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flightgear/utils/fgai/AIPhysics.cxx
2012-11-24 10:34:08 +01:00

104 lines
3.9 KiB
C++

// Copyright (C) 2009 - 2012 Mathias Froehlich
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "AIPhysics.hxx"
#include <simgear/math/SGGeometry.hxx>
#include "AIEnvironment.hxx"
namespace fgai {
AIPhysics::AIPhysics(const AIPhysics& physics) :
_location(physics._location),
_linearBodyVelocity(physics._linearBodyVelocity),
_angularBodyVelocity(physics._angularBodyVelocity),
_geodPosition(physics._geodPosition),
_horizontalLocalOrientation(physics._horizontalLocalOrientation)
{
}
AIPhysics::AIPhysics(const SGLocationd& location, const SGVec3d& linearBodyVelocity,
const SGVec3d& angularBodyVelocity) :
_location(location),
_linearBodyVelocity(linearBodyVelocity),
_angularBodyVelocity(angularBodyVelocity)
{
_geodPosition = SGGeod::fromCart(_location.getPosition());
_horizontalLocalOrientation = SGQuatd::fromLonLat(_geodPosition);
}
AIPhysics::~AIPhysics()
{
}
void
AIPhysics::update(AIObject& object, const SGTimeStamp& dt)
{
advanceByBodyVelocity(dt.toSecs(), _linearBodyVelocity, _angularBodyVelocity);
}
void
AIPhysics::advanceByBodyAcceleration(const double& dt,
const SGVec3d& linearAcceleration,
const SGVec3d& angularAcceleration)
{
// The current linear and angular velocity
SGVec3d linearVelocity = getLinearBodyVelocity();
SGVec3d angularVelocity = getAngularBodyVelocity();
// an euler step for the velocities, the positions get upgraded below
linearVelocity += dt*linearAcceleration;
angularVelocity += dt*angularAcceleration;
advanceByBodyVelocity(dt, linearVelocity, angularVelocity);
}
void
AIPhysics::advanceByBodyVelocity(const double& dt,
const SGVec3d& linearVelocity,
const SGVec3d& angularVelocity)
{
// Do an euler step with the derivatives at mSimTime
_location.eulerStepBodyVelocities(dt, _linearBodyVelocity, _angularBodyVelocity);
_geodPosition = SGGeod::fromCart(_location.getPosition());
_horizontalLocalOrientation = SGQuatd::fromLonLat(_geodPosition);
// Store the new velocities for the next interval at mSimTim + dt
_linearBodyVelocity = linearVelocity;
_angularBodyVelocity = angularVelocity;
}
void
AIPhysics::advanceToLocation(const double& dt, const SGLocationd& location)
{
// At first we need to move along with the announced velocities, so:
// Do an euler step with the derivatives at mSimTime.
_location.eulerStepBodyVelocities(dt, _linearBodyVelocity, _angularBodyVelocity);
_geodPosition = SGGeod::fromCart(_location.getPosition());
_horizontalLocalOrientation = SGQuatd::fromLonLat(_geodPosition);
// Now compute velocities that will move to the desired position, orientation if the next
// advance method is called with the same dt value
SGVec3d positionDifference = location.getPosition() - _location.getPosition();
_linearBodyVelocity = (1/dt)*_location.getOrientation().transform(positionDifference);
_angularBodyVelocity = SGQuatd::forwardDifferenceVelocity(_location.getOrientation(), location.getOrientation(), dt);
}
} // namespace fgai