Multishading mask for a window with overhang

Adjust parameters:

S: Window's height
L: Overhang's length
T: Gap
Façade's azimuth:
Remarks:
The calculations will be performed only for the façade's area of interest (coloured in red on the section view).
All dimensions can be specified with any unit at any scale. Azimuth is defined clockwise from North: North=0° East=90° South=180° West=270°