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Work on an azimuthal project mode for the map, to improve behaviour in polar regions. Disabled for now since performance is extremely poor.

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This commit is contained in:
James Turner 2012-04-21 11:14:45 +01:00
parent 2a4ab38e70
commit 2e5febec7d
2 changed files with 40 additions and 10 deletions
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49
src/GUI/MapWidget.cxx
View file

@ -387,7 +387,8 @@ MapWidget::MapWidget(int x, int y, int maxX, int maxY) :
_width = maxX - x;
_height = maxY - y;
_hasPanned = false;
_orthoAzimuthProject = false;
MapData::setFont(legendFont);
MapData::setPalette(colour);
@ -1446,13 +1447,30 @@ void MapWidget::drawAIShip(const SGPropertyNode* model, const SGGeod& pos, doubl
SGVec2d MapWidget::project(const SGGeod& geod) const
{
// Sanson-Flamsteed projection, relative to the projection center
SGVec2d p;
double r = earth_radius_lat(geod.getLatitudeRad());
double lonDiff = geod.getLongitudeRad() - _projectionCenter.getLongitudeRad(),
latDiff = geod.getLatitudeRad() - _projectionCenter.getLatitudeRad();
SGVec2d p = SGVec2d(cos(geod.getLatitudeRad()) * lonDiff, latDiff) * r * currentScale();
if (_orthoAzimuthProject) {
// http://mathworld.wolfram.com/OrthographicProjection.html
double cosTheta = cos(geod.getLatitudeRad());
double sinDLambda = sin(geod.getLongitudeRad() - _projectionCenter.getLongitudeRad());
double cosDLambda = cos(geod.getLongitudeRad() - _projectionCenter.getLongitudeRad());
double sinTheta1 = sin(_projectionCenter.getLatitudeRad());
double sinTheta = sin(geod.getLatitudeRad());
double cosTheta1 = cos(_projectionCenter.getLatitudeRad());
p = SGVec2d(cosTheta * sinDLambda,
(cosTheta1 * sinTheta) - (sinTheta1 * cosTheta * cosDLambda)) * r * currentScale();
} else {
// Sanson-Flamsteed projection, relative to the projection center
double lonDiff = geod.getLongitudeRad() - _projectionCenter.getLongitudeRad(),
latDiff = geod.getLatitudeRad() - _projectionCenter.getLatitudeRad();
p = SGVec2d(cos(geod.getLatitudeRad()) * lonDiff, latDiff) * r * currentScale();
}
// rotate as necessary
double cost = cos(_upHeading * SG_DEGREES_TO_RADIANS),
sint = sin(_upHeading * SG_DEGREES_TO_RADIANS);
@ -1472,10 +1490,21 @@ SGGeod MapWidget::unproject(const SGVec2d& p) const
double r = earth_radius_lat(_projectionCenter.getLatitudeRad());
SGVec2d unscaled = ur * (1.0 / (currentScale() * r));
double lat = unscaled.y() + _projectionCenter.getLatitudeRad();
double lon = (unscaled.x() / cos(lat)) + _projectionCenter.getLongitudeRad();
return SGGeod::fromRad(lon, lat);
if (_orthoAzimuthProject) {
double phi = length(p);
double c = asin(phi);
double sinTheta1 = sin(_projectionCenter.getLatitudeRad());
double cosTheta1 = cos(_projectionCenter.getLatitudeRad());
double lat = asin(cos(c) * sinTheta1 + ((unscaled.y() * sin(c) * cosTheta1) / phi));
double lon = _projectionCenter.getLongitudeRad() +
atan((unscaled.x()* sin(c)) / (phi * cosTheta1 * cos(c) - unscaled.y() * sinTheta1 * sin(c)));
return SGGeod::fromRad(lon, lat);
} else {
double lat = unscaled.y() + _projectionCenter.getLatitudeRad();
double lon = (unscaled.x() / cos(lat)) + _projectionCenter.getLongitudeRad();
return SGGeod::fromRad(lon, lat);
}
}
double MapWidget::currentScale() const

1
src/GUI/MapWidget.hxx
View file

@ -94,6 +94,7 @@ private:
bool _hasPanned;
SGGeod _projectionCenter;
bool _orthoAzimuthProject;
SGGeod _aircraft;
SGGeod _clickGeod;
SGVec2d _hitLocation;