tasks a-s

Task/Ray-casting-algorithm/CoffeeScript/ray-casting-algorithm.coffeescript

@@ -0,0 +1,28 @@
+  Point = (@x,@y) ->
+
+  pointInPoly = (point,poly) ->
+    segments = for pointA, index in poly
+                 pointB = poly[(index + 1) % poly.length]
+                 [pointA,pointB]
+    intesected = (segment for segment in segments when rayIntesectsSegment(point,segment))
+    intesected.length % 2 != 0
+
+  rayIntesectsSegment = (p,segment) ->
+    [p1,p2] = segment
+    [a,b] = if p1.y < p2.y
+              [p1,p2]
+            else
+              [p2,p1]
+    if p.y == b.y || p.y == a.y
+      p.y += Number.MIN_VALUE
+
+    if p.y > b.y || p.y < a.y
+      false
+    else if p.x > a.x && p.x > b.x
+      false
+    else if p.x < a.x && p.x < b.x
+      true
+    else
+      mAB = (b.y - a.y) / (b.x - a.x)
+      mAP = (p.y - a.y) / (p.x - a.x)
+      mAP > mAB