Gradient

Gradient is a small Amiga Commodity I wrote for my Amiga 600. It drives one or more Workbench color registers from a user copperlist, painting smooth dithered vertical gradients across the desktop.

It runs as a background broker registered with Commodities Exchange (so you can show / hide / disable / remove it through the standard Exchange app), keeps its settings in ENVARC:Gradient.prefs, and is fully WHDLoad-safe - the gradient temporarily disappears while a game has the chipset, and returns automatically when the game exits.

Source & download

Source code, build instructions, and end-user install / usage docs:
https://github.com/arttu76/gradient

The repository contains the C source (gradient.c), a Makefile that cross-compiles to AmigaOS Hunk format using vbcc, and documentation: README.md for installing and using the binary on the Amiga side, BUILDING.md for setting up the cross-toolchain on Linux.

Features

• Drives any of the 4 Workbench color registers via copperlist; each register independently enabled, dithered (ordered vertical Bayer), or reversed.
• Up to 8 gradient stops per register, edited via a GadTools window with R / G / B / Y sliders that update the live copperlist as you drag.
• Standard Amiga prefs convention: Save (write ENVARC: + ENV:), Use (write ENV: only), Cancel (revert).
• Commodities Exchange integration: Show / Hide pop the editor window; Enable / Disable attach / detach the copperlist; Remove quits.
• Launching Gradient while it's already running pops the editor window (Commodities NBU_UNIQUE) - never two instances fighting over the copperlist.
• Project menu, About... dialog, working $VER: cookie for AmigaDOS Version.
• Task priority dropped to -1 at startup - the copper does all the work, the program just sleeps on signals.
• Tooltype-aware Workbench launch: BACKGROUND skips the editor window at boot, LOAD=path loads a custom preset.

Target hardware

Built and tested on Amiga 600 with Kickstart / Workbench 3.1 (ECS, 68000). Should work on any OS 3.x Amiga - it uses only V37+ APIs and 68000-only instructions.

Install & configure

Short version: copy Gradient into SYS:Tools/Commodities/, copy a Blanker icon as a template, double-click on Workbench, edit, click Save. To autostart at boot, put a copy in SYS:WBStartup/ with DONOTWAIT and BACKGROUND tooltypes.

Full step-by-step instructions are in the README: README on GitHub.