Change emulator/shader resolution on high-res screen?

[Cannikin]

Pi Model: Zero W
RetroPie version: 4.6-rpi1_zero

I've got a 7" HDMI screen with a relatively high resolution, 1024x600. When I apply a shader like crt-pi-curvature.glslp it appears to be adding scan lines every other line, which is great, but at that resolution they're almost too fine to see and results in more of a moiré pattern.

Are there any tricks I can use to get this looking more like a proper CRT resolution? Can I tell the Pi to change the resolution of the screen, or tell RetroPie to display the emulators at a different resolution?

In this particular instance I'm only going to be running Atari 2600 games, if that matters. Although it's resolution is 40x192, it would still be displaying on a "CRT" with, what, 450-480 lines? 480/192 = 2.5...can libretro output 2.5 pixels for every 1 the emulator is sending out? Something like that?

Thanks for any help!

[Cannikin]

I found this walkthrough that does exactly what I want, but on Windows:

It depends on the CRTSwitchRes utility that lets you set a custom resolution on an external monitor. Once you do that (setting the vertical resolution to 480) you tell RetroArch to scale itself to that resolution and then the scanlines appear as expected.

How do I do that on a Pi Zero...hmmm

[mitu]

@Cannikin Does you display support multiple resolutions ? You can always switch the the video resolution via the runcommand launch menu, but if your display doesn't support it, then you're not be able to use this option. Have you tried other CRT shaders (zfast, phosphor) ?

[Cannikin]

@mitu said in Change emulator/shader resolution on high-res screen?:

@Cannikin Does you display support multiple resolutions ?

Not sure if it supports them natively...there was no documentation with the screen (it's this one: https://www.amazon.com/gp/product/B01F3801A2 )

However, during ROM startup I was able to use the Select Retroarch render res for lr-stella2014 option and set it down to 320x224 which got me a lot closer to something good! One strange thing is that I had to switch to the vertical shader?? You can see the scanlines now, but I have a super intense moiré happening:

I haven't tried any other shaders yet...I don't remember any others having such nice lines + bloom + curvature, but I'll give them a shot!

[Cannikin]

I set video_scale_integer = true and now have a different moiré pattern:

This is going to become a journey of just finding the least annoying ring pattern on the screen. 😅

[Cannikin]

Removing the curvature removes the morié pattern completely:

Which is a shame...I really love that curving for the old school feel, especially for the 2600 where there weren't any Trinitron sets yet!