/**
* Compute the lat/lon position of the view center
*
* @param dc the current DrawContext
* @param view the current View
* @return the ground position of the view center or null
*/
protected Position computeGroundPosition(DrawContext dc, View view) {
if (view == null) return null;
Position groundPos =
view.computePositionFromScreenPoint(
view.getViewport().getWidth() / 2, view.getViewport().getHeight() / 2);
if (groundPos == null) return null;
double elevation =
dc.getGlobe().getElevation(groundPos.getLatitude(), groundPos.getLongitude());
return new Position(
groundPos.getLatitude(),
groundPos.getLongitude(),
elevation * dc.getVerticalExaggeration());
}
/**
* Compute the view range footprint on the globe.
*
* @param dc the current <code>DrawContext</code>
* @param steps the number of steps.
* @return an array list of <code>LatLon</code> forming a closed shape.
*/
protected ArrayList<LatLon> computeViewFootPrint(DrawContext dc, int steps) {
ArrayList<LatLon> positions = new ArrayList<LatLon>();
Position eyePos = dc.getView().getEyePosition();
Angle distance =
Angle.fromRadians(
Math.asin(
dc.getView().getFarClipDistance()
/ (dc.getGlobe().getRadius() + eyePos.getElevation())));
if (distance.degrees > 10) {
double headStep = 360d / steps;
Angle heading = Angle.ZERO;
for (int i = 0; i <= steps; i++) {
LatLon p = LatLon.greatCircleEndPosition(eyePos, heading, distance);
positions.add(p);
heading = heading.addDegrees(headStep);
}
return positions;
} else return null;
}