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} |
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sd->setA( A ); |
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} |
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|
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void DCRollAFunctor::rotate(int axes1, int axes2, double angle, double ji[3], double A[3][3]){ |
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int i, j, k; |
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double sinAngle; |
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double cosAngle; |
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double angleSqr; |
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double angleSqrOver4; |
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double top, bottom; |
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double rot[3][3]; |
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double tempA[3][3]; |
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double tempJ[3]; |
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|
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// initialize the tempA |
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for (i = 0; i < 3; i++){ |
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for (j = 0; j < 3; j++){ |
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tempA[j][i] = A[i][j]; |
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} |
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} |
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// initialize the tempJ |
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for (i = 0; i < 3; i++) |
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tempJ[i] = ji[i]; |
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// initalize rot as a unit matrix |
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rot[0][0] = 1.0; |
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rot[0][1] = 0.0; |
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rot[0][2] = 0.0; |
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|
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rot[1][0] = 0.0; |
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rot[1][1] = 1.0; |
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rot[1][2] = 0.0; |
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|
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rot[2][0] = 0.0; |
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rot[2][1] = 0.0; |
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rot[2][2] = 1.0; |
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// use a small angle aproximation for sin and cosine |
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angleSqr = angle * angle; |
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angleSqrOver4 = angleSqr / 4.0; |
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top = 1.0 - angleSqrOver4; |
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bottom = 1.0 + angleSqrOver4; |
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cosAngle = top / bottom; |
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sinAngle = angle / bottom; |
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rot[axes1][axes1] = cosAngle; |
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rot[axes2][axes2] = cosAngle; |
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|
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rot[axes1][axes2] = sinAngle; |
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rot[axes2][axes1] = -sinAngle; |
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// rotate the momentum acoording to: ji[] = rot[][] * ji[] |
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for (i = 0; i < 3; i++){ |
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ji[i] = 0.0; |
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for (k = 0; k < 3; k++){ |
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ji[i] += rot[i][k] * tempJ[k]; |
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} |
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} |
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|
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// rotate the Rotation matrix acording to: |
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// A[][] = A[][] * transpose(rot[][]) |
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|
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|
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// NOte for as yet unknown reason, we are performing the |
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// calculation as: |
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// transpose(A[][]) = transpose(A[][]) * transpose(rot[][]) |
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|
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for (i = 0; i < 3; i++){ |
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for (j = 0; j < 3; j++){ |
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A[j][i] = 0.0; |
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for (k = 0; k < 3; k++){ |
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A[j][i] += tempA[i][k] * rot[j][k]; |
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} |
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} |
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} |
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} |
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//////////////////////////////////////////////////////////////////////////////// |
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//Implementation of DCRollBFunctor |
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//////////////////////////////////////////////////////////////////////////////// |
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int DCRollBFunctor::operator()(ConstraintRigidBody* consRB1, ConstraintRigidBody* consRB2){ |
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return consElemHandlerFail; |
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} |
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|
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void DCRollBFunctor::getEffInvMassVec(ConstraintRigidBody* consRB, const Vector3d& bondDir, Vector3d& invMassVec){ |
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|
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} |
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|
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void DCRollBFunctor::integrate(ConstraintRigidBody* consRB, const Vector3d& force){ |
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|
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} |
