Posted by Sven Gothel on Jun 01, 2023; 1:43pm
URL: https://forum.jogamp.org/Offscreen-buffering-and-antialiasing-not-working-tp4042649p4042665.html

   this.capabilities.setAlphaBits(8);
   this.capabilities.setOnscreen(false);
// this.capabilities.setSampleBuffers(true);
// this.capabilities.setNumSamples(4);

Then perhaps try

  this.capabilities.setAlphaBits(1); // <- the biggest will be used while having sample buffers >= 4
  this.capabilities.setOnscreen(false);
  this.capabilities.setSampleBuffers(true);
this.capabilities.setNumSamples(4);

In both cases, hmm .. try the debug option and pipe all into a file and attach,
I referenced a late post above ;-)

Then the following will also list all available formats/caps:

java -cp jogamp-fat.jar com.jogamp.newt.opengl.GLWindow

# with piped out file
java -cp jogamp-fat.jar com.jogamp.newt.opengl.GLWindow 2>&1 | tee test.log

The following will add debug code (also about chosen caps):

java -Djogl.debug=all -cp jogamp-fat.jar com.jogamp.newt.opengl.GLWindow

# with piped out file
java -Djogl.debug=all -cp jogamp-fat.jar com.jogamp.newt.opengl.GLWindow 2>&1 | tee test_dbg.log

.. hope that may help a little