flash on 2009-5-30

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favorite:3
lines:140
license : MIT License
modified : 2009-05-30 21:14:48

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package
{
   import flash.display.Graphics;
   import flash.display.Sprite;
   import flash.events.MouseEvent;
   import flash.geom.Point;
   import flash.geom.Rectangle;
   import flash.text.TextField;
   import flash.text.TextFormat;
   import flash.utils.getTimer;
   [SWF(frameRate="100", backgroundColor="0x000000", width="500", height="500")]

public class TriangleAABBSpeedTest extends Sprite
   {
      
      
      public var outputText : TextField;
      
      public function TriangleAABBSpeedTest()
      {
         super();
         outputText = new TextField(); 
         x = y = 250; 
         outputText.defaultTextFormat = new TextFormat("Arial"); 
         outputText.textColor = 0xffffff; 
         outputText.text = "Click to start test"; 
         outputText.x = outputText.y = -250; 
         outputText.width = 500; 
         
         addChild(outputText); 
         
         stage.addEventListener(MouseEvent.MOUSE_DOWN, startTest); 
         
      }
   
      // I'm thinking that storing these values as properties rather than declaring them as local vars 
      // should be faster...
         
      private  var x0 : Number; 
      private  var y0 : Number; 
      private  var x1 : Number; 
      private  var y1 : Number; 
      private  var x2 : Number; 
      private  var y2 : Number; 
      private  var l : Number; 
      private  var r : Number; 
      private  var t : Number; 
      private  var b : Number; 
      
      private  var top_intersection:Number ;
      private  var bottom_intersection : Number; 
      private  var toptrianglepoint : Number; 
      private  var bottomtrianglepoint : Number; 
      
      private  var m: Number;
      private var c : Number   
   
   
      // THESE ARE THE TWO FUNCTIONS YOU CAN OPTIMISE. 
      // I realise that you could inline the lineRectangleIntersect method, but I'd rather not do that just yet... 
      // I'm looking for maths/logic improvements. 
   
      public function triangleAABBIntersectionTest(rect:Rectangle,  vertex0:Point, vertex1:Point, vertex2:Point ) : Boolean
      {
         // YOU MUST LEAVE THESE DECLARATIONS; they simulate necessary data exchange within PV3D
         l = rect.left; 
         r = rect.right; 
         t = rect.top; 
         b = rect.bottom; 
         
         x0 = vertex0.x; 
         y0 = vertex0.y; 
         x1 = vertex1.x; 
         y1 = vertex1.y; 
         x2 = vertex2.x; 
         y2 = vertex2.y; 
         
         
         return lineRectangleIntersect(x0,y0,x1,y1) 
               ||   lineRectangleIntersect(x1,y1,x2,y2) 
               ||   lineRectangleIntersect(x2,y2,x0,y0);
      
      
         
      }
      
      
      public function lineRectangleIntersect(x0: Number,y0: Number,x1: Number,y1: Number):Boolean //, left:Number, right:Number, top:Number, bottom:Number) : Boolean
      {
            
            // Calculate m and c for the equation for the line (y = mx+c)
            m = (y1-y0) / (x1-x0); 
            c = y0 -(m*x0);

// if the line is going up from right to left then the top intersect point is on the left
            if(m>0)
            {
               top_intersection = (m*l  + c); 
               bottom_intersection = (m*r  + c);
            } 
            // otherwise it's on the right
            else 
            {
               top_intersection = (m*r  + c); 
               bottom_intersection = (m*l  + c); 
            }
            
            // work out the top and bottom extents for the triangle
            if(y0<y1)
            {
               toptrianglepoint = y0; 
               bottomtrianglepoint = y1; 
            }
            else
            {
               toptrianglepoint = y1; 
               bottomtrianglepoint = y0; 
            }
            
            var topoverlap : Number; 
            var botoverlap : Number; 
            
            // and calculate the overlap between those two bounds
            topoverlap = top_intersection>toptrianglepoint ? top_intersection : toptrianglepoint; 
            botoverlap = bottom_intersection<bottomtrianglepoint ? bottom_intersection : bottomtrianglepoint; 
            
            // (topoverlap<botoverlap) : 
            // if the intersection isn't the right way up then we have no overlap
            
            // (!((botoverlap<t) || (topoverlap>b)) :
            // If the bottom overlap is higher than the top of the rectangle or the top overlap is 
            // lower than the bottom of the rectangle we don't have intersection. So return the negative 
            // of that. Much faster than checking each of the points is within the bounds of the rectangle. 
            return (topoverlap<botoverlap) && (!((botoverlap<t) || (topoverlap>b)));
         
      }

public function startTest(e:MouseEvent = null) : void
      {
         var g : Graphics = graphics; 
         g.clear(); 
         var cullingRect : Rectangle = new Rectangle(-100,-75,200,150); 
         
         var iterations : int = 100000; 
         var timerIntersecting : int = 0 ; 
         var timerNotIntersecting : int = 0 ; 
                        var intersectCount : int = 0; 
                        
         var v0 : Point = new Point(); 
         var v1 : Point = new Point(); 
         var v2 : Point = new Point(); 
         
         var i : int = iterations; 
         
         while(--i>-1)
         {
            v0.x = Math.random()*400 - 200; 
            v0.y = Math.random()*400 - 200; 
            v1.x = v0.x+ (Math.random()*300 -150); 
            v1.y = v0.y+ (Math.random()*300 -150); 
            v2.x = v0.x+ (Math.random()*300 -150); 
            v2.y = v0.y+ (Math.random()*300 -150);             
            
            var startTimer : int = getTimer(); 
            var intersecting : Boolean = triangleAABBIntersectionTest(cullingRect, v0, v1, v2); 
            if(intersecting)
            {
               timerIntersecting += (getTimer() - startTimer);
               intersectCount++; 
            }
            else 
            {
               timerNotIntersecting += (getTimer() - startTimer);
            }
            if(i<300)
            {
               g.lineStyle(0,0x000000); 
               g.beginFill(intersecting ? 0x006600 : 0x660000,0.5); 
               g.moveTo(x0,y0); 
               g.lineTo(x1,y1); 
               g.lineTo(x2,y2); 
               g.lineTo(x0,y0); 
               g.endFill(); 
            }
         }
         
         g.lineStyle(0,0xffffff,0.5); 
         g.drawRect(cullingRect.x, cullingRect.y, cullingRect.width, cullingRect.height); 
         outputText.text = "Average time per triangle : "+(timerIntersecting+timerNotIntersecting)/iterations; 
         outputText.appendText("\nAverage time per intersecting triangle : "+(timerIntersecting)/intersectCount); 
         outputText.appendText("\nAverage time per non-intersecting triangle : "+(timerNotIntersecting)/(iterations-intersectCount));

}
   
   
      
      
   }
}

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