fixed pointer bug

src/org/poly2tri/MonoToneMountain.scala

@@ -43,8 +43,6 @@ class MonotoneMountain {
 	val monoPoly = new ArrayBuffer[Point]
     // Triangles that constitute the mountain
 	val triangles = new ArrayBuffer[Array[Point]]
-	      
-	var angle = 0f
  
 	// Append a point to the list
 	def +=(point: Point) {
@@ -123,16 +121,17 @@ class MonotoneMountain {
 	private def convex(p: Point) = {
 	  val a = (p.next - p) 
 	  val b = (p.prev - p) 
-      angle = Math.atan2(b.y,b.x).toFloat - Math.atan2(a.y,a.x).toFloat
-      if(angle < 0) while(angle < -Math.Pi) angle += Math.Pi.toFloat
-      if(angle > 0) while(angle > Math.Pi) angle -= Math.Pi.toFloat
+      var angle = Math.atan2(b.y,b.x) - Math.atan2(a.y,a.x)
+      if(angle < 0) while(angle < -Math.Pi) angle += Math.Pi
+      if(angle > 0) while(angle > Math.Pi) angle -= Math.Pi
       // For numerical robustness....
-      angle = 0.01f * Math.round( angle * 10.0f)
+      angle = 0.1 * Math.round( angle * 10.0)
+      val cvx = (angle < 0)
       if(p.y >= head.y) {
-        (angle < 0)
+        cvx
       } else {
-        !(angle < 0)
-      }
+        !cvx
+      } 
     }
 
 	private def lastTriangle {

src/org/poly2tri/Poly2Tri.scala

@@ -59,6 +59,7 @@ class Poly2TriDemo extends BasicGame("Poly2Tri") {
   var quit = false
   var debug = false
   var drawMap = false
+  var hiLighter = 0
   
   def init(container: GameContainer) {
     snake
@@ -92,11 +93,14 @@ class Poly2TriDemo extends BasicGame("Poly2Tri") {
    }
    
    if(!debug) {
+    var i = 0
     for(t <- tesselator.triangles) {
         val triangle = new Polygon
         t.foreach(p => triangle.addPoint(p.x, p.y))
-        g.setColor(red)
+        val color = if(i == hiLighter) blue else red
+        g.setColor(color)
         g.draw(triangle)
+        i += 1
       }
    } else {
     for(mp <- tesselator.monoPolies) {
@@ -110,12 +114,27 @@ class Poly2TriDemo extends BasicGame("Poly2Tri") {
   }
   
   override def keyPressed(key:Int, c:Char) {
+    // ESC
     if(key == 1) quit = true
+    // SPACE
     if(key == 57) debug = !debug
+    // UP
+    if(key == 200) {
+      hiLighter += 1
+      if (hiLighter == tesselator.triangles.size)
+        hiLighter = 0
+    }
+    // DOWN
+    if(key == 208) {
+      hiLighter -= 1
+      if (hiLighter == -1)
+        hiLighter = tesselator.triangles.size-1
+    }
     if(c == 'm') drawMap = !drawMap
-    if(c == '1') poly
-    if(c == '2') snake
-    if(c == '3') star
+    if(c == '1') {poly; hiLighter = 0}
+    if(c == '2') {snake; hiLighter = 0}
+    if(c == '3') {star; hiLighter = 0}
+
   }
   
   // Test #1
@@ -143,18 +162,16 @@ class Poly2TriDemo extends BasicGame("Poly2Tri") {
   
   def star {
 	
-	val scale = 1.0f
-    val displace = 0f
-    val p1 = new Point(350,75)*scale+displace
-    val p2 = new Point(379,161)*scale+displace
-    val p3 = new Point(469,161)*scale+displace
-    val p4 = new Point(397,215)*scale+displace
-    val p5 = new Point(423,301)*scale+displace
-    val p6 = new Point(350,250)*scale+displace
-    val p7 = new Point(277,301)*scale+displace
-    val p8 = new Point(303,215)*scale+displace
-    val p9 = new Point(231,161)*scale+displace
-    val p10 = new Point(321,161)*scale+displace
+    val p1 = new Point(350,75)
+    val p2 = new Point(379,161)
+    val p3 = new Point(469,161)
+    val p4 = new Point(397,215)
+    val p5 = new Point(423,301)
+    val p6 = new Point(350,250)
+    val p7 = new Point(277,301)
+    val p8 = new Point(303,215)
+    val p9 = new Point(231,161)
+    val p10 = new Point(321,161)
     
     val segments = new ArrayBuffer[Segment]
     segments += new Segment(p1, p2)

src/org/poly2tri/QueryGraph.scala

@@ -48,7 +48,7 @@ class QueryGraph(var head: Node) {
 	      if(s > trapezoids(j).rightPoint) {
 	        trapezoids += trapezoids(j).upperRight
 	      } else {
-	        trapezoids += trapezoids(j).lowerRight
+	          trapezoids += trapezoids(j).lowerRight
 	      }
 	      j += 1
 	    }

src/org/poly2tri/Trapezoid.scala

@@ -41,18 +41,21 @@ class Trapezoid(val leftPoint: Point, var rightPoint: Point, val top: Segment, v
   var upperRight: Trapezoid = null
   var lowerRight: Trapezoid = null
   
-  def updateNeighbors(ul: Trapezoid, ll: Trapezoid, ur: Trapezoid, lr: Trapezoid) {
+  def updateLeftNeighbors(ul: Trapezoid, ll: Trapezoid) {
     if(upperLeft != null && upperLeft.top == top) upperLeft.upperRight = ul
     if(lowerLeft != null && lowerLeft.bottom == bottom) lowerLeft.lowerRight = ll
+  }
+  
+  def updateRightNeighbors(ur: Trapezoid, lr: Trapezoid) {
     if(upperRight != null && upperRight.top == top) upperRight.upperLeft = ur
     if(lowerRight != null && lowerRight.bottom == bottom) lowerRight.lowerLeft = lr
   }
   
   def update(ul: Trapezoid, ll: Trapezoid, ur: Trapezoid, lr: Trapezoid) {
-    upperLeft = ul
-    lowerLeft = ll
-    upperRight = ur
-    lowerRight = lr
+    upperLeft = ul; if(ul != null) ul.upperRight = this
+    lowerLeft = ll; if(ll != null) ll.lowerRight = this
+    upperRight = ur; if(ur != null) ur.upperLeft = this
+    lowerRight = lr; if(lr != null) lr.lowerLeft = this    
   }
   
   def markNeighbors {

src/org/poly2tri/TrapezoidalMap.scala

@@ -81,7 +81,6 @@ class TrapezoidalMap {
     s.above = trapezoids(1)
     s.below = trapezoids(2)
     
-    t.updateNeighbors(trapezoids(0), trapezoids(0), trapezoids(3), trapezoids(3))
     trapezoids
   }
 
@@ -105,7 +104,6 @@ class TrapezoidalMap {
     s.above = trapezoids(1)
     s.below = trapezoids(2)
     
-    t.updateNeighbors(trapezoids(0), trapezoids(0), trapezoids(1), trapezoids(2))
     trapezoids
   }
   
@@ -126,18 +124,18 @@ class TrapezoidalMap {
     
     if(topCross) {
       trapezoids(0).upperRight = t.upperRight
-      trapezoids(0).rightPoint = t.rightPoint
+      if(t.upperRight != null) t.upperRight.upperLeft = trapezoids(0)
+      trapezoids(0).rightPoint = rp
     } else {
       trapezoids(0).update(t.upperLeft, s.above, t.upperRight, null)
-      if(s.above != null) s.above.lowerRight = trapezoids(0)
     }
     
     if(bottomCross) {
       trapezoids(1).lowerRight = t.lowerRight
-      trapezoids(1).rightPoint = t.rightPoint
+      if(t.lowerRight != null) t.lowerRight.lowerLeft = trapezoids(1)
+      trapezoids(1).rightPoint = rp
     } else {
       trapezoids(1).update(s.below, t.lowerLeft, null, t.lowerRight)
-      if(s.below != null) s.below.upperRight = trapezoids(1)
     }
     
     bCross = t.bottom
@@ -145,7 +143,6 @@ class TrapezoidalMap {
     s.above = trapezoids(0)
     s.below = trapezoids(1)
     
-    t.updateNeighbors(trapezoids(0), trapezoids(1), trapezoids(0), trapezoids(1))
     trapezoids
   }
   
@@ -168,7 +165,6 @@ class TrapezoidalMap {
       trapezoids(0).rightPoint = s.q
     } else {
       trapezoids(0).update(t.upperLeft, s.above, trapezoids(2), null)
-      if(s.above != null) s.above.lowerRight = trapezoids(0)
     }
     
     if(bottomCross) {
@@ -176,14 +172,10 @@ class TrapezoidalMap {
       trapezoids(1).rightPoint = s.q
     } else {
       trapezoids(1).update(s.below, t.lowerLeft, null, trapezoids(2))
-      if(s.below != null) s.below.upperRight = trapezoids(1)
     }
+    
     trapezoids(2).update(trapezoids(0), trapezoids(1), t.upperRight, t.lowerRight)
     
-    s.above = trapezoids(0)
-    s.below = trapezoids(1)
-    
-    t.updateNeighbors(trapezoids(0), trapezoids(1), trapezoids(2), trapezoids(2))
     trapezoids
   }
   

src/org/poly2tri/Triangulator.scala

@@ -36,11 +36,12 @@ import scala.collection.mutable.ArrayBuffer
 // algorithm for computing trapezoidal decompositions and for triangulating polygons"
 class Triangulator(var segments: ArrayBuffer[Segment]) {
   
-  // Trapezoid decomposition list
-  var trapezoids : ArrayBuffer[Trapezoid] = null
   // Triangle decomposition list
   var triangles = new ArrayBuffer[Array[Point]]
   
+  // Order and randomize the segments
+  segments = orderSegments
+  
   // Build the trapezoidal map and query graph
   def process {
     
@@ -81,10 +82,14 @@ class Triangulator(var segments: ArrayBuffer[Segment]) {
     for(i <- 0 until xMonoPoly.size)
       for(t <- xMonoPoly(i).triangles)
     	  triangles += t
+    
+    println("# triangles = " + triangles.size)
   }
   
-  // For debugging
+  // The trapezoidal map 
   def trapezoidMap = trapezoidalMap.map
+  // Trapezoid decomposition list
+  var trapezoids : ArrayBuffer[Trapezoid] = null
   // Monotone polygons - these are monotone mountains
   def monoPolies: ArrayBuffer[ArrayBuffer[Point]] = {
     val polies = new ArrayBuffer[ArrayBuffer[Point]]
@@ -99,8 +104,6 @@ class Triangulator(var segments: ArrayBuffer[Segment]) {
   private val queryGraph = new QueryGraph(new Sink(boundingBox))
   private val xMonoPoly = new ArrayBuffer[MonotoneMountain]
                                         
-  segments = orderSegments
-  
   // Build a list of x-monotone mountains
   private def createMountains {
     for(s <- segments) {
@@ -143,9 +146,8 @@ class Triangulator(var segments: ArrayBuffer[Segment]) {
         s.p = s.q
         s.q = tmp
         segs += s
-      } else if(s.p.x < s.q.x) {
-        segs += s
-      }
+      } else if(s.p.x < s.q.x)
+          segs += s
     }
     // This is actually important: See Seidel's paper
     Random.shuffle(segs)