Here is an update. There were some problems initially with file saving and loading. Everything should work fine this time. The program still outputs only transparent line art. The reason is it's easier to load into gimp or photoshop. Here is an example of the style of art it can be used for. Basically load the wireframe into your favorite paint package, color and paste some transparencies to create a stained glass effect. These can be used as textures for example in 3d scenes. Most paint packages can be setup to do this, but the program can be used quickly and conveniently to do the same thing. So it's like a plugin type application that can be extended to provide other options. Feel free to post any updates you might think can be useful to add.
I was cleaning out old source codes and found this old project, so I quickly created 3 new projects and updated it. I noticed there was an error with the last Linepaint app, so I fixed the border bug and added a border outline. Also, I quickly added a pixel editor and a threshold tool. The threshold tool is the same thresholding characteristic as is used by gimp. This is just a standard unit of measure, where you have 2 ranges instead of 1. So for example Adobe Photoshop's basic threhsold setting is for a single range. Gimp has a more versatile setup as a default in this way. I am attaching 3 projects, no binary files, I quickly slapped them together in visual studio community 2017. Please don't ask me questions about this. I'm not programming anymore and I just wanted to make sure, I leave behind some simple projects that were difficult for me when I was getting started. I hope you can make good use of them. Every once in a while if I find old sources and stuff I threw away, I will refresh them and try to drop them in the codebank.