Raspberry Pi Forums

rpi video output in mpv player uses mmal video output and OpenGL ES for osd.
But the legacy opengl es code does not work in RPi 4 . SO I want to replace the dispmanX specific code.

There is an example, kmscube which I can not use, because

• It requires root, and I dont want to give a media player root access.
  It does not work for me.

Is there any working example of opengl es code using GBM/DRM ?
Is it possible to do without root ?

Did you check this thread?
https://www.raspberrypi.org/forums/view ... 7#p1499181

The example code there runs without root.

Yes, I already checked that thread.
But that also does not work.
Running without root gives the following errors... Running with root does not show error. But also does not display anything.
Not even a black screen. Program starts , waits for a sec and the exits

A quick compile and run, and the example works fine.

At a guess you are running from within X. Trying to run it from X does indeed give me the errors you report.
Note the title comment on the example

Trying to get OpenGL ES screen on RPi4 without X

DRM supports a single client at a time. If X is running then it is the one true client, and anything else will be told permission denied. This is expected.
If you wish to run within X then you need to look at composing via EGL, not via GBM/DRM.

Yes. You are right. I am using X.
Thanks.