June 2018 Update

Task/Ray-casting-algorithm/Visual-Basic-.NET/ray-casting-algorithm.visual

@@ -0,0 +1,47 @@
+Imports System.Math
+
+Module RayCasting
+
+    Private square As Integer()() = {New Integer() {0, 0}, New Integer() {20, 0}, New Integer() {20, 20}, New Integer() {0, 20}}
+    Private squareHole As Integer()() = {New Integer() {0, 0}, New Integer() {20, 0}, New Integer() {20, 20}, New Integer() {0, 20}, New Integer() {5, 5}, New Integer() {15, 5}, New Integer() {15, 15}, New Integer() {5, 15}}
+    Private strange As Integer()() = {New Integer() {0, 0}, New Integer() {5, 5}, New Integer() {0, 20}, New Integer() {5, 15}, New Integer() {15, 15}, New Integer() {20, 20}, New Integer() {20, 0}}
+    Private hexagon As Integer()() = {New Integer() {6, 0}, New Integer() {14, 0}, New Integer() {20, 10}, New Integer() {14, 20}, New Integer() {6, 20}, New Integer() {0, 10}}
+    Private shapes As Integer()()() = {square, squareHole, strange, hexagon}
+
+    Public Sub Main()
+        Dim testPoints As Double()() = {New Double() {10, 10}, New Double() {10, 16}, New Double() {-20, 10}, New Double() {0, 10}, New Double() {20, 10}, New Double() {16, 10}, New Double() {20, 20}}
+
+        For Each shape As Integer()() In shapes
+            For Each point As Double() In testPoints
+                Console.Write(String.Format("{0} ", Contains(shape, point).ToString.PadLeft(7)))
+            Next
+            Console.WriteLine()
+        Next
+    End Sub
+
+    Private Function Contains(shape As Integer()(), point As Double()) As Boolean
+
+        Dim inside As Boolean = False
+        Dim length As Integer = shape.Length
+
+        For i As Integer = 0 To length - 1
+            If Intersects(shape(i), shape((i + 1) Mod length), point) Then
+                inside = Not inside
+            End If
+        Next
+
+        Return inside
+    End Function
+
+    Private Function Intersects(a As Integer(), b As Integer(), p As Double()) As Boolean
+
+        If a(1) > b(1) Then Return Intersects(b, a, p)
+        If p(1) = a(1) Or p(1) = b(1) Then p(1) += 0.0001
+        If p(1) > b(1) Or p(1) < a(1) Or p(0) > Max(a(0), b(0)) Then Return False
+        If p(0) < Min(a(0), b(0)) Then Return True
+        Dim red As Double = (p(1) - a(1)) / (p(0) - a(0))
+        Dim blue As Double = (b(1) - a(1)) / (b(0) - a(0))
+
+        Return red >= blue
+    End Function
+End Module