Game.LambdaHack.Point

Basic operations on 2D points represented as linear offsets.

Documentation

type Point = Int

The type of locations on the 2D level map, heavily optimized.

We represent the (level map on the) screen as a linear framebuffer, where Point is an Int offset counted from the first cell. We do bounds check for the X size whenever we convert between representations and each subsequent array access performs another check, effectively for Y size. After dungeon is generated (using PointXY, not Point), and converted to the Point representation, points are used mainly as keys and not constructed often, so the performance will improve due to smaller save files, the use of IntMap and cheaper array indexing, including cheaper bounds checks. We don't define Point as a newtype to avoid the trouble with using EnumMap in place of IntMap, etc.

toPoint :: X -> PointXY -> Point

Conversion from cartesian coordinates to Point.

showPoint :: X -> Point -> String

Print a point as a tuple of cartesian coordinates.

origin :: Point

The top-left corner location of the level.

chessDist :: X -> Point -> Point -> Int

The distance between two points in the chessboard metric.

adjacent :: X -> Point -> Point -> Bool

Checks whether two points are adjacent on the map (horizontally, vertically or diagonally).

vicinity :: X -> Y -> Point -> [Point]

Returns the 8, or less, surrounding locations of a given location.

vicinityCardinal :: X -> Y -> Point -> [Point]

Returns the 4, or less, surrounding locations in cardinal directions from a given location.

inside :: X -> Point -> Area -> Bool

Checks that a point belongs to an area.

displacementXYZ :: X -> Point -> Point -> VectorXY

Calculate the displacement vector from a location to another.

bla :: X -> Y -> Int -> Point -> Point -> Maybe [Point]

Bresenham's line algorithm generalized to arbitrary starting eps (eps value of 0 gives the standard BLA). Skips the source point and goes through the second point to the edge of the level. GIves Nothing if the points are equal.