void dxStepBody (dxBody *b, dReal h)
{
int j;
#ifdef DEBUG_VALID
dIASSERT(dValid(b->avel[0])&&dValid(b->avel[1])&&dValid(b->avel[2]));
#endif
// handle linear velocity
for (j=0; j<3; j++) b->pos[j] += h * b->lvel[j];
if (b->flags & dxBodyFlagFiniteRotation) {
dVector3 irv; // infitesimal rotation vector
dQuaternion q; // quaternion for finite rotation
if (b->flags & dxBodyFlagFiniteRotationAxis) {
// split the angular velocity vector into a component along the finite
// rotation axis, and a component orthogonal to it.
dVector3 frv; // finite rotation vector
dReal k = dDOT (b->finite_rot_axis,b->avel);
frv[0] = b->finite_rot_axis[0] * k;
frv[1] = b->finite_rot_axis[1] * k;
frv[2] = b->finite_rot_axis[2] * k;
irv[0] = b->avel[0] - frv[0];
irv[1] = b->avel[1] - frv[1];
irv[2] = b->avel[2] - frv[2];
// make a rotation quaternion q that corresponds to frv * h.
// compare this with the full-finite-rotation case below.
h *= REAL(0.5);
dReal theta = k * h;
q[0] = dCos(theta);
dReal s = sinc(theta) * h;
q[1] = frv[0] * s;
q[2] = frv[1] * s;
q[3] = frv[2] * s;
}
else {
// make a rotation quaternion q that corresponds to w * h
dReal wlen = dSqrt (b->avel[0]*b->avel[0] + b->avel[1]*b->avel[1] +
b->avel[2]*b->avel[2]);
h *= REAL(0.5);
dReal theta = wlen * h;
q[0] = dCos(theta);
dReal s = sinc(theta) * h;
q[1] = b->avel[0] * s;
q[2] = b->avel[1] * s;
q[3] = b->avel[2] * s;
}
// do the finite rotation
dQuaternion q2;
dQMultiply0 (q2,q,b->q);
for (j=0; j<4; j++) b->q[j] = q2[j];
// do the infitesimal rotation if required
if (b->flags & dxBodyFlagFiniteRotationAxis) {
dReal dq[4];
dWtoDQ (irv,b->q,dq);
for (j=0; j<4; j++) b->q[j] += h * dq[j];
}
}
else {
// the normal way - do an infitesimal rotation
dReal dq[4];
dWtoDQ (b->avel,b->q,dq);
for (j=0; j<4; j++) b->q[j] += h * dq[j];
}
// normalize the quaternion and convert it to a rotation matrix
dNormalize4 (b->q);
dQtoR (b->q,b->R);
// notify all attached geoms that this body has moved
for (dxGeom *geom = b->geom; geom; geom = dGeomGetBodyNext (geom))
dGeomMoved (geom);
#ifdef DEBUG_VALID
dIASSERT(dValid(b->avel[0])&&dValid(b->avel[1])&&dValid(b->avel[2]));
#endif
}
void dxStepBody (dxBody *b, dReal h)
{
// cap the angular velocity
if (b->flags & dxBodyMaxAngularSpeed) {
const dReal max_ang_speed = b->max_angular_speed;
const dReal aspeed = dCalcVectorDot3( b->avel, b->avel );
if (aspeed > max_ang_speed*max_ang_speed) {
const dReal coef = max_ang_speed/dSqrt(aspeed);
dScaleVector3(b->avel, coef);
}
}
// end of angular velocity cap
// handle linear velocity
for (unsigned int j=0; j<3; j++) b->posr.pos[j] += h * b->lvel[j];
if (b->flags & dxBodyFlagFiniteRotation) {
dVector3 irv; // infitesimal rotation vector
dQuaternion q; // quaternion for finite rotation
if (b->flags & dxBodyFlagFiniteRotationAxis) {
// split the angular velocity vector into a component along the finite
// rotation axis, and a component orthogonal to it.
dVector3 frv; // finite rotation vector
dReal k = dCalcVectorDot3 (b->finite_rot_axis,b->avel);
frv[0] = b->finite_rot_axis[0] * k;
frv[1] = b->finite_rot_axis[1] * k;
frv[2] = b->finite_rot_axis[2] * k;
irv[0] = b->avel[0] - frv[0];
irv[1] = b->avel[1] - frv[1];
irv[2] = b->avel[2] - frv[2];
// make a rotation quaternion q that corresponds to frv * h.
// compare this with the full-finite-rotation case below.
h *= REAL(0.5);
dReal theta = k * h;
q[0] = dCos(theta);
dReal s = sinc(theta) * h;
q[1] = frv[0] * s;
q[2] = frv[1] * s;
q[3] = frv[2] * s;
}
else {
// make a rotation quaternion q that corresponds to w * h
dReal wlen = dSqrt (b->avel[0]*b->avel[0] + b->avel[1]*b->avel[1] +
b->avel[2]*b->avel[2]);
h *= REAL(0.5);
dReal theta = wlen * h;
q[0] = dCos(theta);
dReal s = sinc(theta) * h;
q[1] = b->avel[0] * s;
q[2] = b->avel[1] * s;
q[3] = b->avel[2] * s;
}
// do the finite rotation
dQuaternion q2;
dQMultiply0 (q2,q,b->q);
for (unsigned int j=0; j<4; j++) b->q[j] = q2[j];
// do the infitesimal rotation if required
if (b->flags & dxBodyFlagFiniteRotationAxis) {
dReal dq[4];
dWtoDQ (irv,b->q,dq);
for (unsigned int j=0; j<4; j++) b->q[j] += h * dq[j];
}
}
else {
// the normal way - do an infitesimal rotation
dReal dq[4];
dWtoDQ (b->avel,b->q,dq);
for (unsigned int j=0; j<4; j++) b->q[j] += h * dq[j];
}
// normalize the quaternion and convert it to a rotation matrix
dNormalize4 (b->q);
dQtoR (b->q,b->posr.R);
// notify all attached geoms that this body has moved
dxWorldProcessContext *world_process_context = b->world->UnsafeGetWorldProcessingContext();
for (dxGeom *geom = b->geom; geom; geom = dGeomGetBodyNext (geom)) {
world_process_context->LockForStepbodySerialization();
dGeomMoved (geom);
world_process_context->UnlockForStepbodySerialization();
}
// notify the user
if (b->moved_callback != NULL) {
b->moved_callback(b);
}
// damping
if (b->flags & dxBodyLinearDamping) {
const dReal lin_threshold = b->dampingp.linear_threshold;
const dReal lin_speed = dCalcVectorDot3( b->lvel, b->lvel );
if ( lin_speed > lin_threshold) {
const dReal k = 1 - b->dampingp.linear_scale;
dScaleVector3(b->lvel, k);
}
}
if (b->flags & dxBodyAngularDamping) {
const dReal ang_threshold = b->dampingp.angular_threshold;
const dReal ang_speed = dCalcVectorDot3( b->avel, b->avel );
if ( ang_speed > ang_threshold) {
const dReal k = 1 - b->dampingp.angular_scale;
dScaleVector3(b->avel, k);
}
}
}
static inline void
moveAndRotateBody (dxBody * b, dReal h)
{
int j;
// handle linear velocity
for (j = 0; j < 3; j++)
b->posr.pos[j] += dMUL(h,b->lvel[j]);
if (b->flags & dxBodyFlagFiniteRotation)
{
dVector3 irv; // infitesimal rotation vector
dQuaternion q; // quaternion for finite rotation
if (b->flags & dxBodyFlagFiniteRotationAxis)
{
// split the angular velocity vector into a component along the finite
// rotation axis, and a component orthogonal to it.
dVector3 frv; // finite rotation vector
dReal k = dDOT (b->finite_rot_axis, b->avel);
frv[0] = dMUL(b->finite_rot_axis[0],k);
frv[1] = dMUL(b->finite_rot_axis[1],k);
frv[2] = dMUL(b->finite_rot_axis[2],k);
irv[0] = b->avel[0] - frv[0];
irv[1] = b->avel[1] - frv[1];
irv[2] = b->avel[2] - frv[2];
// make a rotation quaternion q that corresponds to frv * h.
// compare this with the full-finite-rotation case below.
h = dMUL(h,REAL (0.5));
dReal theta = dMUL(k,h);
q[0] = dCos (theta);
dReal s = dMUL(sinc (theta),h);
q[1] = dMUL(frv[0],s);
q[2] = dMUL(frv[1],s);
q[3] = dMUL(frv[2],s);
}
else
{
// make a rotation quaternion q that corresponds to w * h
dReal wlen = dSqrt (dMUL(b->avel[0],b->avel[0]) + dMUL(b->avel[1],b->avel[1]) + dMUL(b->avel[2],b->avel[2]));
h = dMUL(h,REAL (0.5));
dReal theta = dMUL(wlen,h);
q[0] = dCos (theta);
dReal s = dMUL(sinc (theta),h);
q[1] = dMUL(b->avel[0],s);
q[2] = dMUL(b->avel[1],s);
q[3] = dMUL(b->avel[2],s);
}
// do the finite rotation
dQuaternion q2;
dQMultiply0 (q2, q, b->q);
for (j = 0; j < 4; j++)
b->q[j] = q2[j];
// do the infitesimal rotation if required
if (b->flags & dxBodyFlagFiniteRotationAxis)
{
dReal dq[4];
dWtoDQ (irv, b->q, dq);
for (j = 0; j < 4; j++)
b->q[j] += dMUL(h,dq[j]);
}
}
else
{
// the normal way - do an infitesimal rotation
dReal dq[4];
dWtoDQ (b->avel, b->q, dq);
for (j = 0; j < 4; j++)
b->q[j] += dMUL(h,dq[j]);
}
// normalize the quaternion and convert it to a rotation matrix
dNormalize4 (b->q);
dQtoR (b->q, b->posr.R);
// notify all attached geoms that this body has moved
for (dxGeom * geom = b->geom; geom; geom = dGeomGetBodyNext (geom))
dGeomMoved (geom);
}
