I know from using OpenGL ES2 that it requires writing a custom shader. I don't know if Java has a default shader of some sort. The avoCADo-CAD project died while trying to convert from OpenGL 1 to 2, and I'm trying to finish the work.
I am using Eclipse.
I got one of the original developers on board for creating a new "official" repo (below) but he doesn't have time to write any code.
After modernizing use of AWT in all areas except OpenGL, I have trouble even getting the outline for the OpenGL2 calls correct (proper order of calls and proper argument) despite scouring documentation. There seem to be no working examples combining the various calls. Due to these factors, I cannot get it to build.
I have changed the name of the main project directory to librecsg and created a unique namespace to follow standards.
See the most recent commits at: https://github.com/avoCADo-3d/avoCADo/commits/master
See the screenshot for the main problem file and the error, but that may be the tip of the iceberg depending on how this goes.