Graphics.Triangulation.Triangulation

Documentation

type Points = Array Int (Float, Float)

type TriangulationFunction = Points -> [Int] -> [(Int, Int, Int)]

data Tree

Constructors

Node Int Int [Tree]

Instances

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type F2 = (Float, Float)

triangulate :: TriangulationFunction -> Geometry -> Geometry

since there are a lot of triangulation algorithms a triangulation function can be passed

deleteHoles :: Geometry -> Geometry

some triangulation algorithms on't support polygons with holes These polygons with (nested) holes have to be cut so that they consist of only one outline I.e. the chars a,b,d,e,g,o,p,q contain holes tat have to be deleted.

embed :: Points -> [[Int]] -> [Int] -> [Int]

cut a polygon at a good position and insert the contained hole-polygon with opposite direction

alternate :: Int -> Bool -> [Int] -> [Int]

make sure that direction (clockwise or ccw) of polygons alternates depending on the nesting number c of poly

generateTrees :: Points -> (Points -> [Int] -> [Int] -> Bool) -> [[Int]] -> [Tree]

f should be the funtion to test contains the trees then are the hierarchy of containedness of outlines

treesList :: Points -> [[Int]] -> [Tree] -> [Tree]

insertTrees :: Points -> [Int] -> [Tree] -> [Tree]

insertTree :: Points -> [Int] -> Tree -> (Bool, Tree)

rotatePoly :: Int -> Points -> [Int] -> (Int, Float)

how many positions to rotate a polygon until the start point is nearest to some other point call i.e. with nearest (3,4) [(0,0),(1,2), ... ] 0 0

nearest :: F2 -> [F2] -> Float -> Int -> Int -> (Int, Float)

insidePoly :: Points -> [Int] -> [Int] -> Bool

returns True iff the first point of the first polygon is inside the second poylgon

pointInside :: F2 -> [F2] -> Bool

A point is inside a polygon if it has an odd number of intersections with the boundary (Jordan Curve theorem)

polygonDirection :: [F2] -> Bool

the direction of a polygon can be obtained by looking at a maximal point returns True if counterclockwise False if clockwise

isLeftTurn :: F2 -> F2 -> F2 -> Bool