Game.LambdaHack.Vector

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

Documentation

data Vector

2D vectors represented as offsets in the linear framebuffer indexed by Point.

A newtype is used to prevent mixing up the type with Point itself. Note that the offset representations of a vector is usually not unique. E.g., for vectors of length 1 in the chessboard metric, used to denote geographical directions, the representations are pairwise distinct if and only if the level width and height are at least 3.

Instances

Eq Vector

Show Vector

Binary Vector

toVector :: X -> VectorXY -> Vector

Converts a vector in cartesian representation into Vector.

shift :: Point -> Vector -> Point

Translate a point by a vector.

Particularly simple and fast implementation in the linear representation.

shiftBounded :: X -> Area -> Point -> Vector -> Point

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

moves :: X -> [Vector]

Vectors of all unit moves, clockwise, starting north-west.

movesWidth :: [X -> Vector]

Vectors of all unit moves, clockwise, starting north-west, parameterized by level width.

isUnit :: X -> Vector -> Bool

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

euclidDistSq :: X -> Vector -> Vector -> Int

Squared euclidean distance between two unit vectors.

diagonal :: X -> Vector -> Bool

Checks whether a unit vector is a diagonal direction, as opposed to cardinal.

neg :: Vector -> Vector

Reverse an arbirary vector.

towards :: X -> Point -> Point -> Vector

Given two distinct locations, 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..

displacement :: Point -> Point -> Vector

A vector from a point to another. We have

 shift loc1 (displacement loc1 loc2) == loc2

Particularly simple and fast implementation in the linear representation.

displacePath :: [Point] -> [Vector]

A list of vectors between a list of points.

shiftPath :: Point -> [Vector] -> [Point]

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