Flex高级动画教程中所讲的寻找行为

----向量类

package vector.steering?

{

??? import flash.display.Graphics;

???

??? /**

??? ?* ...

??? ?* @author DefaultUser (Tools -> Custom Arguments...)

??? ?*/

??? public class Vector2D

??? {

??????? private var _x:Number;

??????? private var _y:Number;

???????

??????? public function Vector2D(x:Number=0,y:Number=0)

??????? {

??????????? _x = x;

??????????? _y = y;

??????? }

???????

??????? public function draw(graphics:Graphics,color:uint=0):void {

??????????? graphics.lineStyle(0,color);

??????????? graphics.moveTo(0,0);

??????????? graphics.lineTo(_x,_y);

??????? }

??????? /**

??????? ?* 返回自己的克隆向量

??????? ?* @return Vector2D

??????? ?*/

??????? public function clone():Vector2D {

??????????? return new Vector2D(_x,_y);

??????? }

??????? /**

??????? ?* 返回 Vector2D (0,0)

??????? ?* @return Vector2D

??????? ?*/

??????? public function zero():Vector2D {

??????????? _x = 0;

??????????? _y = 0;

??????????? return this;

??????? }

??????? /**

??????? ?* 返回是否为零向量

??????? ?* @return Boolean

??????? ?*/

??????? public function iszero():Boolean {

??????????? return _x == 0 && _y == 0;

??????? }

??????? public function set length(value:Number):void {

??????????? var a:Number = angle;

??????????? _x = Math.cos(a) * value;

??????????? _y = Math.sin(a) * value;

??????? }

??????? /**

??????? ?* 返回向量的长度

??????? ?*/

??????? public function get length():Number {

??????????? return Math.sqrt(lengthSQ);

??????? }

??????? public function get lengthSQ():Number {

??????????? return _x * _x + _y * _y;

??????? }

??????? public function set angle(value:Number):void {

??????????? var len:Number = value;

??????????? _x = Math.cos(value) * len;

??????????? _y = Math.sin(value) * len;

??????? }

??????? public function get angle():Number {

??????????? return Math.atan2(_y,_x);

??????? }

??????? /**

??????? ?* 返回垂直向量

??????? ?*/

??????? public function get perp():Vector2D {

??????????? return new Vector2D( -y,x);

??????? }

??????? public function set x(value:Number):void {

??????????? _x = value;

??????? }

??????? public function get x():Number {

??????????? return _x;

??????? }

??????? public function set y(value:Number):void {

??????????? _y = value;

??????? }

??????? public function get y():Number {

??????????? return _y;

??????? }

??????? /**

??????? ?* 向量单位化

??????? ?* @return Vector2D

??????? ?*/

??????? public function normalize():Vector2D {

??????????? if (length == 0) {

??????????????? _x = 1;

??????????????? return this;

??????????? }

??????????? var len:Number = length;

??????????? _x /= len;

??????????? _y /= len;

???????????

??????????? return this;

??????? }

??????? public function scale(value:uint):Vector2D {

???????????

??????????? return new Vector2D(_x * value,_y * value);

??????? }

??????? /**

??????? ?* 限制向量的最大长度

??????? ?* @param?? max

??????? ?* @return Vector2D

??????? ?*/

??????? public function truncate(max:Number):Vector2D {

??????????? length = Math.min(max,length);

??????????? return this;

??????? }

??????? /**

??????? ?* 向量反转

??????? ?* @return Vector2D

??????? ?*/

??????? public function reverse():Vector2D {

??????????? _x = -_x;

??????????? _y = -_y;

???????????

??????????? return this;

??????? }

??????? /**

??????? ?* 返回是否为单位向量

??????? ?* @return Boolean

??????? ?*/

??????? public function isNormalized():Boolean {

??????????? return length == 1.0;

??????? }

??????? public function dotProd(v2:Vector2D):Number {

??????????? return _x * v2.x + _y * v2.y;

??????? }

??????? public function crossProd(v2:Vector2D):Number {

??????????? return _x * v2.y - _y * v2.x;

??????? }

??????? /**

??????? ?* 返回两个向量的角度

??????? ?* @param?? v1

??????? ?* @param?? v2

??????? ?* @return Number

??????? ?*/

??????? public function angleBetween(v1:Vector2D,v2:Vector2D):Number {

??????????? if (!v1.isNormalized()) v1 = v1.clone().normalize();

??????????? if (!v2.isNormalized()) v2 = v2.clone().normalize();

??????????? return Math.acos(v1.dotProd(v2));

??????? }

??????? /**

??????? ?*

??????? ?* @param?? v2

??????? ?* @return Vector2D

??????? ?*/

??????? public function sign(v2:Vector2D):int {

??????????? return perp.dotProd(v2) < 0? -1:1;

??????? }

??????? /**

??????? ?* 返回两个Vector2D之间的距离

??????? ?* @param?? v2

??????? ?* @return Number

??????? ?*/

??????? public function dist(v2:Vector2D):Number {

??????????? return Math.sqrt(distSQ(v2));

??????? }

??????? /**

??????? ?* 返回向量的平方值

??????? ?* @param?? v2

??????? ?* @return Number

??????? ?*/

??????? public function distSQ(v2:Vector2D):Number {

??????????? var dx:Number = v2.x - x;

??????????? var dy:Number = v2.y - y;

??????????? return dx * dx + dy * dy;

??????? }

??????? /**

??????? ?* 加上向量v2

??????? ?* @param?? v2

??????? ?* @return Vector2D

??????? ?*/

??????? public function add(v2:Vector2D):Vector2D {

??????????? return new Vector2D(_x + v2.x,_y + v2.y);

??????? }

??????? /**

??????? ?* 减去向量v2

??????? ?* @param?? v2

??????? ?* @return Vector2D

??????? ?*/

??????? public function substract(v2:Vector2D):Vector2D {

??????????? return new Vector2D(_x - v2.x,_y - v2.y);

??????? }

??????? /**

??????? ?* 乘以向量value

??????? ?* @param?? value

??????? ?* @return Vector2D

??????? ?*/

??????? public function multiply(value:Number):Vector2D {

??????????? return new Vector2D(_x * value,_y * value);

??????? }

??????? /**

??????? ?* 除以向量value

??????? ?* @param?? value

??????? ?* @return Vector2D

??????? ?*/

??????? public function divide(value:Number):Vector2D {

??????????? return new Vector2D(_x/value,_y/value);

??????? }

??????? /**

??????? ?* 判断两个向量是否相同

??????? ?* @param?? v2

??????? ?* @return

??????? ?*/

??????? public function equals(v2:Vector2D):Boolean {

??????????? return _x == v2.x && _y == v2.y;

??????? }

??????? public function toString():String {

??????????? return "[Vector2D(x:" + _x + ",y:" + _y + ")]";

??????? }

??? }

}

?

----vehicle基类

package vector.steering

{

??? import flash.display.Sprite;

???

??? public class Vehicle extends Sprite

??? {

??????? protected var _edgeBehavior:String = WRAP;

??????? protected var _mass:Number = 1.0; //质量

??????? protected var _maxSpeed:Number = 10;

??????? protected var _position:Vector2D; //位置向量

??????? protected var _velocity:Vector2D; //速度向量

???????

??????? public static const WRAP:String = "wrap";

??????? public static const BOUNCE:String = "boounce";

???????

??????? public function Vehicle(){

??????????? _position = new Vector2D();

??????????? _velocity = new Vector2D();

??????????? draw();

??????? }

???????

??????? protected function draw():void{

??????????? graphics.clear();

??????????? graphics.lineStyle(0);

??????????? graphics.moveTo(10,0);

??????????? graphics.lineTo(-10,5);

??????????? graphics.lineTo(-10,-5);

??????????? graphics.lineTo(10,0);

??????? }

???????

??????? public function update():void{

??????????? _velocity.truncate(_maxSpeed);? //限制最大速度

??????????? _position = _position.add(_velocity);?? //添加速度向量

???????????

??????????? if(_edgeBehavior == WRAP){

??????????????? wrap();

??????????? }else if(_edgeBehavior == BOUNCE){

??????????????? bounce();

??????????? }

???????????

??????????? //更新机车类坐标

??????????? x = position.x;

??????????? y = position.y;

???????????

??????????? //更新转向速度

??????????? rotation = _velocity.angle * 180/Math.PI;

??????? }

???????

??????? /**

??????? ?* 碰到墙壁，反弹

??????? ?* 直接更改相反方向的向量坐标

??????? ?*/

??????? public function bounce():void{

??????????? if(stage != null){

??????????????? if(position.x > stage.stageWidth){

??????????????????? position.x = stage.stageWidth;

??????????????????? velocity.x *= -1;

??????????????? }else if(position.x < 0){

??????????????????? position.x = 0;

??????????????????? velocity.x *= -1;

??????????????? }

???????????????

??????????????? if(position.y > stage.stageHeight){

??????????????????? position.y = stage.stageHeight;????????

??????????????????? velocity.y *= -1;

??????????????? } else if(position.y < 0) {

??????????????????? position.y = 0;

??????????????????? velocity.y *= -1;

??????????????? }

??????????? }

??????? }

???????

??????? public function wrap():void{

??????????? if(stage != null){

??????????????? if(position.x > stage.stageWidth) position.x = 0;

??????????????? if(position.x < 0) position.x = stage.stageWidth;

??????????????? if(position.y > stage.stageHeight) position.y = 0;

??????????????? if(position.y < 0) position.y = stage.stageHeight;

??????????? }

??????? }

???????

???????

??????? public function set edgeBehavior(value:String):void{

??????????? _edgeBehavior = value;

??????? }

???????

??????? public function get edgeBehavior():String{

??????????? return _edgeBehavior;

??????? }

???????

??????? public function set mass(value:Number):void{

??????????? _mass = value;

??????? }

???????

??????? public function get mass():Number{

??????????? return _mass;

??????? }

???????

??????? public function set maxSpeed(value:Number):void{

??????????? _maxSpeed = value;

??????? }

???????

??????? public function get maxSpeed():Number{

??????????? return _maxSpeed;

??????? }

???????

??????? public function set position(value:Vector2D):void{

??????????? _position = value;

??????????? x = _position.x;

??????????? y = _position.y;

??????? }

???????

??????? public function get position():Vector2D{

??????????? return _position;

??????? }

???????

??????? public function set velocity(value:Vector2D):void{

??????????? _velocity = value;

??????? }

???????

??????? public function get velocity():Vector2D{

??????????? return _velocity;

??????? }

???????

??????? override public function set x(value:Number):void{

??????????? super.x = value;

??????????? _position.x = x;

??????? }

???????

??????? override public function set y(value:Number):void{

??????????? super.y = value;

??????????? _position.y = y;

??????? }

??? }

}

?

----SteeredVehicle机车子类

package vector.steering

{

??? public class SteeredVehicle extends Vehicle

??? {

??????? private var _maxForce:Number = 1;????? //旋转力

??????? private var _steeringForce:Vector2D; //作为叠加后的转向合力

???????

??????? public function SteeredVehicle()

??????? {

??????????? _steeringForce = new Vector2D();

??????????? super();

??????? }

???????

??????? public function set maxForce(value:Number):void{

??????????? _maxForce = value;

??????? }

???????

??????? public function get maxForce():Number{

??????????? return _maxForce;

??????? }

??????? /**

??????? ?* 主要控制旋转力

??????? ?*/

??????? override public function update():void{

??????????? _steeringForce.truncate(_maxForce);

??????????? _steeringForce = _steeringForce.divide(_mass);

??????????? _velocity = _velocity.add(_steeringForce);

??????????? _steeringForce = new Vector2D();

??????????? super.update();

??????? }

???????

??????? /**

??????? ?* 寻找行为 把机车移动到指定点

??????? ?*/

??????? public function seek(target:Vector2D):void{

??????????? var desiredVelocity:Vector2D = target.substract(_position);

??????????? desiredVelocity.normalize();

??????????? desiredVelocity = desiredVelocity.multiply(_maxSpeed);

??????????? var force:Vector2D = desiredVelocity.substract(_velocity);

??????????? _steeringForce = _steeringForce.add(force);

???????????

??????? }

??? }

}

?

---测试类

package vector.chapter1

{

??? import flash.display.Sprite;

??? import flash.display.StageAlign;

??? import flash.display.StageScaleMode;

??? import flash.events.Event;

???

??? import vector.steering.SteeredVehicle;

??? import vector.steering.Vector2D;

???

??? public class SeekTest extends Sprite

??? {

??????? private var _vehicle:SteeredVehicle;

???????

??????? public function SeekTest()

??????? {

??????????? stage.align = StageAlign.TOP_LEFT;

??????????? stage.scaleMode = StageScaleMode.NO_SCALE;

???????????

??????????? _vehicle = new SteeredVehicle();

??????????? addChild(_vehicle);

???????????

??????????? addEventListener(Event.ENTER_FRAME,onEnterFrame);

??????? }

???????

??????? private function onEnterFrame(event:Event):void{

??????????? _vehicle.seek(new Vector2D(mouseX,mouseY));

??????????? _vehicle.update();

??????? }

??? }

}