Game.LambdaHack.Server.Fov.Permissive

PFOV (Permissive Field of View) clean-room reimplemented based on the algorithm described in http://roguebasin.roguelikedevelopment.org/index.php?title=Precise_Permissive_Field_of_View, though the general structure is more influenced by recursive shadow casting, as implemented in Shadow.hs. In the result, this algorithm is much faster than the original algorithm on dense maps, since it does not scan areas blocked by shadows.

Documentation

scan

Arguments

:: (Bump -> Bool)

clear tile predicate

-> [Bump]

Calculates the list of tiles, in Bump coordinates, visible from (0, 0).

dline :: Bump -> Bump -> Line

Create a line from two points. Debug: check if well-defined.

dsteeper :: Bump -> Bump -> Bump -> Bool

Compare steepness of (p1, f) and (p2, f). Debug: Verify that the results of 2 independent checks are equal.

intersect :: Line -> Distance -> (Int, Int)

The Y coordinate, represented as a fraction, of the intersection of a given line and the line of diagonals of squares at distance d from (0, 0).

debugSteeper :: Bump -> Bump -> Bump -> Bool

Debug functions for PFOV:

Debug: calculate steeper for PFOV in another way and compare results.

debugLine :: Line -> (Bool, String)

Debug: checks postconditions of borderLine.