as3绳子的算法.doc

package import flash.display.Shape;import flash.display.Sprite;import flash.events.Event;/* * . * author Maxim Sprey */public class stick extends Sprite / Stick propertiesvar mass:Number = 6;/总质量var len:Number = 3;/总长度var div:Number = 50;var massDiv:Number = mass / div;/每一节的质量var lenDiv:Number = len / div;/每一节的长度0.06米 / Circle propertiesvar cX:Number = 300;var cY:Number = 200;var cR:Number = 50;/ World Characteristicsvar g:Number = 9.81;/重力加速度var pm:Number = 100; / Pixels/meter/像素相对 米的长度比例总长度为3米 有50节 那么每节相当于1.5个像素var dt:Number = 1 / 60;/时间单位帧频为60的画 dt 相当于一帧的时间 这是时间单位/var itr:uint = 3; / Number of rigid body iterations/ Program Characteristicsvar pX:Array = ;var pY:Array = ;var oX:Array = ;var oY:Array = ;var aX:Array = ;var aY:Array = ;var mS:Shape = new Shape();/每一个点的形状 我在这里 只是当他为一个空点 然后每2个点之间用直线连接public function stick():void /初始化 速度 加速度 位移for (var i:uint = 0; i = div; i+) / 初始化运动后坐标pXi = 10 + (lenDiv * pm * i);pYi = 10;/初始化运动前的坐标oXi = 10 + (lenDiv * pm * i);oYi = 10;/初始化加速度aXi = 0;aYi = 0;addChild(mS);addEventListener(Event.ENTER_FRAME, frame);public function frame(evt:Event):void /固定开始点pX0 =300 ;pY0 = 200;/最后一个点跟随鼠标运动pXpX.length - 1 = stage.mouseX;pYpY.length - 1 = stage.mouseY;/设置重力加速度accForces(); verlet();/判断是否碰到圆 然后做什么处理/checkColl();for (var j:uint = 0; j = div-1;j+)satConstraints();/ Draw linemS.graphics.clear();mS.graphics.lineStyle(1, 0x000000, 2);mS.graphics.moveTo(0,0);mS.graphics.drawCircle(cX, cY, cR);mS.graphics.moveTo(0, 0);mS.graphics.moveTo(pX0, pY0);pX0 =300 ;pY0 = 200;pXpX.length - 1 = stage.mouseX;pYpY.length - 1 = stage.mouseY;/画圆或者 矩形for (var i:uint = 0; i = div; i+) mS.graphics.lineTo(pXi, pYi);/mS.graphics.drawRect(pXi, pYi, 0,0);public function verlet():void for (var i:uint = 0; i = div; i+) var tempX:Number = pXi;pXi += (0.99*pXi - 0.99*oXi) + (aXi * pm * dt * dt);var tempY:Number = pYi;pYi += (0.99*pYi - 0.99*oYi) + (aYi * pm * dt * dt);oXi = tempX;oYi = tempY;public function accForces():void for (var i:uint = 1; i = div; i+) aYi = g;public function satConstraints():void for (var i:uint = 1; i = div; i+) var dx:Number = (pXi - pXi - 1) / pm;var dy:Number = (pYi - pYi - 1) / pm;var d:Number = Math.sqrt(dx * dx) + (dy * dy);var diff:Number = d - lenDiv;pXi -= (dx / d) * 0.5 *pm* diff;pYi -= (dy / d) * 0.5 *pm* diff;pXi - 1 += (dx / d) * 0.5 *pm* diff;pYi - 1 += (dy / d) * 0.5 *pm* diff;public function checkColl():void for (var i:uint = 0; i = div; i+) var dx:Number = pXi - cX;var dy:Number = pYi - cY;var r:Number =