glCopyPixels + GLX_SAMPLE_BUFFERS +glFinish + glDrawBuffer

[evena]

For an application that does it's own copying of the backbuffer to the frontbuffer using glCopyPixels, if multisampling is used, adding a call to gllFinish after glDrawBuffer causes glCopyPixels to fail.

Either the whole buffer is copied / drawing is sent to the front buffer, or no copying is done.

Tested drivers: 260.19.29 and 260.19.44

Compile with g++ -g -o bug main.C -lGL -lX11
run as:
./bug [ correct ]
./buf -f [ correct, including calls to glFinish() ]
./bug -ms [ correct multisampled ]
./bug -ms -f [ incorrect multisampled including calls to glFinish() ]

[danix]

Hello evena,

Could you please clarify how the expected correct behavior and the observed incorrect behavior is supposed to manifest? To be honest, all four runs of the app with the different combinations of multisampling and wether or not to call glFinish() look pretty similar to me, at least on the system that I tested.

[evena]

Hi danix,

The purpose is to update only a part of the frontbuffer,

If I use xv to grab the window,

bug-ok shows expected results
bug-ms-f1 shows result of running ./bug -ms -f1 (No update to front buffer)
bug-ms-f2 shows result of running ./bug -ms -f2 (Complete update to front buffer)

Regards,

Even

[danix]

Okay, thanks. In that case I was getting the correct result even in your failing case. I'll match your hardware/software configuration (from the nvidia-bug-report) more closely.

[evena]

Great,

Thank you for looking into this,


Even