fixed orientation bug

src/org/poly2tri/cdt/CDT.scala

@@ -124,7 +124,7 @@ class CDT(val points: List[Point], val segments: List[Segment], iTriangle: Trian
   
   // Implement sweep-line 
   private def sweep {
-    for(i <- 1 until 10 /*points.size*/) {
+    for(i <- 1 until points.size) {
       val point = points(i)
       // Process Point event
       val triangle = pointEvent(point)
@@ -334,9 +334,21 @@ class CDT(val points: List[Point], val segments: List[Segment], iTriangle: Trian
       val v2 = p1 - p2
       val v3 = p1 - p4
       val v4 = p3 - p4
-      if((v1 dot v2) < 0 && (v3 dot v4) < 0)
-        true 
-      else 
+      
+      val cosA = v1 dot v2
+      val cosB = v3 dot v4
+      
+      if(cosA < 0 && cosB < 0)
+        return true 
+      else if(cosA > 0 && cosB > 0)
+        return false
+      
+      val sinA = v1 cross v2
+      val sinB = v3 cross v4
+      
+      if(cosA*sinB + sinA*cosB < -0.01f)
+        true
+      else
         false
   }
   

src/org/poly2tri/shapes/Triangle.scala

@@ -118,13 +118,26 @@ class Triangle(val points: Array[Point], val neighbors: Array[Triangle]) {
   
   // Locate next triangle crossed by constraied edge
   def findNeighbor(e: Point): Triangle = {
-    var sameSign = Math.signum(ik cross e) == Math.signum(ij cross e)
-    if(!sameSign) return neighbors(0)
-    sameSign = Math.signum(jk cross e) == Math.signum(ji cross e)
-    if(!sameSign) return neighbors(1)
-    sameSign = Math.signum(kj cross e) == Math.signum(ki cross e)
-    if(!sameSign) return neighbors(2)
-    this
+    if(orient(points(0), points(1), e) > 0)
+      return neighbors(2)
+    if(orient(points(1), points(2), e) > 0)
+      return neighbors(0)
+    if(orient(points(2), points(0), e) > 0)
+      return neighbors(1)
+    else
+      // Point must reside inside this triangle
+      this
+  }
+  
+  // Return: positive if point p is left of ab
+  //         negative if point p is right of ab
+  //         zero if points are colinear
+  def orient(b: Point, a: Point, p: Point): Float = {
+    val acx = a.x - p.x
+    val bcx = b.x - p.x
+    val acy = a.y - p.y
+    val bcy = b.y - p.y
+    acx * bcy - acy * bcx  
   }
   
   // The neighbor CW to given point