Shaders

RetroArch ships with hundreds of shaders that recreate CRT scanlines, LCD grids, NTSC artifacts, etc. ArchR enables them but defaults to off — A35 + Mali-G31 is tight, and naive multi-pass shaders will halve your framerate.

Try a built-in shader

Launch a game

Any libretro core. Standalones (PPSSPP, Flycast, etc.) have their own shader systems; this guide is for libretro/RetroArch.

MODE + X → Quick Menu → Shaders.

Set Video Shaders to ON

Then Load Preset → browse shaders_glsl/.

Pick a preset

Recommended starting points for the R36S 480p panel:

File path	Use case
`shaders_glsl/handheld/lcd1x.glslp`	LCD grid for GB / GBA / NDS
`shaders_glsl/handheld/lcd3x.glslp`	Sharper LCD grid
`shaders_glsl/crt/crt-pi.glslp`	Light CRT for arcade
`shaders_glsl/scanline/scanline.glslp`	Just scanlines, ultra-cheap

The preset applies immediately. Back out of the menu to play.

Save the preset for the system

In the Shaders menu, Save → Save Game Preset (just this game) or Save Core Preset (every game on this core) or Save Content Directory Preset (all games in this folder).

Per-game presets land in /storage/.config/retroarch/config/<core>/<game>.glslp. Per-core in /storage/.config/retroarch/config/<core>/<core>.glslp.

Build a custom multi-pass preset

The example below is the canonical "GBA real hardware" look — color-correct + LCD grid in two passes:

Open Shaders, change passes to 2

Quick Menu → Shaders → Shader Passes → 2.

Pass 1 — color correction

Click pass 1 → browse to shaders_glsl/handheld/ → choose vba-color.glslp.

Pass 2 — LCD grid

Click pass 2 → browse to shaders_glsl/handheld/ → choose lcd1x.glslp.

Apply

Hit Apply Changes.

Tune parameters

Shader Parameters is where each shader exposes its knobs. For this combo:

Darken: 0.25
Brighten Scanlines: 28.0
Brighten LCD: 6.0

Save

Back at the Shaders menu → Save → set Simple Presets to off → Save Shader Preset As → name it (e.g. gba-real-hw).

The named preset shows up under Load Preset the next time, and is also selectable from ES → Game Settings → Per System Advanced Configuration → Shader Set.

Performance budget

The R36S has very little overhead for shader passes. As a rule of thumb on RK3326 with overclock OFF (1.4 GHz CPU + 650 MHz GPU):

Tier	Ok?	Examples
1 cheap pass	✅	scanline, lcd1x, vba-color
1 expensive pass	usually ✅	crt-pi, crt-easymode
2 cheap passes	usually ✅	gba-real-hw (vba-color + lcd1x)
2 expensive passes	⚠️	crt-royale, crt-aperture-grille
3+ passes	❌	most CRT-Royale variants

Dreamcast / N64 / PSP cores already eat the GPU; even a 1-pass shader on top can drop you below 60 fps. Reserve fancy shaders for 8 / 16-bit cores.

Toggle Enable CPU Overclock if you want to try heavier shaders — see Overclock.

ES exposes a shader-set picker without going into RetroArch:

ES → Game Settings → Per System Advanced Configuration → Shader Set → pick from the dropdown.

This applies the chosen shader to every game on that system. Useful as a quick toggle. Custom presets you saved earlier appear here too.