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Improved Slider, Hinge and Generic6DOF constraint setup.

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Turned on by default, use m_useOffsetForConstraintFrame = false to use old setup
Use "O" (capital 'o') button to toggle it in SliderConstraintDemo and ConstraintDemo

Total applied impulse copied back from btSolverConstraint to btTypedConstraint
This commit is contained in:
rponom
2009-11-25 23:52:12 +00:00
parent eea73bc76a
commit f919baf03d
15 changed files with 1082 additions and 114 deletions
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382
src/BulletDynamics/ConstraintSolver/btSliderConstraint.cpp
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@@ -25,7 +25,7 @@ April 04, 2008
#include "LinearMath/btTransformUtil.h"
#include <new>
#define USE_OFFSET_FOR_CONSTANT_FRAME true
void btSliderConstraint::initParams()
{
@@ -62,6 +62,9 @@ void btSliderConstraint::initParams()
m_maxAngMotorForce = btScalar(0.);
m_accumulatedAngMotorImpulse = btScalar(0.0);
m_useLinearReferenceFrameA = USE_OFFSET_FOR_CONSTANT_FRAME;
}
@@ -80,8 +83,7 @@ btSliderConstraint::btSliderConstraint(btRigidBody& rbA, btRigidBody& rbB, const
: btTypedConstraint(SLIDER_CONSTRAINT_TYPE, rbA, rbB),
m_useSolveConstraintObsolete(false),
m_frameInA(frameInA),
m_frameInB(frameInB),
m_useLinearReferenceFrameA(useLinearReferenceFrameA)
m_frameInB(frameInB)
{
initParams();
}
@@ -175,7 +177,6 @@ void btSliderConstraint::buildJacobianInt(btRigidBody& rbA, btRigidBody& rbB, co
#endif //__SPU__
}
void btSliderConstraint::getInfo1(btConstraintInfo1* info)
{
if (m_useSolveConstraintObsolete)
@@ -189,13 +190,13 @@ void btSliderConstraint::getInfo1(btConstraintInfo1* info)
info->nub = 2;
//prepare constraint
calculateTransforms(m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform());
testAngLimits();
testLinLimits();
if(getSolveLinLimit() || getPoweredLinMotor())
{
info->m_numConstraintRows++; // limit 3rd linear as well
info->nub--;
}
testAngLimits();
if(getSolveAngLimit() || getPoweredAngMotor())
{
info->m_numConstraintRows++; // limit 3rd angular as well
@@ -213,7 +214,14 @@ void btSliderConstraint::getInfo1NonVirtual(btConstraintInfo1* info)
void btSliderConstraint::getInfo2(btConstraintInfo2* info)
{
getInfo2NonVirtual(info,m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform(), m_rbA.getLinearVelocity(),m_rbB.getLinearVelocity(), m_rbA.getInvMass(),m_rbB.getInvMass());
if(m_useOffsetForConstraintFrame)
{
getInfo2NonVirtualUsingFrameOffset(info,m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform(), m_rbA.getLinearVelocity(),m_rbB.getLinearVelocity(), m_rbA.getInvMass(),m_rbB.getInvMass());
}
else
{
getInfo2NonVirtual(info,m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform(), m_rbA.getLinearVelocity(),m_rbB.getLinearVelocity(), m_rbA.getInvMass(),m_rbB.getInvMass());
}
}
void btSliderConstraint::getInfo2NonVirtual(btConstraintInfo2* info, const btTransform& transA,const btTransform& transB, const btVector3& linVelA,const btVector3& linVelB, btScalar rbAinvMass,btScalar rbBinvMass )
@@ -532,7 +540,6 @@ void btSliderConstraint::getInfo2NonVirtual(btConstraintInfo2* info, const btTra
}
void btSliderConstraint::solveConstraintObsolete(btSolverBody& bodyA,btSolverBody& bodyB,btScalar timeStep)
{
if (m_useSolveConstraintObsolete)
@@ -830,8 +837,6 @@ void btSliderConstraint::testAngLimits(void)
}
}
}
btVector3 btSliderConstraint::getAncorInA(void)
{
@@ -849,3 +854,362 @@ btVector3 btSliderConstraint::getAncorInB(void)
ancorInB = m_frameInB.getOrigin();
return ancorInB;
}
void btSliderConstraint::getInfo2NonVirtualUsingFrameOffset(btConstraintInfo2* info, const btTransform& transA,const btTransform& transB, const btVector3& linVelA,const btVector3& linVelB, btScalar rbAinvMass,btScalar rbBinvMass )
{
const btTransform& trA = getCalculatedTransformA();
const btTransform& trB = getCalculatedTransformB();
btAssert(!m_useSolveConstraintObsolete);
int i, s = info->rowskip;
btScalar signFact = m_useLinearReferenceFrameA ? btScalar(1.0f) : btScalar(-1.0f);
// difference between frames in WCS
btVector3 ofs = trB.getOrigin() - trA.getOrigin();
// now get weight factors depending on masses
btScalar miA = rbAinvMass;
btScalar miB = rbBinvMass;
bool hasStaticBody = (miA < SIMD_EPSILON) || (miB < SIMD_EPSILON);
btScalar miS = miA + miB;
btScalar factA, factB;
if(miS > btScalar(0.f))
{
factA = miB / miS;
}
else
{
factA = btScalar(0.5f);
}
factB = btScalar(1.0f) - factA;
// get the desired direction of slider axis
// as weighted sum of X-orthos of frameA and frameB in WCS
btVector3 ax1A = trA.getBasis().getColumn(0);
btVector3 ax1B = trB.getBasis().getColumn(0);
btVector3 ax1 = ax1A * factA + ax1B * factB;
ax1.normalize();
// construct two orthos to slider axis
btVector3 p, q;
btPlaneSpace1 (ax1, p, q);
// make rotations around these orthos equal
// the slider axis should be the only unconstrained
// rotational axis, the angular velocity of the two bodies perpendicular to
// the slider axis should be equal. thus the constraint equations are
// p*w1 - p*w2 = 0
// q*w1 - q*w2 = 0
// where p and q are unit vectors normal to the slider axis, and w1 and w2
// are the angular velocity vectors of the two bodies.
info->m_J1angularAxis[0] = p[0];
info->m_J1angularAxis[1] = p[1];
info->m_J1angularAxis[2] = p[2];
info->m_J1angularAxis[s+0] = q[0];
info->m_J1angularAxis[s+1] = q[1];
info->m_J1angularAxis[s+2] = q[2];
info->m_J2angularAxis[0] = -p[0];
info->m_J2angularAxis[1] = -p[1];
info->m_J2angularAxis[2] = -p[2];
info->m_J2angularAxis[s+0] = -q[0];
info->m_J2angularAxis[s+1] = -q[1];
info->m_J2angularAxis[s+2] = -q[2];
// compute the right hand side of the constraint equation. set relative
// body velocities along p and q to bring the slider back into alignment.
// if ax1A,ax1B are the unit length slider axes as computed from bodyA and
// bodyB, we need to rotate both bodies along the axis u = (ax1 x ax2).
// if "theta" is the angle between ax1 and ax2, we need an angular velocity
// along u to cover angle erp*theta in one step :
// |angular_velocity| = angle/time = erp*theta / stepsize
// = (erp*fps) * theta
// angular_velocity = |angular_velocity| * (ax1 x ax2) / |ax1 x ax2|
// = (erp*fps) * theta * (ax1 x ax2) / sin(theta)
// ...as ax1 and ax2 are unit length. if theta is smallish,
// theta ~= sin(theta), so
// angular_velocity = (erp*fps) * (ax1 x ax2)
// ax1 x ax2 is in the plane space of ax1, so we project the angular
// velocity to p and q to find the right hand side.
btScalar k = info->fps * info->erp * getSoftnessOrthoAng();
btVector3 u = ax1A.cross(ax1B);
info->m_constraintError[0] = k * u.dot(p);
info->m_constraintError[s] = k * u.dot(q);
int nrow = 1; // last filled row
int srow;
btScalar limit_err;
int limit;
int powered;
// next two rows.
// we want: velA + wA x relA == velB + wB x relB ... but this would
// result in three equations, so we project along two orthos to the slider axis
btTransform bodyA_trans = transA;
btTransform bodyB_trans = transB;
nrow++;
int s2 = nrow * s;
nrow++;
int s3 = nrow * s;
btVector3 tmpA, tmpB, relA, relB;
// get vector from bodyB to frameB in WCS
relB = trB.getOrigin() - bodyB_trans.getOrigin();
// get its projection to slider axis
btVector3 projB = ax1 * relB.dot(ax1);
// get vector directed from bodyB to slider axis (and orthogonal to it)
btVector3 orthoB = relB - projB;
// same for bodyA
relA = trA.getOrigin() - bodyA_trans.getOrigin();
btVector3 projA = ax1 * relA.dot(ax1);
btVector3 orthoA = relA - projA;
// get desired offset between frames A and B along slider axis
btScalar sliderOffs = m_linPos - m_depth[0];
// desired vector from projection of center of bodyA to projection of center of bodyB to slider axis
btVector3 totalDist = projA + ax1 * sliderOffs - projB;
// get offset vectors relA and relB
relA = orthoA + totalDist * factA;
relB = orthoB - totalDist * factB;
// now choose average ortho to slider axis
p = orthoB * factA + orthoA * factB;
btScalar len2 = p.length2();
if(len2 > SIMD_EPSILON)
{
p /= btSqrt(len2);
}
else
{
p = trA.getBasis().getColumn(1);
}
// make one more ortho
q = ax1.cross(p);
// fill two rows
tmpA = relA.cross(p);
tmpB = relB.cross(p);
for (i=0; i<3; i++) info->m_J1angularAxis[s2+i] = tmpA[i];
for (i=0; i<3; i++) info->m_J2angularAxis[s2+i] = -tmpB[i];
tmpA = relA.cross(q);
tmpB = relB.cross(q);
if(hasStaticBody && getSolveAngLimit())
{ // to make constraint between static and dynamic objects more rigid
// remove wA (or wB) from equation if angular limit is hit
tmpB *= factB;
tmpA *= factA;
}
for (i=0; i<3; i++) info->m_J1angularAxis[s3+i] = tmpA[i];
for (i=0; i<3; i++) info->m_J2angularAxis[s3+i] = -tmpB[i];
for (i=0; i<3; i++) info->m_J1linearAxis[s2+i] = p[i];
for (i=0; i<3; i++) info->m_J1linearAxis[s3+i] = q[i];
// compute two elements of right hand side
k = info->fps * info->erp * getSoftnessOrthoLin();
btScalar rhs = k * p.dot(ofs);
info->m_constraintError[s2] = rhs;
rhs = k * q.dot(ofs);
info->m_constraintError[s3] = rhs;
// check linear limits
limit_err = btScalar(0.0);
limit = 0;
if(getSolveLinLimit())
{
limit_err = getLinDepth() * signFact;
limit = (limit_err > btScalar(0.0)) ? 2 : 1;
}
powered = 0;
if(getPoweredLinMotor())
{
powered = 1;
}
// if the slider has joint limits or motor, add in the extra row
if (limit || powered)
{
nrow++;
srow = nrow * info->rowskip;
info->m_J1linearAxis[srow+0] = ax1[0];
info->m_J1linearAxis[srow+1] = ax1[1];
info->m_J1linearAxis[srow+2] = ax1[2];
// linear torque decoupling step:
//
// we have to be careful that the linear constraint forces (+/- ax1) applied to the two bodies
// do not create a torque couple. in other words, the points that the
// constraint force is applied at must lie along the same ax1 axis.
// a torque couple will result in limited slider-jointed free
// bodies from gaining angular momentum.
// this is needed only when bodyA and bodyB are both dynamic.
if(!hasStaticBody)
{
tmpA = relA.cross(ax1);
tmpB = relB.cross(ax1);
info->m_J1angularAxis[srow+0] = tmpA[0];
info->m_J1angularAxis[srow+1] = tmpA[1];
info->m_J1angularAxis[srow+2] = tmpA[2];
info->m_J2angularAxis[srow+0] = -tmpB[0];
info->m_J2angularAxis[srow+1] = -tmpB[1];
info->m_J2angularAxis[srow+2] = -tmpB[2];
}
// right-hand part
btScalar lostop = getLowerLinLimit();
btScalar histop = getUpperLinLimit();
if(limit && (lostop == histop))
{ // the joint motor is ineffective
powered = 0;
}
info->m_constraintError[srow] = 0.;
info->m_lowerLimit[srow] = 0.;
info->m_upperLimit[srow] = 0.;
if(powered)
{
info->cfm[nrow] = btScalar(0.0);
btScalar tag_vel = getTargetLinMotorVelocity();
btScalar mot_fact = getMotorFactor(m_linPos, m_lowerLinLimit, m_upperLinLimit, tag_vel, info->fps * info->erp);
info->m_constraintError[srow] -= signFact * mot_fact * getTargetLinMotorVelocity();
info->m_lowerLimit[srow] += -getMaxLinMotorForce() * info->fps;
info->m_upperLimit[srow] += getMaxLinMotorForce() * info->fps;
}
if(limit)
{
k = info->fps * info->erp;
info->m_constraintError[srow] += k * limit_err;
info->cfm[srow] = btScalar(0.0); // stop_cfm;
if(lostop == histop)
{ // limited low and high simultaneously
info->m_lowerLimit[srow] = -SIMD_INFINITY;
info->m_upperLimit[srow] = SIMD_INFINITY;
}
else if(limit == 1)
{ // low limit
info->m_lowerLimit[srow] = -SIMD_INFINITY;
info->m_upperLimit[srow] = 0;
}
else
{ // high limit
info->m_lowerLimit[srow] = 0;
info->m_upperLimit[srow] = SIMD_INFINITY;
}
// bounce (we'll use slider parameter abs(1.0 - m_dampingLimLin) for that)
btScalar bounce = btFabs(btScalar(1.0) - getDampingLimLin());
if(bounce > btScalar(0.0))
{
btScalar vel = linVelA.dot(ax1);
vel -= linVelB.dot(ax1);
vel *= signFact;
// only apply bounce if the velocity is incoming, and if the
// resulting c[] exceeds what we already have.
if(limit == 1)
{ // low limit
if(vel < 0)
{
btScalar newc = -bounce * vel;
if (newc > info->m_constraintError[srow])
{
info->m_constraintError[srow] = newc;
}
}
}
else
{ // high limit - all those computations are reversed
if(vel > 0)
{
btScalar newc = -bounce * vel;
if(newc < info->m_constraintError[srow])
{
info->m_constraintError[srow] = newc;
}
}
}
}
info->m_constraintError[srow] *= getSoftnessLimLin();
} // if(limit)
} // if linear limit
// check angular limits
limit_err = btScalar(0.0);
limit = 0;
if(getSolveAngLimit())
{
limit_err = getAngDepth();
limit = (limit_err > btScalar(0.0)) ? 1 : 2;
}
// if the slider has joint limits, add in the extra row
powered = 0;
if(getPoweredAngMotor())
{
powered = 1;
}
if(limit || powered)
{
nrow++;
srow = nrow * info->rowskip;
info->m_J1angularAxis[srow+0] = ax1[0];
info->m_J1angularAxis[srow+1] = ax1[1];
info->m_J1angularAxis[srow+2] = ax1[2];
info->m_J2angularAxis[srow+0] = -ax1[0];
info->m_J2angularAxis[srow+1] = -ax1[1];
info->m_J2angularAxis[srow+2] = -ax1[2];
btScalar lostop = getLowerAngLimit();
btScalar histop = getUpperAngLimit();
if(limit && (lostop == histop))
{ // the joint motor is ineffective
powered = 0;
}
if(powered)
{
info->cfm[srow] = btScalar(0.0);
btScalar mot_fact = getMotorFactor(m_angPos, m_lowerAngLimit, m_upperAngLimit, getTargetAngMotorVelocity(), info->fps * info->erp);
info->m_constraintError[srow] = mot_fact * getTargetAngMotorVelocity();
info->m_lowerLimit[srow] = -getMaxAngMotorForce() * info->fps;
info->m_upperLimit[srow] = getMaxAngMotorForce() * info->fps;
}
if(limit)
{
k = info->fps * info->erp;
info->m_constraintError[srow] += k * limit_err;
info->cfm[srow] = btScalar(0.0); // stop_cfm;
if(lostop == histop)
{
// limited low and high simultaneously
info->m_lowerLimit[srow] = -SIMD_INFINITY;
info->m_upperLimit[srow] = SIMD_INFINITY;
}
else if(limit == 1)
{ // low limit
info->m_lowerLimit[srow] = 0;
info->m_upperLimit[srow] = SIMD_INFINITY;
}
else
{ // high limit
info->m_lowerLimit[srow] = -SIMD_INFINITY;
info->m_upperLimit[srow] = 0;
}
// bounce (we'll use slider parameter abs(1.0 - m_dampingLimAng) for that)
btScalar bounce = btFabs(btScalar(1.0) - getDampingLimAng());
if(bounce > btScalar(0.0))
{
btScalar vel = m_rbA.getAngularVelocity().dot(ax1);
vel -= m_rbB.getAngularVelocity().dot(ax1);
// only apply bounce if the velocity is incoming, and if the
// resulting c[] exceeds what we already have.
if(limit == 1)
{ // low limit
if(vel < 0)
{
btScalar newc = -bounce * vel;
if(newc > info->m_constraintError[srow])
{
info->m_constraintError[srow] = newc;
}
}
}
else
{ // high limit - all those computations are reversed
if(vel > 0)
{
btScalar newc = -bounce * vel;
if(newc < info->m_constraintError[srow])
{
info->m_constraintError[srow] = newc;
}
}
}
}
info->m_constraintError[srow] *= getSoftnessLimAng();
} // if(limit)
} // if angular limit or powered
}