I just made a small math curve drawing shader because i hardly needed the same thing i use in unity3D…
I share the blend 
here’s the topic: Math function drawer inside blender
Now back to my stained glass 
@silex: I won’t draw the windstoppers ( that i thought were grids preventing children from throwing stones over the windows 
) as they are visually annoying and heavier to draw in real time.
But i definetely will dirt the glass
Happy blending !