X-less Graphics on DPI and HDMI - Pi3B+

[allpass]

I've been messing around for a few days trying to figure out the best way to drive both a DPI and HDMI screen at the same time without X. My test setup has a small TFT connected to the DPI pins, and an HDMI monitor. My test software is: omxplayer, kmscube, and SDL2 2.0.10 with a custom test program. My eventual application will hopefully use GL rendering running on both DPI and HDMI displays at the same time.

It appears that the fake KMS driver is the only one that permits both omxplayer (which uses vc_dispmanx_ backend) and the KMS programs to work properly. However I was unable to run two GL programs at the same time, or select which display a GL program outputs on.

So some questions:

• Can two GL programs be run at the same time?
• How can a program using the KMS API (like kmscube) be told to display on a specific screen? (DPI vs. HDMI)
• Why does the "full" KMS driver not work with programs that use vc_dispmanx_ like omxplayer?
• Has anyone had success using SDL2 with the "RPI" videodriver? I compiled it but can't figure out the right combination of EGL and GL drivers to use.

Thanks in advance for any help!

[HermannSW]

Hi, 6by9 helped me answering similar question I had two weeks ago -- you can select the display to output on for raspivid with "-dn ...". You can find the number to pass in 6by9's checkin comment:
https://www.raspberrypi.org/forums/view ... 4#p1545341

[allpass]

Hi Hermann,

Thanks for the reply... but I'm not sure this is what I need. I don't know what raspivid is, and I have already successfully targetted multiple screens with omxplayer which uses the dispmanx stuff and not the GL stuff.