Posted by Martin on Aug 05, 2022; 4:27pm
URL: https://forum.jogamp.org/Swing-panel-displays-pixels-of-previous-frame-where-pixels-of-current-frame-have-alpha-1-tp4041804p4041809.html

Hi,

Thank you Jeff for sharing your experience on this. I can add something a bit similar : usually, when keeping the same 3D viewpoint in a GLJPanel, the content is a bit darker at the first frame. I then get the correct coloring after 2 or 3 frames.

GLJPanel also uses the idea of processing GL offscreen (see the backend initialization here) .

The offscreen backend relies on an OpenGL PBuffer allowing to retrieve a BufferedImage. I sometime see an FBOUtil so I am not sure the backend always use a PBuffer, but in both case this is the same idea of rendering offscreen.

I don't think you loose anything with your DrawableUtils compared to GLJPanel. And you have a more readable code :) The source code of GLJPanel is big (2600+ LOC!) so it will be hard to debug. I'll probably follow your approach if I can't find an explanation for this bug.