[Lazarus] TOpenGLControl: multisampling not working (Linux/GLX)

[Reimar Grabowski]

Hi,

as the title says multisampling does not work for me.
Setting the MultiSampling value to something greater than 1 does nothing.
Well, it does something. The multisampling code path in GLGtkGlxContext.pas is executed without any errors (verified by setting a break point and stepping through the code) but no multisampling enabled context is created as querying GL_SAMPLE_BUFFERS and GL_SAMPLES shows. Both are 0.
Forcing multisampling via driver settings GL_SAMPLE_BUFFERS is 1 (meaning multisampling is enabled on this context) and GL_SAMPLES is a non 0 value, too (depends on the driver settings, I tested with 4, 8 and 32 and all work correctly).
Does multisampling work under Linux/Gtk for anyone?

To test if it works you should query the mentioned enums like so:

var
samples, samplebuffers: integer;

glGetIntegerv(GL_SAMPLE_BUFFERS, @samplebuffers); // should be 1
glGetIntegerv(GL_SAMPLES, @samples); // should be the value of TOpenGLControl.MultiSampling


Thanks for any info
R.