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flightgear/src/Navaids/routePath.cxx
2022-10-20 20:29:11 +08:00

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// routePath.hxx - compute data about planned route
//
// Copyright (C) 2018 James Turner <james@flightgear.org>
// 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.
#include "config.h"
#include <algorithm>
#include <Navaids/routePath.hxx>
#include <simgear/structure/exception.hxx>
#include <simgear/magvar/magvar.hxx>
#include <simgear/timing/sg_time.hxx>
#include <Main/globals.hxx>
#include <Airports/runways.hxx>
#include <Navaids/waypoint.hxx>
#include <Navaids/FlightPlan.hxx>
#include <Navaids/positioned.hxx>
#include <Aircraft/AircraftPerformance.hxx>
namespace flightgear {
// implementation of
// http://williams.best.vwh.net/avform.htm#Intersection
bool geocRadialIntersection(const SGGeoc& a, double r1, const SGGeoc& b, double r2, SGGeoc& result)
{
double crs13 = r1 * SG_DEGREES_TO_RADIANS;
double crs23 = r2 * SG_DEGREES_TO_RADIANS;
double dst12 = SGGeodesy::distanceRad(a, b);
//IF sin(lon2-lon1)<0
// crs12=acos((sin(lat2)-sin(lat1)*cos(dst12))/(sin(dst12)*cos(lat1)))
// crs21=2.*pi-acos((sin(lat1)-sin(lat2)*cos(dst12))/(sin(dst12)*cos(lat2)))
// ELSE
// crs12=2.*pi-acos((sin(lat2)-sin(lat1)*cos(dst12))/(sin(dst12)*cos(lat1)))
// crs21=acos((sin(lat1)-sin(lat2)*cos(dst12))/(sin(dst12)*cos(lat2)))
// ENDIF
double sinLat1 = sin(a.getLatitudeRad());
double cosLat1 = cos(a.getLatitudeRad());
double sinDst12 = sin(dst12);
double cosDst12 = cos(dst12);
double crs12 = SGGeodesy::courseRad(a, b),
crs21 = SGGeodesy::courseRad(b, a);
// normalise to -pi .. pi range
double ang1 = SGMiscd::normalizeAngle(crs13-crs12);
double ang2 = SGMiscd::normalizeAngle(crs21-crs23);
if ((sin(ang1) == 0.0) && (sin(ang2) == 0.0)) {
SG_LOG(SG_INSTR, SG_INFO, "geocRadialIntersection: infinity of intersections");
return false;
}
if ((sin(ang1)*sin(ang2))<0.0) {
// SG_LOG(SG_INSTR, SG_INFO, "geocRadialIntersection: intersection ambiguous:"
// << ang1 << " " << ang2 << " sin1 " << sin(ang1) << " sin2 " << sin(ang2));
return false;
}
ang1 = fabs(ang1);
ang2 = fabs(ang2);
//ang3=acos(-cos(ang1)*cos(ang2)+sin(ang1)*sin(ang2)*cos(dst12))
//dst13=atan2(sin(dst12)*sin(ang1)*sin(ang2),cos(ang2)+cos(ang1)*cos(ang3))
//lat3=asin(sin(lat1)*cos(dst13)+cos(lat1)*sin(dst13)*cos(crs13))
//lon3=mod(lon1-dlon+pi,2*pi)-pi
double ang3 = acos(-cos(ang1) * cos(ang2) + sin(ang1) * sin(ang2) * cosDst12);
double dst13 = atan2(sinDst12 * sin(ang1) * sin(ang2), cos(ang2) + cos(ang1)*cos(ang3));
SGGeoc pt3;
SGGeodesy::advanceRadM(a, crs13, dst13 * SG_RAD_TO_NM * SG_NM_TO_METER, pt3);
double lat3 = asin(sinLat1 * cos(dst13) + cosLat1 * sin(dst13) * cos(crs13));
//dlon=atan2(sin(crs13)*sin(dst13)*cos(lat1),cos(dst13)-sin(lat1)*sin(lat3))
double dlon = atan2(sin(crs13)*sin(dst13)*cosLat1, cos(dst13)- (sinLat1 * sin(lat3)));
double lon3 = SGMiscd::normalizeAngle(-a.getLongitudeRad()-dlon);
result = SGGeoc::fromRadM(-lon3, lat3, a.getRadiusM());
//result = pt3;
return true;
}
}
using namespace flightgear;
// implement Point(s) known distance from a great circle
static double sqr(const double x)
{
return x * x;
}
// http://williams.best.vwh.net/avform.htm#POINTDME
double pointsKnownDistanceFromGC(const SGGeoc& a, const SGGeoc&b, const SGGeoc& d, double dist)
{
double A = SGGeodesy::courseRad(a, d) - SGGeodesy::courseRad(a, b);
double bDist = SGGeodesy::distanceRad(a, d);
// r=(cos(b)^2+sin(b)^2*cos(A)^2)^(1/2)
double r = pow(sqr(cos(bDist)) + sqr(sin(bDist)) * sqr(cos(A)), 0.5);
double p = atan2(sin(bDist)*cos(A), cos(bDist));
if (sqr(cos(dist)) > sqr(r)) {
SG_LOG(SG_NAVAID, SG_INFO, "pointsKnownDistanceFromGC, no points exist");
return -1.0;
}
double dp1 = p + acos(cos(dist)/r);
double dp2 = p - acos(cos(dist)/r);
double dp1Nm = fabs(dp1 * SG_RAD_TO_NM);
double dp2Nm = fabs(dp2 * SG_RAD_TO_NM);
return SGMiscd::min(dp1Nm, dp2Nm);
}
// http://williams.best.vwh.net/avform.htm#Int
double latitudeForGCLongitude(const SGGeoc& a, const SGGeoc& b, double lon)
{
#if 0
Intermediate points {lat,lon} lie on the great circle connecting points 1 and 2 when:
lat=atan((sin(lat1)*cos(lat2)*sin(lon-lon2)
-sin(lat2)*cos(lat1)*sin(lon-lon1))/(cos(lat1)*cos(lat2)*sin(lon1-lon2)))
#endif
double lonDiff = a.getLongitudeRad() - b.getLongitudeRad();
double cosLat1 = cos(a.getLatitudeRad()),
cosLat2 = cos(b.getLatitudeRad());
double x = sin(a.getLatitudeRad()) * cosLat2 * sin(lon - b.getLongitudeRad());
double y = sin(b.getLatitudeRad()) * cosLat1 * sin(lon - a.getLongitudeRad());
double denom = cosLat1 * cosLat2 * sin(lonDiff);
double lat = atan((x - y) / denom);
return lat;
}
static double magVarFor(const SGGeod& geod)
{
double jd = globals->get_time_params()->getJD();
return sgGetMagVar(geod, jd) * SG_RADIANS_TO_DEGREES;
}
SGGeod turnCenterOverflight(const SGGeod& pt, double inHeadingDeg,
double turnAngleDeg, double turnRadiusM)
{
double p = copysign(90.0, turnAngleDeg);
return SGGeodesy::direct(pt, inHeadingDeg + p, turnRadiusM);
}
SGGeod turnCenterFlyBy(const SGGeod& pt, double inHeadingDeg,
double turnAngleDeg, double turnRadiusM)
{
double halfAngle = turnAngleDeg * 0.5;
double turnCenterOffset = turnRadiusM / cos(halfAngle * SG_DEGREES_TO_RADIANS);
double p = copysign(90.0, turnAngleDeg);
return SGGeodesy::direct(pt, inHeadingDeg + halfAngle + p, turnCenterOffset);
}
SGGeod turnCenterFromExit(const SGGeod& pt, double outHeadingDeg,
double turnAngleDeg, double turnRadiusM)
{
double p = copysign(90.0, turnAngleDeg);
return SGGeodesy::direct(pt, outHeadingDeg + p, turnRadiusM);
}
struct TurnInfo
{
SGGeod turnCenter;
double inboundCourseDeg = 0.0;
double turnAngleDeg = 0.0;
bool valid = false;
};
/**
* given a turn exit position and heading, and an arbitrary origin position,
* compute the turn center / angle that matches. Certain configurations may
* fail, especially if the origin is less than two turn radii from the exit pos.
*/
TurnInfo turnCenterAndAngleFromExit(const SGGeod& pt, double outHeadingDeg,
double turnRadiusM, const SGGeod&origin)
{
double bearingToExit = SGGeodesy::courseDeg(origin, pt);
// not the final turn angle, but we need to know which side of the
// exit course we're on, to decide if it's a left-hand or right-hand turn
double turnAngle = outHeadingDeg - bearingToExit;
SG_NORMALIZE_RANGE(turnAngle, -180.0, 180.0);
double p = copysign(90.0, turnAngle);
TurnInfo r;
r.turnCenter = SGGeodesy::direct(pt, outHeadingDeg + p, turnRadiusM);
double courseToTC, distanceToTC, az2;
SGGeodesy::inverse(origin, r.turnCenter, courseToTC, az2, distanceToTC);
if (distanceToTC < turnRadiusM) {
SG_LOG(SG_NAVAID, SG_WARN, "turnCenterAndAngleFromExit: origin point too close to turn center");
return r;
}
// find additional course angle away from the exit pos to intersect
// the turn circle.
double theta = asin(turnRadiusM / distanceToTC) * SG_RADIANS_TO_DEGREES;
// invert angle sign so we increase the turn angle
theta = -copysign(theta, turnAngle);
r.inboundCourseDeg = courseToTC + theta;
SG_NORMALIZE_RANGE(r.inboundCourseDeg, 0.0, 360.0);
// turn angle must have same direction (sign) as turnAngle above, even if
// the turn radius means the sign would cross over (happens if origin point
// is close by
r.turnAngleDeg = outHeadingDeg - r.inboundCourseDeg;
if (r.turnAngleDeg > 0.0) {
if (turnAngle < 0.0) r.turnAngleDeg -= 360.0;
} else {
if (turnAngle > 0.0) r.turnAngleDeg += 360.0;
}
r.valid = true;
return r;
}
class WayptData;
using WayptDataVec = std::vector<WayptData>;
using WpDataIt = WayptDataVec::iterator;
class WayptData
{
public:
explicit WayptData(WayptRef w) :
wpt(w),
hasEntry(false),
posValid(false),
legCourseValid(false),
skipped(false),
turnEntryAngle(0.0),
turnExitAngle(0.0),
turnRadius(0.0),
legCourseTrue(0.0),
pathDistanceM(0.0),
turnPathDistanceM(0.0),
overflightCompensationAngle(0.0),
flyOver(w->flag(WPT_OVERFLIGHT))
{
}
void initPass0()
{
const std::string& ty(wpt->type());
if (wpt->flag(WPT_DYNAMIC)) {
// presumption is that we always overfly such a waypoint
if (ty == "hdgToAlt") {
flyOver = true;
}
} else if (ty == "discontinuity") {
} else {
pos = wpt->position();
posValid = true;
} // of static waypt
}
/**
* test if course of this leg can be adjusted or is contrained to an exact value
*/
bool isCourseConstrained() const
{
const std::string& ty(wpt->type());
return (ty == "hdgToAlt") || (ty == "radialIntercept") || (ty == "dmeIntercept");
}
// compute leg courses for all static legs (both ends are fixed)
void initPass1(const WayptData* previous, WayptData* next)
{
const auto ty = wpt->type();
if ((ty == "vectors") || (ty == "discontinuity")) {
// relying on the fact vectors will be followed by a static fix/wpt
if (next && next->posValid) {
posValid = true;
pos = next->pos;
}
}
const bool previousPosValid = previous && previous->posValid;
if (ty == "via") {
// even though both ends may be known, we don't
// want to compute a leg course for a VIA
} else if (posValid && !legCourseValid && previousPosValid) {
const auto prevWP = previous->wpt;
// check for duplicate points now
if (prevWP->matches(wpt)) {
skipped = true;
}
// we can compute leg course now
if (prevWP->type() == "runway") {
// use the runway departure end pos
FGRunway* rwy = static_cast<RunwayWaypt*>(prevWP.get())->runway();
legCourseTrue = SGGeodesy::courseDeg(rwy->end(), pos);
} else if (ty == "discontinuity") {
// we want to keep the path across DISCONs sharp (no turn entry/exit)
// so we keep the leg course invalid, even though we actually
// could compute it
} else if (ty != "runway") {
// need to wait to compute runway leg course
legCourseTrue = SGGeodesy::courseDeg(previous->pos, pos);
legCourseValid = true;
}
} // of not a VIA
}
void computeLegCourse(const WayptData* previous, double radiusM)
{
if (legCourseValid) {
return;
}
if ((wpt->type() == "via") || (wpt->type() == "discontinuty"))
{
// do nothing, we can't compute a valid leg course for these types
// we'll generate sharp turns in the path but that's no problem.
return;
}
if (!previous || !previous->posValid) {
// all the cases below assume previous pas exists and has a valid position
SG_LOG(SG_NAVAID, SG_WARN, "RoutePath: Asked to compute leg course, but, previous is invalid");
return;
}
if (wpt->type() == "runway") {
FGRunway* rwy = static_cast<RunwayWaypt*>(wpt.get())->runway();
flyOver = true;
TurnInfo ti = turnCenterAndAngleFromExit(rwy->threshold(),
rwy->headingDeg(),
radiusM, previous->pos);
if (ti.valid) {
legCourseTrue = ti.inboundCourseDeg;
turnEntryAngle = ti.turnAngleDeg;
turnEntryCenter = ti.turnCenter;
turnRadius = radiusM;
hasEntry = true;
turnEntryPos = pointOnEntryTurnFromHeading(ti.inboundCourseDeg);
} else {
// couldn't compute entry, never mind
legCourseTrue = SGGeodesy::courseDeg(previous->pos, rwy->threshold());
}
legCourseValid = true;
return;
}
SGGeod previousPos = previous->pos;
// use correct location for runway, otherwise use threshold
// and get weird courses
if (previous->wpt->type() == "runway") {
FGRunway* rwy = static_cast<RunwayWaypt*>(previous->wpt.get())->runway();
previousPos = rwy->end();
}
if (posValid) {
legCourseTrue = SGGeodesy::courseDeg(previousPos, pos);
legCourseValid = true;
} else if (isCourseConstrained()) {
double magVar = magVarFor(previousPos);
legCourseTrue = wpt->headingRadialDeg() + magVar;
legCourseValid = true;
} // of pos not valid
}
SGGeod pointOnEntryTurnFromHeading(double headingDeg) const
{
assert(hasEntry);
double p = copysign(90.0, turnEntryAngle);
return SGGeodesy::direct(turnEntryCenter, headingDeg - p, turnRadius);
}
SGGeod pointOnExitTurnFromHeading(double headingDeg) const
{
double p = copysign(90.0, turnExitAngle);
return SGGeodesy::direct(turnExitCenter, headingDeg - p, turnRadius);
}
double pathDistanceForTurnAngle(double angleDeg) const
{
return turnRadius * fabs(angleDeg) * SG_DEGREES_TO_RADIANS;
}
void computeTurn(double radiusM, bool constrainLegCourse, double maxFlyByTurnAngleDeg, WayptData& next)
{
assert(!skipped);
assert(next.legCourseValid);
bool isRunway = (wpt->type() == "runway");
if (legCourseValid) {
if (isRunway) {
FGRunway* rwy = static_cast<RunwayWaypt*>(wpt.get())->runway();
turnExitAngle = next.legCourseTrue - rwy->headingDeg();
} else {
turnExitAngle = next.legCourseTrue - legCourseTrue;
}
} else {
// happens for first leg
if (isRunway) {
legCourseValid = true;
FGRunway* rwy = static_cast<RunwayWaypt*>(wpt.get())->runway();
turnExitAngle = next.legCourseTrue - rwy->headingDeg();
legCourseTrue = rwy->headingDeg();
flyOver = true;
// fall through
} else {
legCourseValid = true;
legCourseTrue = next.legCourseTrue;
turnExitAngle = 0.0;
turnExitPos = pos;
flyOver = true;
return;
}
}
SG_NORMALIZE_RANGE(turnExitAngle, -180.0, 180.0);
turnRadius = radiusM;
if (!flyOver && fabs(turnExitAngle) > maxFlyByTurnAngleDeg) {
// flyBy logic blows up for sharp turns - due to the tan() term
// heading towards infinity. By converting to flyOver we do something
// closer to what was requested. This matches logic in the RNAV
// Leg controller
flyOver = true;
}
if (flyOver) {
if (isRunway) {
FGRunway* rwy = static_cast<RunwayWaypt*>(wpt.get())->runway();
turnExitCenter = turnCenterOverflight(rwy->end(), rwy->headingDeg(), turnExitAngle, turnRadius);
} else {
turnEntryPos = pos;
turnExitCenter = turnCenterOverflight(pos, legCourseTrue, turnExitAngle, turnRadius);
}
turnExitPos = pointOnExitTurnFromHeading(next.legCourseTrue);
if (!next.wpt->flag(WPT_DYNAMIC)) {
// distance perpendicular to next leg course, after turning
// through turnAngle
double xtk = turnRadius * (1 - cos(turnExitAngle * SG_DEGREES_TO_RADIANS));
if (constrainLegCourse || next.isCourseConstrained()) {
// next leg course is constrained. We need to swing back onto the
// desired course, using a compensation turn
// compensation angle to turn back on course
double theta = acos((turnRadius - (xtk * 0.5)) / turnRadius) * SG_RADIANS_TO_DEGREES;
theta = copysign(theta, turnExitAngle);
turnExitAngle += theta;
double p = copysign(90, turnExitAngle);
const double offsetAngle = legCourseTrue + turnExitAngle - p;
SGGeod tc2 = SGGeodesy::direct(turnExitCenter,
offsetAngle,
turnRadius * 2.0);
turnExitPos = SGGeodesy::direct(tc2, next.legCourseTrue + p , turnRadius);
overflightCompensationAngle = -theta;
// sign of angles will differ, so compute distances seperately
turnPathDistanceM = pathDistanceForTurnAngle(turnExitAngle) +
pathDistanceForTurnAngle(overflightCompensationAngle);
} else {
// next leg course can be adjusted. increase the turn angle
// and modify the next leg's course accordingly.
// hypotenuse of triangle, opposite edge has length turnRadius
double distAlongPath = std::min(1.0, sin(fabs(turnExitAngle) * SG_DEGREES_TO_RADIANS)) * turnRadius;
double nextLegDistance = SGGeodesy::distanceM(pos, next.pos) - distAlongPath;
double increaseAngle = atan2(xtk, nextLegDistance) * SG_RADIANS_TO_DEGREES;
increaseAngle = copysign(increaseAngle, turnExitAngle);
turnExitAngle += increaseAngle;
turnExitPos = pointOnExitTurnFromHeading(legCourseTrue + turnExitAngle);
// modify next leg course
next.legCourseTrue = SGGeodesy::courseDeg(turnExitPos, next.pos);
turnPathDistanceM = pathDistanceForTurnAngle(turnExitAngle);
} // of next leg isn't course constrained
} else {
// next point is dynamic
// no compensation needed
turnPathDistanceM = pathDistanceForTurnAngle(turnExitAngle);
}
} else {
hasEntry = true;
turnEntryCenter = turnCenterFlyBy(pos, legCourseTrue, turnExitAngle, turnRadius);
turnExitAngle = turnExitAngle * 0.5;
turnEntryAngle = turnExitAngle;
turnExitCenter = turnEntryCenter; // important that these match
turnEntryPos = pointOnEntryTurnFromHeading(legCourseTrue);
turnExitPos = pointOnExitTurnFromHeading(next.legCourseTrue);
turnPathDistanceM = pathDistanceForTurnAngle(turnEntryAngle);
}
}
double turnDistanceM() const
{
return turnPathDistanceM;
}
void turnEntryPath(SGGeodVec& path) const
{
if (!hasEntry || fabs(turnEntryAngle) < 0.5 ) {
path.push_back(pos);
return;
}
int steps = std::max(SGMiscd::roundToInt(fabs(turnEntryAngle) / 3.0), 1);
double stepIncrement = turnEntryAngle / steps;
double h = legCourseTrue;
for (int s=0; s<steps; ++s) {
path.push_back(pointOnEntryTurnFromHeading(h));
h += stepIncrement;
}
}
void turnExitPath(SGGeodVec& path) const
{
if (fabs(turnExitAngle) < 0.5) {
path.push_back(turnExitPos);
return;
}
int steps = std::max(SGMiscd::roundToInt(fabs(turnExitAngle) / 3.0), 1);
double stepIncrement = turnExitAngle / steps;
// initial exit heading
double h = legCourseTrue + (flyOver ? 0.0 : turnEntryAngle);
if (wpt->type() == "runway") {
FGRunway* rwy = static_cast<RunwayWaypt*>(wpt.get())->runway();
h = rwy->headingDeg();
}
for (int s=0; s<steps; ++s) {
path.push_back(pointOnExitTurnFromHeading(h));
h += stepIncrement;
}
// we can use an exact check on the compensation angle, because we
// initialise it directly. Depending on the next element we might be
// doing compensation or adjusting the next leg's course; if we did
// adjust the course everything 'just works' above.
if (flyOver && (overflightCompensationAngle != 0.0)) {
// skew by compensation angle back
steps = std::max(SGMiscd::roundToInt(fabs(overflightCompensationAngle) / 3.0), 1);
// step in opposite direction to the turn angle to swing back onto
// the next leg course
stepIncrement = overflightCompensationAngle / steps;
SGGeod p = path.back();
double stepDist = (fabs(stepIncrement) / 360.0) * SGMiscd::twopi() * turnRadius;
for (int s=0; s<steps; ++s) {
h += stepIncrement;
p = SGGeodesy::direct(p, h, stepDist);
path.push_back(p);
}
} // of overflight compensation turn
}
SGGeod pointAlongExitPath(double distanceM) const
{
double basicTurnDistance = pathDistanceForTurnAngle(turnExitAngle);
if (distanceM > basicTurnDistance) {
assert(flyOver);
assert(overflightCompensationAngle != 0.0);
double p = copysign(90, turnExitAngle);
double distanceAlongCompensationTurn = distanceM - basicTurnDistance;
double theta = (distanceAlongCompensationTurn / turnRadius) * SG_RADIANS_TO_DEGREES;
// compute the compensation turn center - twice the turn radius
// from turnCenter
SGGeod tc2 = SGGeodesy::direct(turnExitCenter,
legCourseTrue + turnExitAngle - p,
turnRadius * 2.0);
theta = copysign(theta, overflightCompensationAngle);
return SGGeodesy::direct(tc2,
legCourseTrue + turnExitAngle + theta + p, turnRadius);
}
double theta = (distanceM / turnRadius) * SG_RADIANS_TO_DEGREES;
theta = copysign(theta, turnExitAngle);
double inboundCourse = legCourseTrue + (flyOver ? 0.0 : turnExitAngle);
return pointOnExitTurnFromHeading(inboundCourse + theta);
}
SGGeod pointAlongEntryPath(double distanceM) const
{
assert(hasEntry);
double theta = (distanceM / turnRadius) * SG_RADIANS_TO_DEGREES;
theta = copysign(theta, turnEntryAngle);
return pointOnEntryTurnFromHeading(legCourseTrue + theta);
}
WayptRef wpt;
bool hasEntry, posValid, legCourseValid, skipped;
SGGeod pos, turnEntryPos, turnExitPos, turnEntryCenter, turnExitCenter;
double turnEntryAngle, turnExitAngle, turnRadius, legCourseTrue;
double pathDistanceM;
double turnPathDistanceM; // for flyBy, this is half the distance; for flyOver it's the complete distance
double overflightCompensationAngle;
bool flyOver;
};
bool isDescentWaypoint(const WayptRef& wpt)
{
return (wpt->flag(WPT_APPROACH) && !wpt->flag(WPT_MISS)) || wpt->flag(WPT_ARRIVAL);
}
class RoutePath::RoutePathPrivate
{
public:
WayptDataVec waypoints;
AircraftPerformance perf;
bool constrainLegCourses;
double maxFlyByTurnAngleDeg = 90.0;
void computeDynamicPosition(int index)
{
auto previous(previousValidWaypoint(index));
if ((previous == waypoints.end()) || !previous->posValid) {
SG_LOG(SG_NAVAID, SG_WARN, "couldn't compute position for dynamic waypoint: no preceeding valid waypoint");
return;
}
WayptRef wpt = waypoints[index].wpt;
const std::string& ty(wpt->type());
if (ty == "hdgToAlt") {
HeadingToAltitude* h = (HeadingToAltitude*)wpt.get();
double altFt = computeVNAVAltitudeFt(index - 1);
double distanceM = perf.distanceNmBetween(altFt, h->altitudeFt()) * SG_NM_TO_METER;
double hdg = h->headingDegMagnetic() + magVarFor(previous->pos);
waypoints[index].pos = SGGeodesy::direct(previous->turnExitPos, hdg, distanceM);
waypoints[index].posValid = true;
} else if (ty == "radialIntercept") {
// start from previous.turnExit
RadialIntercept* i = (RadialIntercept*)wpt.get();
SGGeoc prevGc = SGGeoc::fromGeod(previous->turnExitPos);
SGGeoc navid = SGGeoc::fromGeod(wpt->position());
SGGeoc rGc;
double magVar = magVarFor(previous->pos);
double radial = i->radialDegMagnetic() + magVar;
double track = i->courseDegMagnetic() + magVar;
bool ok = geocRadialIntersection(prevGc, track, navid, radial, rGc);
if (!ok) {
// try pulling backward along the radial in case we're too close.
// suggests bad procedure construction if this is happening!
SGGeoc navidAdjusted = SGGeodesy::advanceDegM(navid, radial, -10 * SG_NM_TO_METER);
// try again
ok = geocRadialIntersection(prevGc, track, navidAdjusted, radial, rGc);
if (!ok) {
SG_LOG(SG_NAVAID, SG_WARN, "couldn't compute interception for radial:" << previous->turnExitPos << " / " << track << "/" << wpt->position() << "/" << radial);
waypoints[index].pos = wpt->position(); // horrible fallback
} else {
waypoints[index].pos = SGGeod::fromGeoc(rGc);
}
} else {
waypoints[index].pos = SGGeod::fromGeoc(rGc);
}
waypoints[index].posValid = true;
} else if (ty == "dmeIntercept") {
DMEIntercept* di = (DMEIntercept*)wpt.get();
SGGeoc prevGc = SGGeoc::fromGeod(previous->turnExitPos);
SGGeoc navid = SGGeoc::fromGeod(wpt->position());
double distRad = di->dmeDistanceNm() * SG_NM_TO_RAD;
SGGeoc rGc;
double crs = di->courseDegMagnetic() + magVarFor(wpt->position());
SGGeoc bPt = SGGeodesy::advanceDegM(prevGc, crs, 1e5);
double dNm = pointsKnownDistanceFromGC(prevGc, bPt, navid, distRad);
if (dNm < 0.0) {
SG_LOG(SG_NAVAID, SG_WARN, "dmeIntercept failed");
waypoints[index].pos = wpt->position(); // horrible fallback
} else {
waypoints[index].pos = SGGeodesy::direct(previous->turnExitPos, crs, dNm * SG_NM_TO_METER);
}
waypoints[index].posValid = true;
} else if (ty == "vectors") {
waypoints[index].legCourseTrue = SGGeodesy::courseDeg(previous->turnExitPos, waypoints[index].pos);
waypoints[index].legCourseValid = true;
// no turn data
}
}
double computeVNAVAltitudeFt(int index)
{
WayptRef w = waypoints[index].wpt;
if ((w->flag(WPT_APPROACH) && !w->flag(WPT_MISS)) || w->flag(WPT_ARRIVAL)) {
// descent
int next = findNextKnownAltitude(index);
if (next < 0) {
return 0.0;
}
double fixedAlt = altitudeForIndex(next);
double distanceM = distanceBetweenIndices(index, next);
return perf.computePreviousAltitude(distanceM, fixedAlt);
} else {
// climb
int prev = findPreceedingKnownAltitude(index);
if (prev < 0) {
return 0.0;
}
double fixedAlt = altitudeForIndex(prev);
double distanceM = distanceBetweenIndices(prev, index);
return perf.computeNextAltitude(distanceM, fixedAlt);
}
}
int findPreceedingKnownAltitude(int index) const
{
const WayptData& w(waypoints[index]);
if (w.wpt->altitudeRestriction() == RESTRICT_AT) {
return index;
}
// principal base case is runways.
const std::string& ty(w.wpt->type());
if (ty == "runway") {
return index; // runway always has a known elevation
}
if (index == 0) {
SG_LOG(SG_NAVAID, SG_WARN, "findPreceedingKnownAltitude: no preceding altitude value found");
return -1;
}
// recurse earlier in the route
return findPreceedingKnownAltitude(index - 1);
}
int findNextKnownAltitude(unsigned int index) const
{
if (index >= waypoints.size()) {
SG_LOG(SG_NAVAID, SG_WARN, "findNextKnownAltitude: no next altitude value found");
return -1;
}
const WayptData& w(waypoints[index]);
if (w.wpt->altitudeRestriction() == RESTRICT_AT) {
return index;
}
// principal base case is runways.
const std::string& ty(w.wpt->type());
if (ty == "runway") {
return index; // runway always has a known elevation
}
if (index == waypoints.size() - 1) {
SG_LOG(SG_NAVAID, SG_WARN, "findNextKnownAltitude: no next altitude value found");
return -1;
}
return findNextKnownAltitude(index + 1);
}
double altitudeForIndex(int index) const
{
const WayptData& w(waypoints[index]);
if (w.wpt->altitudeRestriction() != RESTRICT_NONE) {
return w.wpt->altitudeFt();
}
const std::string& ty(w.wpt->type());
if (ty == "runway") {
FGRunway* rwy = static_cast<RunwayWaypt*>(w.wpt.get())->runway();
return rwy->threshold().getElevationFt();
}
SG_LOG(SG_NAVAID, SG_WARN, "altitudeForIndex: waypoint has no explicit altitude");
return 0.0;
}
double distanceBetweenIndices(int from, int to) const
{
double total = 0.0;
for (int i=from+1; i<= to; ++i) {
total += waypoints[i].pathDistanceM;
}
return total;
}
WayptDataVec::iterator previousValidWaypoint(unsigned int index)
{
do {
if (index == 0) {
return waypoints.end();
}
--index;
} while (waypoints.at(index).skipped || (waypoints.at(index).wpt->type() == "discontinuity"));
return waypoints.begin() + index;
}
WayptDataVec::iterator previousValidWaypoint(WayptDataVec::iterator it)
{
return previousValidWaypoint(std::distance(waypoints.begin(), it));
}
WayptDataVec::iterator nextValidWaypoint(int index)
{
return nextValidWaypoint(waypoints.begin() + index);
}
WayptDataVec::iterator nextValidWaypoint(WayptDataVec::iterator it)
{
if (it == waypoints.end()) {
return it;
}
++it;
while ((it != waypoints.end()) && (it->skipped || (it->wpt->type() == "discontinuity"))) {
++it;
}
return it;
}
}; // of RoutePathPrivate class
RoutePath::RoutePath(const flightgear::FlightPlan* fp) :
d(new RoutePathPrivate)
{
for (int l=0; l<fp->numLegs(); ++l) {
WayptRef wpt = fp->legAtIndex(l)->waypoint();
if (!wpt) {
SG_LOG(SG_NAVAID, SG_DEV_ALERT, "Waypoint " << l << " of " << fp->numLegs() << "is NULL");
break;
}
d->waypoints.push_back(WayptData(wpt));
}
d->constrainLegCourses = fp->followLegTrackToFixes();
commonInit();
}
RoutePath::RoutePath(const RoutePath& other)
{
d.reset(new RoutePathPrivate(*other.d));
}
RoutePath& RoutePath::operator=(const RoutePath& other)
{
d.reset(new RoutePathPrivate(*other.d));
return *this;
}
RoutePath::~RoutePath()
{
}
void RoutePath::commonInit()
{
for (auto& w : d->waypoints) {
w.initPass0();
}
for (unsigned int i=1; i<d->waypoints.size(); ++i) {
WayptData* nextPtr = ((i + 1) < d->waypoints.size()) ? &d->waypoints[i+1] : nullptr;
auto prev = d->previousValidWaypoint(i);
WayptData* prevPtr = (prev == d->waypoints.end()) ? nullptr : &(*prev);
d->waypoints[i].initPass1(prevPtr, nextPtr);
}
for (unsigned int i=0; i<d->waypoints.size(); ++i) {
if (d->waypoints[i].skipped) {
continue;
}
double alt = 0.0; // FIXME
double radiusM = d->perf.turnRadiusMForAltitude(alt);
if (i > 0) {
auto prevIt = d->previousValidWaypoint(i);
WayptData* prevPtr = (prevIt == d->waypoints.end()) ? nullptr : &(*prevIt);
d->waypoints[i].computeLegCourse(prevPtr, radiusM);
d->computeDynamicPosition(i);
}
auto nextIt = d->nextValidWaypoint(i);
if (nextIt != d->waypoints.end()) {
nextIt->computeLegCourse(&(d->waypoints[i]), radiusM);
if (nextIt->legCourseValid) {
d->waypoints[i].computeTurn(radiusM, d->constrainLegCourses, d->maxFlyByTurnAngleDeg, *nextIt);
} else {
// next waypoint has indeterminate course. Let's create a sharp turn
// this can happen when the following point is ATC vectors, for example.
d->waypoints[i].turnEntryPos = d->waypoints[i].pos;
d->waypoints[i].turnExitPos = d->waypoints[i].pos;
}
} else {
// final waypt, fix up some data
d->waypoints[i].turnExitPos = d->waypoints[i].pos;
d->waypoints[i].turnEntryPos = d->waypoints[i].pos;
}
// now turn is computed, can resolve distances
d->waypoints[i].pathDistanceM = computeDistanceForIndex(i);
}
}
SGGeodVec RoutePath::pathForIndex(int index) const
{
if ((index < 0) || (index >= static_cast<int>(d->waypoints.size()))) {
return {};
}
const WayptData& w(d->waypoints[index]);
const std::string& ty(w.wpt->type());
SGGeodVec r;
if (d->waypoints[index].skipped) {
return {};
}
// don't show any path
if (w.wpt->flag(WPT_HIDDEN)) {
return {};
}
// also hide the path if the prev WP is hidden
auto prevIt = d->previousValidWaypoint(index);
if (prevIt != d->waypoints.end()) {
if (prevIt->wpt->flag(WPT_HIDDEN)) {
return {};
}
}
if (ty == "vectors") {
// ideally we'd show a stippled line to connect the route?
return {};
}
if (ty == "discontinuity") {
return {}; // no points for a discontinuity of course
}
if (ty == "via") {
return pathForVia(static_cast<Via*>(d->waypoints[index].wpt.get()), index);
}
if (prevIt != d->waypoints.end()) {
prevIt->turnExitPath(r);
SGGeod from = prevIt->turnExitPos,
to = w.turnEntryPos;
// compute rounding offset, we want to round towards the direction of travel
// which depends on the east/west sign of the longitude change
double lonDelta = to.getLongitudeDeg() - from.getLongitudeDeg();
if (fabs(lonDelta) > 0.5) {
interpolateGreatCircle(from, to, r);
}
} // of have previous waypoint
w.turnEntryPath(r);
// hold is the normal leg and then the hold waypoints as well
if (ty== "hold") {
const auto h = static_cast<Hold*>(d->waypoints[index].wpt.get());
const auto holdPath = pathForHold(h);
r.insert(r.end(), holdPath.begin(), holdPath.end());
}
if (ty == "runway") {
// runways get an extra point, at the end. this is particularly
// important so missed approach segments draw correctly
FGRunway* rwy = static_cast<RunwayWaypt*>(w.wpt.get())->runway();
r.push_back(rwy->end());
}
return r;
}
void RoutePath::interpolateGreatCircle(const SGGeod& aFrom, const SGGeod& aTo, SGGeodVec& r) const
{
SGGeoc gcFrom = SGGeoc::fromGeod(aFrom),
gcTo = SGGeoc::fromGeod(aTo);
double lonDelta = gcTo.getLongitudeRad() - gcFrom.getLongitudeRad();
if (fabs(lonDelta) < 1e-3) {
return;
}
lonDelta = SGMiscd::normalizeAngle(lonDelta);
int steps = static_cast<int>(fabs(lonDelta) * SG_RADIANS_TO_DEGREES * 2);
double lonStep = (lonDelta / steps);
double lon = gcFrom.getLongitudeRad() + lonStep;
for (int s=0; s < (steps - 1); ++s) {
lon = SGMiscd::normalizeAngle(lon);
double lat = latitudeForGCLongitude(gcFrom, gcTo, lon);
r.push_back(SGGeod::fromGeoc(SGGeoc::fromRadM(lon, lat, SGGeodesy::EQURAD)));
//SG_LOG(SG_GENERAL, SG_INFO, "lon:" << lon * SG_RADIANS_TO_DEGREES << " gives lat " << lat * SG_RADIANS_TO_DEGREES);
lon += lonStep;
}
}
SGGeod RoutePath::positionForIndex(int index) const
{
if ((index < 0) || (index >= static_cast<int>(d->waypoints.size()))) {
return {};
}
return d->waypoints[index].pos;
}
SGGeodVec RoutePath::pathForVia(Via* via, int index) const
{
// previous waypoint must be valid for a VIA
auto prevIt = d->previousValidWaypoint(index);
if (prevIt == d->waypoints.end()) {
return SGGeodVec();
}
WayptVec enrouteWaypoints = via->expandToWaypoints(prevIt->wpt);
SGGeodVec r;
WayptVec::const_iterator it;
SGGeod legStart = prevIt->wpt->position();
for (it = enrouteWaypoints.begin(); it != enrouteWaypoints.end(); ++it) {
// interpolate directly into the result vector
interpolateGreatCircle(legStart, (*it)->position(), r);
legStart = (*it)->position();
}
return r;
}
SGGeodVec RoutePath::pathForHold(Hold* hold) const
{
int turnSteps = 16;
double hdg = hold->inboundRadial();
double turnDelta = 180.0 / turnSteps;
double altFt = 0.0; // FIXME
double gsKts = d->perf.groundSpeedForAltitudeKnots(altFt);
SGGeodVec r;
double az2;
double stepTime = turnDelta / 3.0; // 3.0 is degrees/sec for standard rate turn
double stepDist = gsKts * SG_KT_TO_MPS * stepTime;
double legDist = hold->isDistance() ?
hold->timeOrDistance()
: gsKts * (hold->timeOrDistance() / 3600.0);
legDist *= SG_NM_TO_METER;
if (hold->isLeftHanded()) {
turnDelta = -turnDelta;
}
SGGeod pos = hold->position();
r.push_back(pos);
// turn+leg sides are a mirror
for (int j=0; j < 2; ++j) {
// turn
for (int i=0;i<turnSteps; ++i) {
hdg += turnDelta;
SGGeodesy::direct(pos, hdg, stepDist, pos, az2);
r.push_back(pos);
}
// leg
SGGeodesy::direct(pos, hdg, legDist, pos, az2);
r.push_back(pos);
} // of leg+turn duplication
return r;
}
double RoutePath::computeDistanceForIndex(int index) const
{
if ((index < 0) || (index >= static_cast<int>(d->waypoints.size()))) {
return 0.0;
}
auto it = d->waypoints.begin() + index;
if ((index == 0) || it->skipped) {
// first waypoint, distance is 0
return 0.0;
}
const auto ty = it->wpt->type();
if (ty == "via") {
return distanceForVia(static_cast<Via*>(it->wpt.get()), index);
}
if (ty == "discontinuity") {
return 0.0;
}
auto prevIt = d->previousValidWaypoint(index);
if (prevIt == d->waypoints.end()) {
return 0.0;
}
double dist = SGGeodesy::distanceM(prevIt->turnExitPos, it->turnEntryPos);
dist += prevIt->turnDistanceM();
if (!it->flyOver) {
// add entry distance
dist += it->turnDistanceM();
}
return dist;
}
double RoutePath::distanceForVia(Via* via, int index) const
{
auto prevIt = d->previousValidWaypoint(index);
if (prevIt == d->waypoints.end()) {
return 0.0;
}
WayptVec enrouteWaypoints = via->expandToWaypoints(prevIt->wpt);
double dist = 0.0;
SGGeod legStart = prevIt->wpt->position();
for (auto wp : enrouteWaypoints) {
dist += SGGeodesy::distanceM(legStart, wp->position());
legStart = wp->position();
}
return dist;
}
double RoutePath::trackForIndex(int index) const
{
const auto sz = static_cast<int>(d->waypoints.size());
if ((index < 0) || (index >= sz)) {
return 0.0;
}
if (d->waypoints[index].skipped)
return trackForIndex(index - 1);
const WayptData& wd(d->waypoints[index]);
if (!wd.legCourseValid)
return 0.0;
return wd.legCourseTrue;
}
double RoutePath::distanceForIndex(int index) const
{
const auto sz = static_cast<int>(d->waypoints.size());
if ((index < 0) || (index >= sz)) {
return 0.0;
}
return d->waypoints[index].pathDistanceM;
}
double RoutePath::distanceBetweenIndices(int from, int to) const
{
if (from < 0) {
from = 0;
}
const auto sz = static_cast<int>(d->waypoints.size());
if (to >= sz) {
to = sz - 1;
}
return d->distanceBetweenIndices(from, to);
}
SGGeod RoutePath::positionForDistanceFrom(int index, double distanceM) const
{
int sz = (int) d->waypoints.size();
if (index < 0) {
index = sz - 1; // map negative values to end of the route
}
if ((index < 0) || (index >= sz)) {
throw sg_range_exception("waypt index out of range",
"RoutePath::positionForDistanceFrom");
}
// find the actual leg we're within
if (distanceM < 0.0) {
// scan backwards
while ((index > 0) && (distanceM < 0.0)) {
// we are looking at index n, say 4, but with a negative distance.
// we want to look at index n-1 (so, 3), and see if this makes
// distance positive. We need to offset by distance from 3 -> 4,
// which is waypoint 4's path distance.
// note pathDistanceM is 0 for skipped waypoints, so this works out
distanceM += d->waypoints[index].pathDistanceM;
--index;
}
if (distanceM < 0.0) {
// still negative, return route start
return d->waypoints[0].pos;
}
} else {
// scan forwards
int nextIndex = index + 1;
while ((nextIndex < sz) && (d->waypoints[nextIndex].pathDistanceM < distanceM)) {
distanceM -= d->waypoints[nextIndex].pathDistanceM;
index = nextIndex++;
}
}
auto nextIt = d->nextValidWaypoint(index);
if (nextIt == d->waypoints.end()) {
// past route end, just return final position
return d->waypoints[sz - 1].pos;
}
// this is important so we start from a valid WP if we're
// working either side of a DISCON
auto curIt = d->previousValidWaypoint(nextIt);
if (curIt == d->waypoints.end()) {
SG_LOG(SG_NAVAID, SG_WARN, "Couldn't find valid preceeding waypoint " << index);
return nextIt->pos;
}
const WayptData& wpt = *curIt;
const WayptData& next = *nextIt;
if (next.wpt->type() == "via") {
return positionAlongVia(static_cast<Via*>(next.wpt.get()), index, distanceM);
}
if (wpt.turnPathDistanceM > distanceM) {
// on the exit path of current wpt
return wpt.pointAlongExitPath(distanceM);
} else {
distanceM -= wpt.turnPathDistanceM;
}
double corePathDistance = next.pathDistanceM - next.turnPathDistanceM;
if (next.hasEntry && (distanceM > corePathDistance)) {
// on the entry path of next waypoint
return next.pointAlongEntryPath(distanceM - corePathDistance);
}
// linear between turn exit and turn entry points
return SGGeodesy::direct(wpt.turnExitPos, next.legCourseTrue, distanceM);
}
SGGeod RoutePath::positionAlongVia(Via* via, int previousIndex, double distanceM) const
{
SG_LOG(SG_NAVAID, SG_ALERT, "RoutePath::positionAlongVia not implemented");
return SGGeod();
}