Installing Retropie on Raspian RPI3 B+

[Whyme193]

I have a Raspberry Pi 3 B+ running the latest raspian stretch and I am trying to set my RPi up to where i can boot it up to raspian and then preferably launch emulationstation and play my games I have followed the instructions here: https://retropie.org.uk/docs/Manual-Installation/ for installing on raspian, and set the auto-start to launch in terminal. i type "emulationstation" in the terminal and get

lvl0: 	Error creating SDL window!
	Could not get EGL display
lvl0: 	Renderer failed to initialize!
lvl0: 	Window failed to initialize!

am I missing something?
any help would be gratefully appreciated

[mitu]

@Whyme193 You need to exit the desktop environment, to the command line, and run the command. Emulationstation and almost all RetroPie emulators will not work from the X.org desktop environment.
Also, if you're using the new OpenGL driver, this is not compatible with RetroPie.

[Efriim]

Will the new OpenGL drivers ever be compatible, is it up to emulationstation devs? or will the emulators not work too? Does Pegasus-FE work with Opengl?

On my pi in the /boot/config.txt I have this hashed out in order to use the default driver.
#dtoverlay=vc4-fkms-v3d <--new opengl driver with full KMS (kernelmode switching)
One can change it using sudo raspi-config >> 7 advanced options >> A7 GL Driver

You will also want to add a higher gpu_mem split. >> A3 Memory Split > 256 should be good.

[mitu]

@Efriim said in Installing Retropie on Raspian RPI3 B+:

Will the new OpenGL drivers ever be compatible, is it up to emulationstation devs? or will the emulators not work too? Does Pegasus-FE work with Opengl?

Most of the emulators (and Emulationstation) are using the - native - OpenGL ES stack available on RPI, which doesn't need an X.org and has direct hardware acceleration. IMHO there's little advantage in using OpenGL instead of the native stack, but I haven't run any benchmarks.
The downside of using the - new - OpenGL driver is that certain utilities that rely on the native driver (tvservice for instance) might not work and functionality that's right now included in RetroPie would not be available.
You can find the original discussion here.