Amber CRT

A calm amber-phosphor CRT shader for Ghostty.

The look is inspired by cool-retro-term's amber scheme. It was fitted against cool-retro-term screenshots rather than eyeballed (see CALIBRATION.md).

Example

Before (a normal dark theme) and after (amber-crt applied):

mkdir -p ~/.config/ghostty/shaders
cp amber-crt.glsl ~/.config/ghostty/shaders/amber-crt.glsl

Then add to ~/.config/ghostty/config:

custom-shader = ~/.config/ghostty/shaders/amber-crt.glsl

Brightness comes almost entirely from luminance, so a light theme will just look like a solid orange rectangle. Pick something dark.

Everything is a #define at the top of the shader, with a comment explaining what it does. A few gotchas:

BLOOM_*, HALATION_* and SCANLINE_PERIOD are in device pixels, so on a differently scaled display, adjust those distances — not the colour stops.
Don't set SCANLINE_PERIOD to 2.0; the lines silently vanish.
On a weak GPU, set BLOOM_ENABLED 0 to skip the glow passes.

CC BY-NC-SA 4.0 — use and modify freely with attribution, but keep it non-commercial and share your changes under the same license.