You just need a drawing program that can handle .DDS files.
I use Paint.NET (free) and I would just load the appropriate window file (or drop and drag) into the program then I would delete the windows themselves then simply fill with a weak opacity of black then save as DTX5 (Interpolated Alpha) and see if that was okay.... it's all trial and error until you find the mix that suits you.
Does that help you??
Paint.Net. You will need to download the file from their forum that allows you to use DDS files but it's such a user friendly painting program to use.
Anzahl der Beiträge : 981 Anmeldedatum : 2016-02-23 Ort : In my other Shed