I am afraid it is not possible with the basic ArchiCAD tools.
The window and door objects can read the wall direction angle, but that angle
depends on the drawing direction; clockwise and anti-clockwise drawn walls are heading to opposite directions so it is just guessing if the direction is north or south.
Paodekcal wrote: How do I get the value of wall length that project on the North Elevation, or other direction?
You could either approximate this from the geometry expressed in the API_WallType structure, or more accurately from the 3D geometry accessed through the ModelAccess API.
