forked from: forked from: Catmull-Rom Error

/**
 * Copyright fukt ( http://wonderfl.net/user/fukt )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/AmGT
 */

// forked from Altschuler's forked from: Catmull-Rom Error
// forked from shapevent's Catmull-Rom Error
package {

// CLICK and drag red dots to change the shape

    import flash.display.*;
    import flash.events.*;
    import flash.geom.*;


    [SWF(width = 500, height= 500)]

       import flash.utils.Dictionary;
       public class CatmullError extends MovieClip {
        private var pnts:Array;
        private var n : Number = 0;
        private var d : Dictionary = new Dictionary(true);

               public function CatmullError(){
                  // init
            pnts = new Array();
            // make 8 control points
            for (var i:int = 0; i<8; i++){
                pnts.push(dot(50 + Math.random() * 80 * i, Math.random()*(stage.stageHeight-40)+20));
                d[pnts[pnts.length-1]] = (stage.stageWidth / 2) - pnts[pnts.length-1].x + Math.random() * 100;
            }
            addEventListener(Event.ENTER_FRAME, onLoop);
            
            
            // all math from http://en.wikipedia.org/wiki/Cubic_Hermite_spline
            
            // draggable dot
            
            
            stage.addEventListener(MouseEvent.MOUSE_UP, onUp);
            stage.addEventListener(MouseEvent.MOUSE_DOWN,onDown);
            
            
            
            

               }
               // private methods

        private function onLoop(evt:Event):void {
            
            graphics.clear();
            graphics.lineStyle(0,0);
            curve(pnts); 
        }
        private function tangent(pk1:Sprite, pk_1:Sprite):Point{
            return new Point((pk1.x - pk_1.x) / 2, (pk1.y - pk_1.y) / 2);
        }
        private function curve(p:Array, res:Number=.05):void{
            var px:Number = 0;
            var py:Number = 0;
            var cx:Number = stage.stageWidth / 2;
            var cy:Number = stage.stageHeight / 2;
            var pIter:int = p.length - 1;
            var m:Array = [];
            m[0] = tangent(p[1], p[0]);
            for (var i:int = 1; i<pIter; i++){
                n+=.005;
                    p[i].x = cx + (Math.cos(n) * d[p[i]]);
                    p[i].y += (Math.sin(n));
                    //sp[i].y += Math.sin(i) * 2;
                m[i] = tangent(p[i + 1], p[i - 1]);
            }
            m[pIter] = tangent(p[pIter], p[pIter - 1]);
            for (var t:Number = 0; t <1; t+=res){
                 var t_2:Number = t * t;
                 var _1_t:Number = 1 - t;
                 var _2t:Number = 2 * t;
                 var h00:Number =  (1 + _2t) * (_1_t) * (_1_t);
                 var h10:Number =  t  * (_1_t) * (_1_t);
                 var h01:Number =  t_2 * (3 - _2t);
                 var h11:Number =  t_2 * (t - 1);
                 for (var k:int = 0; k <pIter; k++){
                     var k1:int = k + 1;
                     var pk:Sprite = p[k];
                     var pk1:Sprite = p[k1];
                     var mk:Point = m[k];
                     var mk1:Point = m[k1];
                    
                     px = h00 * pk.x + h10 * mk.x + h01 * pk1.x + h11 * mk1.x;
                     py = h00 * pk.y + h10 * mk.y + h01 * pk1.y + h11 * mk1.y;
                     if (k == 0){
                        graphics.moveTo(px, py); 
                     }else{
                        graphics.lineTo(px, py);
                     }
                     
                    // canvas.setPixel(px, py, 0xFFFFFF);
                 }
            }
        }
        private function dot(xp:Number, yp:Number, col:uint = 0xFF0000, rad:Number=4):Sprite {
            var s:Sprite = Sprite(addChild(new Sprite));
            s.x = xp;
            s.y = yp;
        
            with(s.graphics) beginFill(col), drawCircle(0,0,rad);
            s.buttonMode = true;
            s.addEventListener(MouseEvent.MOUSE_DOWN, onDrag);
            return s;
        }
        private function onDrag(evt:MouseEvent):void {
            evt.currentTarget.startDrag()
        }
        private function onDown(evt:MouseEvent):void{
              dotsVisible(false);
        }
        private function onUp(evt:MouseEvent):void{
            stopDrag();
            dotsVisible(true);
        }
        private function dotsVisible(bool:Boolean):void{
            for (var i:int = 0; i<pnts.length; i++){
              pnts[i].visible = bool;
             }
        }
        

       }

}