package {
    import flash.display.Sprite;
    import flash.display.StageScaleMode;
    import flash.display.StageAlign;
    import flash.display.Stage;
    import flash.events.Event;
    import flash.geom.Point;
    public class RealWalk extends Sprite {
         
        private var segment0:Segment;//大腿1
        private var segment1:Segment;//小腿1
        private var segment2:Segment;//大腿2
        private var segment3:Segment;//小腿2
         
        //各控制滑块
        private var speedSlider:SimpleSlider;
        private var thighRangeSlider:SimpleSlider;
        private var thighBaseSlider:SimpleSlider;
        private var calfRangeSlider:SimpleSlider;
        private var calfOffsetSlider:SimpleSlider;
        private var gravitySlider:SimpleSlider;
         
        private var cycle:Number=0;
        private var vx:Number=0;
        private var vy:Number=0;
 
        public function RealWalk() {
            init();
        }
 
        private function init():void {
            stage.scaleMode = StageScaleMode.NO_SCALE;
            stage.align = StageAlign.TOP_LEFT;
            segment0=new Segment(50,15);
            addChild(segment0);
            segment0.x=200;
            segment0.y=100;
             
            segment1=new Segment(50,10);
            addChild(segment1);
            segment1.x=segment0.getPin().x;
            segment1.y=segment0.getPin().y;
             
            segment2=new Segment(50,15);
            addChild(segment2);
            segment2.x=200;
            segment2.y=100;
             
            segment3=new Segment(50,10);
            addChild(segment3);
            segment3.x=segment2.getPin().x;
            segment3.y=segment2.getPin().y;
             
            speedSlider=new SimpleSlider(0,0.3,0.12);
            addChild(speedSlider);
            speedSlider.x=10;
            speedSlider.y=10;
             
            thighRangeSlider=new SimpleSlider(0,90,45);
            addChild(thighRangeSlider);
            thighRangeSlider.x=30;
            thighRangeSlider.y=10;
             
            thighBaseSlider=new SimpleSlider(0,180,90);
            addChild(thighBaseSlider);
            thighBaseSlider.x=50;
            thighBaseSlider.y=10;
             
            calfRangeSlider=new SimpleSlider(0,90,45);
            addChild(calfRangeSlider);
            calfRangeSlider.x=70;
            calfRangeSlider.y=10;
             
            calfOffsetSlider=new SimpleSlider(-3.14,3.14,-1.57);
            addChild(calfOffsetSlider);
            calfOffsetSlider.x=90;
            calfOffsetSlider.y=10;
             
            gravitySlider=new SimpleSlider(0,1,0.2);
            addChild(gravitySlider);
            gravitySlider.x=110;
            gravitySlider.y=10;
             
            addEventListener(Event.ENTER_FRAME, EnterFrameHandler);
        }
         
        private function EnterFrameHandler(event:Event):void {
            doVelocity();
            walk(segment0, segment1, cycle);
            walk(segment2, segment3, cycle + Math.PI);
            cycle+=speedSlider.value;
            checkFloor(segment1);
            checkFloor(segment3);
            checkWalls();
        }
         
        //行走姿态的处理
        private function walk(segA:Segment, segB:Segment,cyc:Number):void {
            var foot:Point=segB.getPin();
            var angleA:Number = Math.sin(cyc) *thighRangeSlider.value +thighBaseSlider.value;
            var angleB:Number = Math.sin(cyc +calfOffsetSlider.value) *calfRangeSlider.value +calfRangeSlider.value;
            segA.rotation=angleA;
            segB.rotation=segA.rotation+angleB;
            segB.x=segA.getPin().x;
            segB.y=segA.getPin().y;
            segB.vx=segB.getPin().x-foot.x;
            segB.vy=segB.getPin().y-foot.y;
        }
         
        //下肢的速度处理
        private function doVelocity():void {
            vy+=gravitySlider.value;
            //因为小腿是跟着大腿的，所以只要处理大腿的速度即可
            segment0.x+=vx;
            segment0.y+=vy;
            segment2.x+=vx;
            segment2.y+=vy;
        }
         
        private function checkFloor(seg:Segment):void {
            var yMax:Number=seg.getBounds(this).bottom;
            //如果最下面的小腿超出了舞台下边界
            if (yMax>stage.stageHeight) {
                var dy:Number=yMax-stage.stageHeight;
                //将所有的关节(大腿和小腿)全部上移，以防止两条腿超出舞台下边界
                segment0.y-=dy;
                segment1.y-=dy;
                segment2.y-=dy;
                segment3.y-=dy;
                //速度反弹
                vx-=seg.vx;
                vy-=seg.vy;
            }
        }
         
        //屏幕环绕
        private function checkWalls():void {
            var w:Number=stage.stageWidth+200;
            if (segment0.x>stage.stageWidth+100) {
                segment0.x-=w;
                segment1.x-=w;
                segment2.x-=w;
                segment3.x-=w;
            } else if (segment0.x < 100*-1) {
                segment0.x+=w;
                segment1.x+=w;
                segment2.x+=w;
                segment3.x+=w;
            }
        }
    }
}