Feel free to check out the code, but otherwise just watch and enjoy!
I've been trying to figure out for a while how to shade triangles using pen, especially with transparency in mind. After finding a tutorial, I created this! I may even use it with my 3D Rotatable Object project to add some color. In case you're wondering, here's the tutorial I used: http://www.sunshine2k.de/coding/java/TriangleRasterization/TriangleRasterization.html