Oh and one more..
I found something called 'ImageMajik' if i use those kind of external tool ,Can others use my .rb file without
installing 'ImageMajik' in sketchup just by applying .rb to plugin folder ?

if they don't need to install , let me know how to install those please.

what i meant was i need to cut those colored windows so that i can use it, not in the rectangle in the windows.

thanks

No,I meant i need to use that specific colored window so i have to draw lines to use each of these window. i didnt meant to use those rectangle inside windows.
thank you for ur comment.

My material has bunch of 'windows' on it and between each of it, there is an alpha space ( which is empty, so u can see through it).
I usually put my material on the temporary face and draw lines following the windows so that i can use the specific window I want to use.
so I want to program draws line following the windows ( which really has image) on the face and throw the empty space and the edges of the temporary face only.

not sure i deliver my intend well...

but the problem is I can't figure out where the empty space is.
so can you recommend me how to read the alpha space from my materials ?

example of my materials