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flightgear/src/FDM/YASim/Model.cpp
2001-12-10 23:13:54 +00:00

351 lines
8.6 KiB
C++

#include <stdio.h>
#include "Atmosphere.hpp"
#include "Thruster.hpp"
#include "Math.hpp"
#include "RigidBody.hpp"
#include "Integrator.hpp"
#include "Propeller.hpp"
#include "PistonEngine.hpp"
#include "Gear.hpp"
#include "Surface.hpp"
#include "Glue.hpp"
#include "Model.hpp"
namespace yasim {
void printState(State* s)
{
State tmp = *s;
Math::vmul33(tmp.orient, tmp.v, tmp.v);
Math::vmul33(tmp.orient, tmp.acc, tmp.acc);
Math::vmul33(tmp.orient, tmp.rot, tmp.rot);
Math::vmul33(tmp.orient, tmp.racc, tmp.racc);
printf("\nNEW STATE (LOCAL COORDS)\n");
printf("pos: %10.2f %10.2f %10.2f\n", tmp.pos[0], tmp.pos[1], tmp.pos[2]);
printf("o: ");
int i;
for(i=0; i<3; i++) {
if(i != 0) printf(" ");
printf("%6.2f %6.2f %6.2f\n",
tmp.orient[3*i+0], tmp.orient[3*i+1], tmp.orient[3*i+2]);
}
printf("v: %6.2f %6.2f %6.2f\n", tmp.v[0], tmp.v[1], tmp.v[2]);
printf("acc: %6.2f %6.2f %6.2f\n", tmp.acc[0], tmp.acc[1], tmp.acc[2]);
printf("rot: %6.2f %6.2f %6.2f\n", tmp.rot[0], tmp.rot[1], tmp.rot[2]);
printf("rac: %6.2f %6.2f %6.2f\n", tmp.racc[0], tmp.racc[1], tmp.racc[2]);
}
Model::Model()
{
int i;
for(i=0; i<3; i++) _wind[i] = 0;
_integrator.setBody(&_body);
_integrator.setEnvironment(this);
// Default value of 30 Hz
_integrator.setInterval(1.0/30.0);
_agl = 0;
_crashed = false;
}
Model::~Model()
{
// FIXME: who owns these things? Need a policy
}
void Model::getThrust(float* out)
{
float tmp[3];
out[0] = out[1] = out[2] = 0;
int i;
for(i=0; i<_thrusters.size(); i++) {
Thruster* t = (Thruster*)_thrusters.get(i);
t->getThrust(tmp);
Math::add3(tmp, out, out);
}
}
void Model::initIteration()
{
// Precompute torque and angular momentum for the thrusters
int i;
for(i=0; i<3; i++)
_gyro[i] = _torque[i] = 0;
for(i=0; i<_thrusters.size(); i++) {
Thruster* t = (Thruster*)_thrusters.get(i);
// Get the wind velocity at the thruster location
float pos[3], v[3];
t->getPosition(pos);
localWind(pos, _s, v);
t->setWind(v);
t->setAir(_pressure, _temp);
t->integrate(_integrator.getInterval());
t->getTorque(v);
Math::add3(v, _torque, _torque);
t->getGyro(v);
Math::add3(v, _gyro, _gyro);
}
}
void Model::iterate()
{
initIteration();
_body.recalc(); // FIXME: amortize this, somehow
_integrator.calcNewInterval();
}
bool Model::isCrashed()
{
return _crashed;
}
void Model::setCrashed(bool crashed)
{
_crashed = crashed;
}
float Model::getAGL()
{
return _agl;
}
State* Model::getState()
{
return _s;
}
void Model::setState(State* s)
{
_integrator.setState(s);
_s = _integrator.getState();
}
RigidBody* Model::getBody()
{
return &_body;
}
Integrator* Model::getIntegrator()
{
return &_integrator;
}
Surface* Model::getSurface(int handle)
{
return (Surface*)_surfaces.get(handle);
}
int Model::addThruster(Thruster* t)
{
return _thrusters.add(t);
}
int Model::numThrusters()
{
return _thrusters.size();
}
Thruster* Model::getThruster(int handle)
{
return (Thruster*)_thrusters.get(handle);
}
void Model::setThruster(int handle, Thruster* t)
{
_thrusters.set(handle, t);
}
int Model::addSurface(Surface* surf)
{
return _surfaces.add(surf);
}
int Model::addGear(Gear* gear)
{
return _gears.add(gear);
}
void Model::setGroundEffect(float* pos, float span, float mul)
{
Math::set3(pos, _wingCenter);
_groundEffectSpan = span;
_groundEffect = mul;
}
// The first three elements are a unit vector pointing from the global
// origin to the plane, the final element is the distance from the
// origin (the radius of the earth, in most implementations). So
// (v dot _ground)-_ground[3] gives the distance AGL.
void Model::setGroundPlane(double* planeNormal, double fromOrigin)
{
int i;
for(i=0; i<3; i++) _ground[i] = planeNormal[i];
_ground[3] = fromOrigin;
}
void Model::setAir(float pressure, float temp)
{
_pressure = pressure;
_temp = temp;
_rho = Atmosphere::calcDensity(pressure, temp);
}
void Model::setWind(float* wind)
{
Math::set3(wind, _wind);
}
void Model::calcForces(State* s)
{
// Add in the pre-computed stuff. These values aren't part of the
// Runge-Kutta integration (they don't depend on position or
// velocity), and are therefore constant across the four calls to
// calcForces. They get computed before we begin the integration
// step.
_body.setGyro(_gyro);
_body.addTorque(_torque);
int i;
for(i=0; i<_thrusters.size(); i++) {
Thruster* t = (Thruster*)_thrusters.get(i);
float thrust[3], pos[3];
t->getThrust(thrust);
t->getPosition(pos);
_body.addForce(pos, thrust);
}
// Gravity, convert to a force, then to local coordinates
float grav[3];
Glue::geodUp(s->pos, grav);
Math::mul3(-9.8 * _body.getTotalMass(), grav, grav);
Math::vmul33(s->orient, grav, grav);
_body.addForce(grav);
// Do each surface, remembering that the local velocity at each
// point is different due to rotation.
float faero[3];
faero[0] = faero[1] = faero[2] = 0;
for(i=0; i<_surfaces.size(); i++) {
Surface* sf = (Surface*)_surfaces.get(i);
// Vsurf = wind - velocity + (rot cross (cg - pos))
float vs[3], pos[3];
sf->getPosition(pos);
localWind(pos, s, vs);
float force[3], torque[3];
sf->calcForce(vs, _rho, force, torque);
Math::add3(faero, force, faero);
_body.addForce(pos, force);
_body.addTorque(torque);
}
// Get a ground plane in local coordinates. The first three
// elements are the normal vector, the final one is the distance
// from the local origin along that vector to the ground plane
// (negative for objects "above" the ground)
float ground[4];
ground[3] = localGround(s, ground);
// Account for ground effect by multiplying the vertical force
// component by an amount linear with the fraction of the wingspan
// above the ground.
float dist = ground[4] - Math::dot3(ground, _wingCenter);
if(dist > 0 && dist < _groundEffectSpan) {
float fz = Math::dot3(faero, ground);
Math::mul3(fz * _groundEffect * dist/_groundEffectSpan,
ground, faero);
_body.addForce(faero);
}
// Convert the velocity and rotation vectors to local coordinates
float lrot[3], lv[3];
Math::vmul33(s->orient, s->rot, lrot);
Math::vmul33(s->orient, s->v, lv);
// The landing gear
for(i=0; i<_gears.size(); i++) {
float force[3], contact[3];
Gear* g = (Gear*)_gears.get(i);
g->calcForce(&_body, lv, lrot, ground);
g->getForce(force, contact);
_body.addForce(contact, force);
}
}
void Model::newState(State* s)
{
_s = s;
//printState(s);
// Some simple collision detection
float min = 1e8;
float ground[4], pos[3], cmpr[3];
ground[3] = localGround(s, ground);
int i;
for(i=0; i<_gears.size(); i++) {
Gear* g = (Gear*)_gears.get(i);
// Get the point of ground contact
g->getPosition(pos);
g->getCompression(cmpr);
Math::mul3(g->getCompressFraction(), cmpr, cmpr);
Math::add3(cmpr, pos, pos);
float dist = ground[3] - Math::dot3(pos, ground);
// Find the lowest one
if(dist < min)
min = dist;
}
_agl = min;
if(_agl < -1) // Allow for some integration slop
_crashed = true;
}
// Returns a unit "down" vector for the ground in out, and the
// distance from the local origin to the ground as the return value.
// So for a given position V, "dist - (V dot out)" will be the height
// AGL.
float Model::localGround(State* s, float* out)
{
// Get the ground's "down" vector, this can be in floats, because
// we don't need positioning accuracy. The direction has plenty
// of accuracy after truncation.
out[0] = -(float)_ground[0];
out[1] = -(float)_ground[1];
out[2] = -(float)_ground[2];
Math::vmul33(s->orient, out, out);
// The distance from the ground to the Aircraft's origin:
double dist = (s->pos[0]*_ground[0]
+ s->pos[1]*_ground[1]
+ s->pos[2]*_ground[2] - _ground[3]);
return (float)dist;
}
// Calculates the airflow direction at the given point and for the
// specified aircraft velocity.
void Model::localWind(float* pos, State* s, float* out)
{
// Most of the input is in global coordinates. Fix that.
float lwind[3], lrot[3], lv[3];
Math::vmul33(s->orient, _wind, lwind);
Math::vmul33(s->orient, s->rot, lrot);
Math::vmul33(s->orient, s->v, lv);
_body.pointVelocity(pos, lrot, out); // rotational velocity
Math::mul3(-1, out, out); // (negated)
Math::add3(lwind, out, out); // + wind
Math::sub3(out, lv, out); // - velocity
}
}; // namespace yasim