This thread got busy [:)] Actually, the tricky thing - especially with non-rectangular rooms/corners - is to place the corners accurately to facilitate easier calculation later. The Advanced plan editing (found on the SF plugin page) is really useful (move room points, move all). That way the starting point can be set to 0.0 which makes everything easier.

BTW, if you want to play with non-rectangular shapes, sunlight simulation (see blog 14.11.2014) gives a good visualisation of light and shadow throughout the day.

Put example files in SF 3D models 372:

octagon_roof.sh3d
octagon_sun_sim.mp4
roof_oct.zip

ok