XPLMMapGetNorthHeading

XPLMMapGetNorthHeading

XPLM_API float      XPLMMapGetNorthHeading(
                         XPLMMapProjectionID  projection,
                         float                mapX,
                         float                mapY);

Returns the heading (in degrees clockwise) from the positive Y axis in the cartesian mapping coordinate system to true north at the point passed in. You can use it as a clockwise rotational offset to align icons and other 2-d drawing with true north on the map, compensating for rotations in the map due to projection.

Only valid from within a map layer callback (one of XPLMMapPrepareCacheCallback_f, XPLMMapDrawingCallback_f, XPLMMapIconDrawingCallback_f, or XPLMMapLabelDrawingCallback_f.)