Posted by gouessej on Feb 05, 2020; 3:32pm
URL: https://forum.jogamp.org/Frame-with-transparent-background-tp4040332p4040333.html

Hello

The OpenGL pipeline of Java2D in Java >= 8 doesn't rely on JOGL, it uses its own native pipeline with JNI, you can look at the source code of the classes in the package "sun.java2d.opengl" to confirm.

P.S: Maybe this helps:
https://docs.oracle.com/javase/tutorial/uiswing/misc/trans_shaped_windows.html