Cauldron2D.Projection.Mode7 (Cauldron2D v0.2.2)

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Composes the world as a ground plane seen in perspective from above it, turning freely: the floor recedes to a horizon, movers stand on it as billboards, and everything fades towards the atlas's void colour with distance.

Cauldron2D.Projection.Mode7.render(:my_game,
  position: {12.5, 8.5},
  heading: :math.pi() / 2,
  cell: &MyGame.cell/1,
  size: {320, 200},
  movers: [{:hero, {14.5, 8.5}, 0.0}]
)

The plane is drawn from each cell's :top face, so a cell with storeys lies flat like any other: this projection has no verticality. Use Cauldron2D.Projection.Iso, Cauldron2D.Projection.Oblique or Cauldron2D.Projection.FirstPerson for a world whose walls must stand up.

Unlike the isometric view the heading is continuous, so a game may turn by any angle.

Options

  • :position — {x, y} in tiles, where the camera is, required
  • :heading — radians, 0 along +x, required
  • :cell — fn {x, y} -> cell end, as Cauldron2D.Surface takes cells; :void is drawn as the void colour, required
  • :size — {width, height} of the picture in pixels, required
  • :eye — how far above the plane the camera sits, in tiles. Default 1.6
  • :pitch — -0.8..0.8, how far the horizon is moved down or up the picture. Default 0.0
  • :aspect — a pixel's width over its height, so a picture drawn into cells that are not square keeps its proportions. Default 1.0
  • :fov — the horizontal field of view in degrees. Default 70
  • :range — how many tiles away the plane fades out entirely. Default 24
  • :sky — {top, bottom} colours above the horizon. Default a blue gradient
  • :movers — [{art, {x, y}}] or [{art, {x, y}, heading}]; a mover shows its :front pose when heading towards the camera, :back away, :side across (mirrored one way); with no heading it faces the camera. Default []
  • :volumes — coloured regions of space, as Cauldron2D.Projection.Volume describes them, each tinting the plane and the movers behind it. Default []
  • :at — the time in milliseconds an animated art's frame is chosen for. Default 0

Summary

Types

option()

Functions

project(atlas, point, opts)

Where world point {x, y} lands in the picture, or nil when it is behind the camera.

render(atlas, opts)

The picture, as the module documentation describes.

tile_at(atlas, point, opts)

The tile under picture pixel {px, py}, or nil at or above the horizon.

unproject(atlas, arg, opts)

The world point under picture pixel {px, py}, or nil at or above the horizon.

Types

option()

@type option() ::
  {:position, {number(), number()}}
  | {:heading, number()}
  | {:cell, ({integer(), integer()} -> Cauldron2D.Surface.cell())}
  | {:size, {pos_integer(), pos_integer()}}
  | {:eye, number()}
  | {:pitch, number()}
  | {:aspect, number()}
  | {:fov, number()}
  | {:range, number()}
  | {:sky, {{byte(), byte(), byte()}, {byte(), byte(), byte()}}}
  | {:movers, [tuple()]}
  | {:volumes, [map()]}
  | {:at, integer()}

Functions

project(atlas, point, opts)

@spec project(Cauldron2D.Atlas.name() | Cauldron2D.Atlas.t(), {number(), number()}, [
  option()
]) ::
  {float(), float()} | nil

Where world point {x, y} lands in the picture, or nil when it is behind the camera.

render(atlas, opts)

@spec render(Cauldron2D.Atlas.name() | Cauldron2D.Atlas.t(), [option()]) ::
  FrenchCurve.Raster.t()

The picture, as the module documentation describes.

tile_at(atlas, point, opts)

@spec tile_at(Cauldron2D.Atlas.name() | Cauldron2D.Atlas.t(), {number(), number()}, [
  option()
]) ::
  {integer(), integer()} | nil

The tile under picture pixel {px, py}, or nil at or above the horizon.

unproject(atlas, arg, opts)

@spec unproject(
  Cauldron2D.Atlas.name() | Cauldron2D.Atlas.t(),
  {number(), number()},
  [option()]
) ::
  {float(), float()} | nil

The world point under picture pixel {px, py}, or nil at or above the horizon.