Game.LambdaHack.Common.Vector

Basic operations on 2D vectors represented in an efficient, but not unique, way.

Documentation

data Vector

2D vectors in cartesian representation. Coordinates grow to the right and down, so that the (1, 1) vector points to the bottom-right corner of the screen.

Constructors

Vector

Fields

vx :: !X

vy :: !Y

Instances

Enum Vector

Eq Vector

Ord Vector

Read Vector

Show Vector

Binary Vector

isUnit :: Vector -> Bool

Tells if a vector has length 1 in the chessboard metric.

isDiagonal :: Vector -> Bool

Checks whether a unit vector is a diagonal direction, as opposed to cardinal. If the vector is not unit, it checks that the vector is not horizontal nor vertical.

neg :: Vector -> Vector

Reverse an arbirary vector.

chessDistVector :: Vector -> Int

The lenght of a vector in the chessboard metric, where diagonal moves cost 1.

euclidDistSqVector :: Vector -> Vector -> Int

Squared euclidean distance between two vectors.

moves :: [Vector]

Vectors of all unit moves in the chessboard metric, clockwise, starting north-west.

movesCardinal :: [Vector]

Vectors of all cardinal direction unit moves, clockwise, starting north.

movesDiagonal :: [Vector]

Vectors of all diagonal direction unit moves, clockwise, starting north.

compassText :: Vector -> Text

vicinity

Arguments

:: X

-> Y

limit the search to this area

-> Point

position to find neighbours of

-> [Point]

All (8 at most) closest neighbours of a point within an area.

vicinityCardinal

Arguments

:: X

-> Y

limit the search to this area

-> Point

position to find neighbours of

-> [Point]

All (4 at most) cardinal direction neighbours of a point within an area.

shift :: Point -> Vector -> Point

Translate a point by a vector.

shiftBounded :: X -> Y -> Point -> Vector -> Point

Translate a point by a vector, but only if the result fits in an area.

trajectoryToPath :: Point -> [Vector] -> [Point]

A list of points that a list of vectors leads to.

trajectoryToPathBounded :: X -> Y -> Point -> [Vector] -> [Point]

A list of points that a list of vectors leads to, bounded by level size.

vectorToFrom :: Point -> Point -> Vector

The vector between the second point and the first. We have

shift pos1 (pos2 `vectorToFrom` pos1) == pos2

The arguments are in the same order as in the underlying scalar subtraction.

pathToTrajectory :: [Point] -> [Vector]

A list of vectors between a list of points.

type RadianAngle = Double

rotate :: RadianAngle -> Vector -> Vector

Rotate a vector by the given angle (expressed in radians) counterclockwise and return a unit vector approximately in the resulting direction.

towards :: Point -> Point -> Vector

Given two distinct positions, determine the direction (a unit vector) in which one should move from the first in order to get closer to the second. Ignores obstacles. Of several equally good directions (in the chessboard metric) it picks one of those that visually (in the euclidean metric) maximally align with the vector between the two points.