Shaders can be set under retropie setup - Configedit (005), Configure basic libretto emulator options (0), configure default options for all libretto emulators
@Marinho Great thread, thanks for the info. I've been noticing the same thing here. Playing with shaders causes the system to run really hot. I thought it was just cause I was playing PSX games. But when the thermometer started showing up with SNES games I knew something was up.
Adding to what @MagiusRetro said, you could also have the settings he mentioned applied on a per-game basis to avoid having to deal with the drawbacks in all your other games. More information can be found at the link below.
If you're planning on using GLSL versions of those shaders on a Raspberry Pi I wouldn't get your hopes up. I had a quick look at a few of them and even the simplest look like they are doing too much processing for the Pi's GPU to handle at high frame rates.
@BuZz Thanks very much! I've been searching via Google for 2 days, and nothing. I guess they haven't updated with the forum content yet. I also searched the forums before I posted but must have missed this. Thanks again.
For anyone interested, I was able to figure this out,
I was using crt-pi shader, but for whatever reason this causes problems with genesis plus gx. Using crt-pi-vertical shader produces the identical results that I get in other emus using crt-pi shader.
@dankcushions I was able to get Galaga to work by disabling the video driver. Apparently it was using a proprietory driver. That said I cannot get the sound to work. I will do a separate post on that issue.