VPL Diff

A static website to compare C64 palette files in VICE .vpl format, side by side.

• Server palettes live in palettes/ as .vpl files, listed in palettes/index.json (a JSON array of filenames).
• Your palettes are uploaded in the browser, parsed client-side, and stored in localStorage. Nothing is sent to any server.
• Palettes are shown as a table: one row per color index, one column per palette, so the same color slot always sits next to its counterpart in every other palette.
• Colors that differ from a chosen reference palette are outlined, and a footer counts how many colors differ per palette. (The dither nibble is ignored.)

There is no active server component — just HTML, client-side JS, CSS, and the .vpl files. You can also export any palette (server or uploaded) back to .vpl.

Adding server palettes

1. Drop a valid VICE .vpl file into palettes/.

2. Regenerate the manifest (requires jq):

   ./palettes/build-index.sh

   This rewrites palettes/index.json with every .vpl in the directory, sorted. (You can still edit index.json by hand instead.)

The VICE .vpl format

Plain text. # starts a comment; blank lines are ignored. Each colour line is whitespace-separated hexadecimal bytes:

# Red Green Blue Dither
00 00 00 0   # Black
ff ff ff f   # White

The parser reads the first three values as the RGB triplet and keeps the optional fourth (dither) nibble for round-tripping on export.

Deployment (GitHub Pages)

The repo ships a workflow at .github/workflows/deploy.yml that publishes the site to GitHub Pages on every push to main/master.

One-time setup: in the repository, go to Settings → Pages → Build and deployment and set Source to GitHub Actions. After the next push the site is served at https://<user>.github.io/<repo>/. All asset paths are relative, so it works under that project subpath unchanged.

License

MIT © Dirk Heilig