crt + vhs (CanvasItem)

test shader for godot (im learning shaders so feedback is welcome)

A full-screen retro post-process shader for Godot 4.5 / 4.6 that adds:

- CRT curvature + vignette + rounded corners

- Scanlines + optional RGB triad “shadow mask”

- VHS/VCR artifacts (chroma shift, horizontal smear, per-line jitter, tracking lines, roll bar)

- Cheap glow on bright pixels

- Simple color grading (brightness/contrast/saturation/gamma)

## How to use

1. Create a `CanvasLayer`

2. Add a `ColorRect` as a child

3. Set `ColorRect` → **Layout → Full Rect**

4. Create a `ShaderMaterial` on the `ColorRect`

5. Paste the shader into a new `Shader` resource

6. (Optional) Set `ColorRect` → **Mouse → Filter = Ignore** (so it won’t block UI input)

### UI layering tip

If you want your UI unaffected, put UI on a higher `CanvasLayer` than the effect.

This shader uses `hint_screen_texture` + `SCREEN_UV`, so it processes whatever has already been drawn behind it.

## Key parameters to tweak

- CRT glass: `curvature`, `vignette`, `corner_soften`

- Scanlines/phosphor: `scanline_strength`, `scanline_density`, `mask_strength`, `mask_scale`

- VHS noise: `jitter_px`, `tape_noise`, `tape_lines`, `roll_speed`, `roll_strength`

- Color grade: `brightness`, `contrast`, `saturation`, `gamma`

- Bloom-ish: `glow_strength`, `glow_threshold`