topical media & game development

talk show tell print

animation-ch08-OffsetSpring.ax

animation-ch08-OffsetSpring.ax [swf] [flash] flex


  package
  {
          import flash.display.Sprite;
          import flash.events.Event;
          
          public class @ax-animation-ch08-OffsetSpring extends Sprite
          {
                  private var ball:animation_ch08_Ball;
                  private var spring:Number = 0.1;
                  private var vx:Number = 0;
                  private var vy:Number = 0;
                  private var friction:Number = 0.95;
                  private var springLength:Number = 100;
                  
                  public function @ax-animation-ch08-OffsetSpring()
                  {
                          init();
                  }
                  
                  private function init():void
                  {
                          ball = new animation_ch08_Ball(20);
                          addChild(ball);
                          addEventListener(Event.ENTER_FRAME, onEnterFrame);
                  }
  
                  
                  private function onEnterFrame(event:Event):void
                  {
                          var dx:Number = ball.x - mouseX;
                          var dy:Number = ball.y - mouseY;
                          var angle:Number = Math.atan2(dy, dx);
                          var targetX:Number = mouseX + Math.cos(angle) * springLength;
                          var targetY:Number = mouseY + Math.sin(angle) * springLength;
                          vx += (targetX - ball.x) * spring;
                          vy += (targetY - ball.y) * spring;
                          vx *= friction;
                          vy *= friction;
                          ball.x += vx;
                          ball.y += vy;
                          graphics.clear();
                          graphics.lineStyle(1);
                          graphics.moveTo(ball.x, ball.y);
                          graphics.lineTo(mouseX, mouseY);
                  }
          }
  }
  


(C) Æliens 04/09/2009

You may not copy or print any of this material without explicit permission of the author or the publisher. In case of other copyright issues, contact the author.