Initial data commit

Task/Ray-casting-algorithm/Lua/ray-casting-algorithm.lua

@@ -0,0 +1,38 @@
+function Point(x,y) return {x=x, y=y} end
+
+function Polygon(name, points)
+  local function contains(self, p)
+    local odd, eps = false, 1e-9
+    local function rayseg(p, a, b)
+      if a.y > b.y then a, b = b, a end
+      if p.y == a.y or p.y == b.y then p.y = p.y + eps end
+      if p.y < a.y or p.y > b.y or p.x > math.max(a.x, b.x) then return false end
+      if p.x < math.min(a.x, b.x) then return true end
+      local red = a.x == b.x and math.huge or (b.y-a.y)/(b.x-a.x)
+      local blu = a.x == p.x and math.huge or (p.y-a.y)/(p.x-a.x)
+      return blu >= red
+     end
+    for i, a in ipairs(self.points) do
+      local b = self.points[i%#self.points+1]
+      if rayseg(p, a, b) then odd = not odd end
+    end
+    return odd
+  end
+  return {name=name, points=points, contains=contains}
+end
+
+polygons = {
+  Polygon("square", { Point(0,0), Point(10,0), Point(10,10), Point(0,10) }),
+  Polygon("squarehole", { Point(0,0), Point(10,0), Point(10,10), Point(0,10), Point(2.5,2.5), Point(7.5,2.5), Point(7.5,7.5), Point(2.5,7.5) }),
+  Polygon("strange", { Point(0,0), Point(2.5,2.5),  Point(0, 10), Point(2.5,7.5), Point(7.5,7.5), Point(10,10), Point(10,0), Point(2.5,2.5) }),
+  Polygon("hexagon", { Point(3,0), Point(7,0), Point(10,5), Point(7,10), Point(3,10), Point(0,5) })
+}
+points = { Point(5,5), Point(5,8), Point(-10,5), Point(0,5), Point(10,5), Point(8,5), Point(10,10) }
+
+for _,poly in ipairs(polygons) do
+  print("Does '"..poly.name.."' contain the point..")
+  for _,pt in ipairs(points) do
+    print(string.format("  (%3.f, %2.f)?  %s", pt.x, pt.y, tostring(poly:contains(pt))))
+  end
+  print()
+end