Cauldron2D.DrawList (Cauldron2D v0.2.2)

A frame as a list of pictures placed in pixels, and the raster it draws.

An item is a map:

:picture — any term naming a picture; render/4 looks it up
:position — {x, y} in world pixels, where the picture's origin lands
:depth — greater depth is drawn first, further back; items of equal depth draw in list order. Default 0
:origin, :scale, :angle, :blend, :alpha, :mode — as Cauldron2D.Blend.draw/6 takes them

Items hold only terms, so a draw list can be sent to another machine and drawn there from that machine's own pictures.

items = [
  %{picture: {:sprite, 4, 0}, position: {120, 88}, origin: {9, 28}, depth: 0},
  %{picture: {:tile, 2, 17}, position: {96, 96}, depth: 100}
]

raster = Cauldron2D.DrawList.render(items, {320, 200}, &MyGame.picture/1,
  view: {40, 0}, background: {20, 20, 40, 255})

A :picture scene returns that raster from its function of the pane's size.

Summary

Functions

extent(item, arg)

{left, top, right, bottom}, a rectangle in item's pixels that holds every pixel its picture, size {width, height}, can cover, whatever its scale and angle.

in_depth_order(items)

items in the order they are drawn: greatest depth first, ties in list order.

render(items, size, pictures, opts \\ [])

The raster of items, size {width, height} pixels, each item's picture found by pictures, a function from the item's :picture to a FrenchCurve.Raster or nil (an item whose picture is nil is skipped).

Types

item()

@type item() :: %{
  :picture => term(),
  :position => {number(), number()},
  optional(:depth) => number(),
  optional(:origin) => {number(), number()},
  optional(:scale) => {number(), number()},
  optional(:angle) => number(),
  optional(:blend) => {byte(), byte(), byte()},
  optional(:alpha) => number(),
  optional(:mode) =>
    :over | :add | :subtract | {:gamemaker, :over | :add | :subtract}
}