Game.LambdaHack.Common.Point

Basic operations on 2D points represented as linear offsets.

Documentation

data Point

The type of positions 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 EnumMap and cheaper array indexing, including cheaper bounds checks.

Instances

Enum Point

Eq Point

Ord Point

Show Point

Ix Point

Binary Point

Random Point

toPoint :: X -> PointXY -> Point

Conversion from cartesian coordinates to Point.

showPoint :: X -> Point -> Text

Print a point as a tuple of cartesian coordinates.

origin :: Point

The top-left corner position 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 positions of a given position.

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

Returns the 4, or less, surrounding positions in cardinal directions from a given position.

inside :: X -> Point -> (X, Y, X, Y) -> Bool

Checks that a point belongs to an area.

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

Calculate the displacement vector from a position 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.