Cauldron2D.Easel

This package edits cauldron_2d art as data. A picture is a palette and frames of palette keys. The easel also holds the frame in hand and a history to undo through. Every operation on it is a pure function. The terminal, browser and Livebook editors are built on it, and a game or a script can call it directly to make or change art.

Installation

Add the dependency to mix.exs:

def deps do
  [
    {:cauldron_2d_easel, "~> 0.3"}
  ]
end

Usage

Make a picture, paint it, and save it:

easel = Cauldron2D.Easel.new(16, 16, palette: [{"R", "#c33"}, {"W", :white}])
easel = easel |> Cauldron2D.Easel.paint({3, 4}, "R") |> Cauldron2D.Easel.fill({0, 0}, "W")
easel = Cauldron2D.Easel.undo(easel)
:ok = Cauldron2D.Easel.save(easel, "priv/art/ship.pic")

Open an art directory, change an art, and install the directory as an atlas:

project = Cauldron2D.Easel.Project.open("priv/art", tile: 16)
Cauldron2D.Easel.Project.arts(project)
{:ok, easel} = Cauldron2D.Easel.Project.load(project, :ship)
{:ok, project} = Cauldron2D.Easel.Project.save(project, :ship, easel)
{:ok, :my_game} = Cauldron2D.Easel.Project.install(project, :my_game)

install/2 builds the atlas with Cauldron2D.Atlas.load/3 and installs it. A game in the same VM can subscribe to the atlas with Cauldron2D.Atlas.subscribe/1. It then draws the new art on its next frame.

Module	What it does
`Cauldron2D.Easel`	Holds one picture being edited. It paints, draws lines and rectangles, fills and erases. It flips, rotates and shifts frames. It adds, sets, renames and removes palette colours. It adds, duplicates, deletes, moves and selects frames, and sets their rate. It undoes and redoes. `derive/3` makes a new picture from a `Linocut.Derive` line. It reads and writes `.pic` and `.png`.
`Cauldron2D.Easel.Project`	Works on an art directory. It lists the arts, and loads, saves, creates and clones them. It derives an art from another by a line in the manifest, `atlas.txt`. The manifest also holds each art's glyph, colour and rate. `install/2` installs the directory as an atlas.
`Cauldron2D.Easel.View`	Turns an easel into what a browser canvas draws. That is the frame in hand as CSS colours, the onion-skin frame, the palette, and the frame count and rate. The LiveView and Livebook editors send it to their scripts.
`Cauldron2D.Easel.Sectors`	Holds a sector map being edited. You draw rooms as polygons on a grid. Rooms that share an edge are joined. Each room and wall has its own heights, pictures and light. Edits can be undone. `to_map/2` gives the `Cauldron2D.Sectors` map a game plays.
`Cauldron2D.Easel.SectorArt`	Gives pictures for previewing a sector map that has no game art yet. The palette is sixteen hues in sixteen shades. The wall, floor and ceiling textures are drawn from it. They come as a `Cauldron2D.Sectors.Pictures` set.

The document is what a .pic file holds (Linocut.Pic). It is palette lines, a blank line, and then the frames separated by ---. An edit changes a key in a grid. A recolouring changes one palette line. A key is one character, and . is transparent. A .png holds the frames side by side. Reading one gives every distinct colour its own key. There are ninety keys, so a .png with more colours is refused.

How it fits

Each editor is its own package that holds an easel and draws it:

cauldron_2d_easel_drafter runs in the terminal and also has the sector editor.
cauldron_2d_easel_web runs in a browser with LiveView.
cauldron_2d_easel_kino runs in Livebook.

The editors install the Cauldron2D.Atlas a game draws from. The terminal renderer in cauldron_2d_drafter draws the atlas directly. cauldron_2d_net makes a sprite sheet from it. The browser and the window in cauldron_2d_wx draw that sheet.

License

MIT