bug hunting

src/org/poly2tri/Poly2Tri.scala

@@ -84,7 +84,7 @@ class Poly2TriDemo extends BasicGame("Poly2Tri") {
   val strange = "data/strange.dat"
   val i18 = "data/i.18"
   
-  var currentModel = strange
+  var currentModel = nazcaMonkey
   
   var mouseButton = 0
   var mousePressed = false
@@ -264,7 +264,7 @@ class Poly2TriDemo extends BasicGame("Poly2Tri") {
     if(c == '5') selectModel(star)
     if(c == '6') selectModel(i18)
     if(c == 's') drawSegs = !drawSegs
-    if(c == 'e') {drawEarClip = !drawEarClip; selectModel(currentModel)}
+    //if(c == 'e') {drawEarClip = !drawEarClip; selectModel(currentModel)}
   }
     
   def selectModel(model: String) {

src/org/poly2tri/cdt/CDT.scala

@@ -126,14 +126,16 @@ class CDT(val points: List[Point], val segments: List[Segment], iTriangle: Trian
   // Implement sweep-line 
   private def sweep {
     //var cTri: Triangle = null
-    for(i <- 1 until points.size) {
+    for(i <- 1 until 15 /*points.size*/) {
       val point = points(i)
       // Process Point event
       var triangle: Triangle = null
       try {
         triangle = pointEvent(point)
       } catch {
-        case e: Exception => println("Offending triangle = " + i)
+        case e: Exception => 
+          println("Offending triangle = " + i)
+          //System exit 0
       }
       // Process edge events
       //point.edges.foreach(e => edgeEvent(e, triangle))
@@ -147,6 +149,9 @@ class CDT(val points: List[Point], val segments: List[Segment], iTriangle: Trian
     
     val node = aFront.locate(point)
 
+    // Avoid triangles that are almost collinear
+    if(!Util.collinear(point, node.point, node.next.point)) {
+    
     // Projected point coincides with existing point; create two triangles
     if(point.x == node.point.x && node.prev != null) {
         
@@ -198,9 +203,7 @@ class CDT(val points: List[Point], val segments: List[Segment], iTriangle: Trian
         if(legal) { 
           newNode = aFront.insert(point, triangle, node)
           // Update neighbors
-          println(1)
           nTri.updateNeighbors(cwPoint, ccwPoint, triangle, mesh.debug)
-          println(2)
         } else {
           newNode = new Node(triangle.points(1), triangle)
           val rNode = node.next
@@ -214,6 +217,11 @@ class CDT(val points: List[Point], val segments: List[Segment], iTriangle: Trian
 	    scanAFront(newNode)
 	    newNode.triangle
 	}
+    
+    } else {
+      println("bad triangle")
+      null
+    }
   }
   
   // EdgeEvent
@@ -404,9 +412,9 @@ class CDT(val points: List[Point], val segments: List[Segment], iTriangle: Trian
       
       val sinA = v1 cross v2
       val sinB = v3 cross v4
-      
+      //println((cosA*sinB + sinA*cosB))
       // Some small number
-      if((cosA*sinB + sinA*cosB) < -0.1) 
+      if((cosA*sinB + sinA*cosB) < -10f) 
         true
       else
         false

src/org/poly2tri/shapes/Triangle.scala

@@ -56,7 +56,7 @@ class Triangle(val points: Array[Point], val neighbors: Array[Triangle]) {
       mesh += triangle
       println(ccwPoint + "," + cwPoint)
       printDebug
-      //throw new Exception("Neighbor update error")
+      throw new Exception("Neighbor update error")
     }
   }
   

src/org/poly2tri/utils/Util.scala

@@ -7,6 +7,8 @@ import shapes.Point
 
 object Util {
   
+  val COLLINEAR_SLOP = 10f
+  
   // From "Scala By Example," by Martin Odersky
   def msort[A](less: (A, A) => Boolean)(xs: List[A]): List[A] = {
     def merge(xs1: List[A], xs2: List[A]): List[A] =
@@ -33,6 +35,34 @@ object Util {
 	 }
 	 xs
   }
+  
+  // Tests if the given points are collinear
+  def collinear(p1: Point, p2: Point, p3: Point): Boolean = {
+    
+    // 3x3 matrix
+    val a11 = p1.x
+    val a12 = p1.y
+    val a13 = 1f
+    val a21 = p2.x
+    val a22 = p2.y
+    val a23 = 1f
+    val a31 = p3.x
+    val a32 = p3.y
+    val a33 = 1f
+    
+    // Determinant
+    val d = a11*(a22*a33 - a32*a23) - a12*(a21*a33-a31*a23) + a13*(a21*a32-a31*a22)
+    
+    println("Determinant = " + d)
+    
+    if(d <= COLLINEAR_SLOP) {
+      true
+    } else {
+      false
+    }
+    
+  }
+  
 }
 
 /** The object <code>Random</code> offers a default implementation