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Expose position along the flight-path to Nasal.

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Useful to query a point '100nm before wpt X' from Nasal, especially for VNAV calculations (T/C, T/D).
This commit is contained in:
James Turner 2012-12-26 23:48:19 +00:00
parent a1031b052d
commit 12076bce0e
3 changed files with 67 additions and 1 deletions
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33
src/Navaids/FlightPlan.cxx
View file

@ -1035,6 +1035,39 @@ void FlightPlan::rebuildLegData()
}
}
SGGeod FlightPlan::pointAlongRoute(int aIndex, double aOffsetNm) const
{
if (aIndex >= (int) _legs.size()) {
throw sg_range_exception();
}
const int lastLeg = static_cast<int>(_legs.size()) - 1;
// convert the relative offset and leg index into an absolute, positive
// distance in nm from the route origin. This means we can simply walk
// forwards to find the actual leg.
Leg* leg = _legs[(aIndex >= 0) ? aIndex : lastLeg];
double absolutePathDistance = leg->_distanceAlongPath + aOffsetNm;
if (absolutePathDistance < 0.0) {
return _legs[0]->waypoint()->position(); // begining of route
}
if (absolutePathDistance > _totalDistance) {
return _legs[lastLeg]->waypoint()->position(); // end of route
}
// find the leg containing the absolute distance
for (int l=0; l<lastLeg; ++l) {
leg = _legs[l];
if (absolutePathDistance < leg->_pathDistance) {
break; // found our matching leg
}
absolutePathDistance -= leg->_pathDistance;
} // of forwards walk along route to find leg
return SGGeodesy::direct(leg->waypoint()->position(),
leg->_courseDeg, absolutePathDistance * SG_NM_TO_METER);
}
void FlightPlan::lockDelegate()
{
if (_delegateLock == 0) {

7
src/Navaids/FlightPlan.hxx
View file

@ -199,6 +199,13 @@ public:
double totalDistanceNm() const
{ return _totalDistance; }
/**
* given a waypoint index, and an offset in NM, find the geodetic
* position on the route path. I.e the point 10nm before or after
* a particular waypoint.
*/
SGGeod pointAlongRoute(int aIndex, double aOffsetNm) const;
/**
* Create a WayPoint from a string in the following format:
* - simple identifier

28
src/Scripting/NasalPositioned.cxx
View file

@ -2125,6 +2125,31 @@ static naRef f_flightplan_clone(naContext c, naRef me, int argc, naRef* args)
return ghostForFlightPlan(c, fp->clone());
}
static naRef f_flightplan_pathGeod(naContext c, naRef me, int argc, naRef* args)
{
FlightPlan* fp = flightplanGhost(me);
if (!fp) {
naRuntimeError(c, "flightplan.clone called on non-flightplan object");
}
if ((argc < 1) || !naIsNum(args[0])) {
naRuntimeError(c, "bad argument to flightplan.pathGeod");
}
if ((argc > 1) && !naIsNum(args[1])) {
naRuntimeError(c, "bad argument to flightplan.pathGeod");
}
int index = (int) args[0].num;
double offset = (argc > 1) ? args[1].num : 0.0;
naRef result = naNewHash(c);
SGGeod g = fp->pointAlongRoute(index, offset);
hashset(c, result, "lat", naNum(g.getLatitudeDeg()));
hashset(c, result, "lon", naNum(g.getLongitudeDeg()));
return result;
}
static naRef f_leg_setSpeed(naContext c, naRef me, int argc, naRef* args)
{
FlightPlan::Leg* leg = fpLegGhost(me);
@ -2365,7 +2390,8 @@ naRef initNasalPositioned(naRef globals, naContext c, naRef gcSave)
hashset(c, flightplanPrototype, "cleanPlan", naNewFunc(c, naNewCCode(c, f_flightplan_clearPlan)));
hashset(c, flightplanPrototype, "clearWPType", naNewFunc(c, naNewCCode(c, f_flightplan_clearWPType)));
hashset(c, flightplanPrototype, "clone", naNewFunc(c, naNewCCode(c, f_flightplan_clone)));
hashset(c, flightplanPrototype, "pathGeod", naNewFunc(c, naNewCCode(c, f_flightplan_pathGeod)));
waypointPrototype = naNewHash(c);
hashset(c, gcSave, "wayptProto", waypointPrototype);