/*! Get the position of the body in the universal coordinate system.
* This method uses high-precision coordinates and is thus
* slower relative to getAstrocentricPosition(), which works strictly
* with standard double precision. For most purposes,
* getAstrocentricPosition() should be used instead of the more
* general getPosition().
*/
UniversalCoord Body::getPosition(double tdb) const
{
Vector3d position = Vector3d::Zero();
const TimelinePhase* phase = timeline->findPhase(tdb);
Vector3d p = phase->orbit()->positionAtTime(tdb);
ReferenceFrame* frame = phase->orbitFrame();
while (frame->getCenter().getType() == Selection::Type_Body)
{
phase = frame->getCenter().body()->timeline->findPhase(tdb);
position += frame->getOrientation(tdb).conjugate() * p;
p = phase->orbit()->positionAtTime(tdb);
frame = phase->orbitFrame();
}
position += frame->getOrientation(tdb).conjugate() * p;
if (frame->getCenter().star())
return frame->getCenter().star()->getPosition(tdb).offsetKm(position);
else
return frame->getCenter().getPosition(tdb).offsetKm(position);
}
/*! Get the angular velocity of the body in the universal frame.
*/
Vector3d Body::getAngularVelocity(double tdb) const
{
const TimelinePhase* phase = timeline->findPhase(tdb);
Vector3d v = phase->rotationModel()->angularVelocityAtTime(tdb);
ReferenceFrame* bodyFrame = phase->bodyFrame();
v = bodyFrame->getOrientation(tdb).conjugate() * v;
if (!bodyFrame->isInertial())
{
v += bodyFrame->getAngularVelocity(tdb);
}
return v;
}
/*! Get the velocity of the body in the universal frame.
*/
Vector3d Body::getVelocity(double tdb) const
{
const TimelinePhase* phase = timeline->findPhase(tdb);
ReferenceFrame* orbitFrame = phase->orbitFrame();
Vector3d v = phase->orbit()->velocityAtTime(tdb);
v = orbitFrame->getOrientation(tdb).conjugate() * v + orbitFrame->getCenter().getVelocity(tdb);
if (!orbitFrame->isInertial())
{
Vector3d r = Selection(const_cast<Body*>(this)).getPosition(tdb).offsetFromKm(orbitFrame->getCenter().getPosition(tdb));
v += orbitFrame->getAngularVelocity(tdb).cross(r);
}
return v;
}