wt-crt-effect

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A HLSL pixel shader that make Windows Terminal look like a CRT (cathode-ray tube) monitor.

Windows Terminal can load .hlsl pixel shaders per profile via the experimental.pixelShaderPath setting. This repository provides retro-style shaders built on that mechanism.

Requirements

• Windows Terminal 1.6 or later (versions that support experimental.pixelShaderPath)
• A GPU capable of running pixel shaders (any recent Windows PC is normally fine)

Installation

Option A: Bundled script (recommended)

Running the following in PowerShell automatically sets experimental.pixelShaderPath on the default profile in your settings.json (a backup is created beforehand).

# Apply the shader
./install.ps1

# Revert
./install.ps1 -Uninstall

Option B: Manual

1. Open Windows Terminal, press Ctrl+, for Settings → "Open JSON file" at the bottom left.

2. Add experimental.pixelShaderPath under profiles.defaults to apply it to all profiles at once — Windows PowerShell, Command Prompt, PowerShell (pwsh), WSL, etc. (adjust the path to your environment; escape \ as \\).

   {
       "profiles": {
           "defaults": {
               "experimental.pixelShaderPath": "C:\\path\\to\\wt-crt-effect\\shaders\\crt.hlsl"
           }
       }
   }

   To apply it to a single profile only, put the same line inside that profile in profiles.list instead. A per-profile setting overrides defaults.

3. It takes effect immediately upon saving.

See settings-example.json for a minimal sample.

Customization

You can change the effect by editing the tunable parameters at the top of shaders/crt.hlsl. Windows Terminal reloads automatically when you save.

Parameter	Description	Default
FISHEYE_STRENGTH	Fisheye bulge. 0 = flat, around 0.5 = strong sphere	0.06
ZOOM	Shrink to compensate for edge clipping (0.85–1.0). Higher = narrower bezel	1.00
SCANLINE_STRENGTH	Scanline intensity (higher = more pronounced)	0.80
SCANLINE_DENSITY	Scanline density (smaller = thicker, more visible lines)	1.0
SCANLINE_DRIFT	Time-varying scanline frequency; makes the moiré rings drift/breathe. 0 = static	0.02
SCANLINE_DRIFT_SPEED	Speed of the breathing wobble. Lower = slower	0.04
SATURATION	Saturation. 1 = unchanged, >1 = more vivid	1.65
MASK_STRENGTH	Strength of the RGB vertical-stripe mask (0..1)	0.28
BLUR_AMOUNT	Soft focus on the text. 0 = sharp, 1 = fully blurred	0.50
BLUR_RADIUS	Blur kernel radius, in pixels	1.1
CHROMA_OFFSET	Chromatic aberration (RGB shift)	0.0018
VIGNETTE_POWER	Vignette strength	0.22
VIGNETTE_MIN	Brightness floor at the edges (higher = brighter, more readable)	0.70
FLICKER_AMOUNT	Brightness flicker	0.03
GRAIN_AMOUNT	Film noise amount	0.06
BLOOM_AMOUNT	Phosphor glow (bleed)	0.45
BRIGHTNESS	Overall brightness compensation	1.32
SCREEN_GRAY	Screen black level. 0 = pure black background, higher = grayer	0.05

To weaken the fisheye, lower FISHEYE_STRENGTH (e.g. 0.15); set it to 0 to make the screen flat.

Appendix: Recommended combination

The author likes pairing this with the pure theme of oh-my-posh. A simple prompt goes well with the CRT effect and brings out the retro terminal atmosphere.

Add the following to your PowerShell profile ($PROFILE):

oh-my-posh init pwsh --config 'pure' | Invoke-Expression

If oh-my-posh is not installed, you can get it via winget install JanDeDobbeleer.OhMyPosh or similar. See the oh-my-posh documentation for details.

License

MIT