Flash/Flex学习笔记(49)：3D基础
之前我们所做的动画都是基于x,y二维坐标轴的，在三维动画中我们还需要增加一个垂直于屏幕“向里”或“向外”的Z轴，那么z轴到底是应该向外，还是向里呢?这个其实无所谓，不过为了统一，习惯上通常把z轴约定为向里，即所谓的“右手坐标系”
右手坐标系的得名：伸出右手，让食指、中指、大拇指相互垂直；然后 食指指向x轴正向，中指指向y轴正向，则大拇指所指方向即为z轴正向。(事实上这个姿势酷似周杰伦周董的招牌动作)
三维透视的基本规则：
物体在Z轴上的坐标越大(越远)，则看起来越小(将上图坐标系旋转，把z轴转到x轴方向后，得到下图)，如果距离足够远，则物体将消失于屏幕上的某个特定点(通常称为“消失点”)
技术上的主要处理：动态调整物体的scaleX与scaleY（同时因为物体的大小改变后，相应的x,y坐标值通常也会改变，所以x,y坐标也要做相应调整以符合透视规则），基本公式如下：
scale = fl/(fl+z)
var ball:Ball = new Ball();
addChild(ball);
//观察点 相对于 消失点的坐标
var xPos:Number=0;
var yPos:Number=0;
var zPos:Number=0;
var fl:Number=250;//焦距
//消失点
var vpX:Number=stage.stageWidth/2;
var vpY:Number=stage.stageHeight/2;
addEventListener(Event.ENTER_FRAME, EnterFrameHandler);
stage.addEventListener(KeyboardEvent.KEY_DOWN, KeyDownHandler);
stage.addEventListener(MouseEvent.MOUSE_WHEEL,MouseWheelHandler);
//鼠标滚轮事件(注：必须让stage获取焦点时-即用鼠标在动画上点击一下，该事件才会触发，另外还要注意：嵌入网页时，浏览器也会响应鼠标滚轮)
function MouseWheelHandler(e:MouseEvent):void {
zPos += (e.delta*5);
}
function EnterFrameHandler(event:Event):void {
if (zPos> -fl) {
ball.visible=true;
xPos=mouseX-vpX;
yPos=mouseY-vpY;
var scale:Number = fl / (fl + zPos);
ball.scaleX=ball.scaleY=scale;
ball.x=vpX+xPos*scale;
ball.y=vpY+yPos*scale;
} else {
ball.visible=false;
}
//辅助线
graphics.clear();
graphics.lineStyle(1,0xcccccc);
graphics.moveTo(vpX,vpY);
graphics.lineTo(vpX,ball.y);
graphics.moveTo(vpX,vpY);
graphics.lineTo(ball.x,vpY);
graphics.lineStyle(1,0x0000ff,0.5);
graphics.moveTo(vpX,vpY);
graphics.lineTo(ball.x,ball.y);
graphics.lineStyle(1,0xff0000,0.5);
graphics.moveTo(ball.x,ball.y);
graphics.lineTo(mouseX,mouseY);
}
//键盘事件
function KeyDownHandler(e:KeyboardEvent):void {
if (e.keyCode==Keyboard.UP) {
zPos+=5;
} else if (e.keyCode == Keyboard.DOWN) {
zPos-=5;
}
}这个示例中，"鼠标所在位置"充当了"观察点"(即前面示意图中的"人眼"位置)，电脑屏幕所在平面即物体的成像面，用键盘上下键可调整小球在Z轴上的位置，然后移动鼠标位置，通过辅助线观察变化。
基本的3D运动：
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.events.KeyboardEvent;
import flash.ui.Keyboard;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
public class Velocity3D extends Sprite {
private var ball:Ball;
//相当于消失点的坐标
private var xpos:Number=0;
private var ypos:Number=0;
private var zpos:Number=0;
//x,y,z三轴上的速度分量
private var vx:Number=0;
private var vy:Number=0;
private var vz:Number=0;
private var friction:Number=0.98;
private var fl:Number=250;
//消失点
private var vpX:Number=stage.stageWidth/2;
private var vpY:Number=stage.stageHeight/2;
public function Velocity3D() {
init();
}
private function init():void {
stage.align = StageAlign.TOP_LEFT;
stage.scaleMode = StageScaleMode.NO_SCALE;
ball = new Ball(20);
addChild(ball);
addEventListener(Event.ENTER_FRAME, EnterFrameHandler);
stage.addEventListener(KeyboardEvent.KEY_DOWN, KeyDownHandler);
}
private function EnterFrameHandler(event:Event):void {
vpX =stage.stageWidth/2;
vpY =stage.stageHeight/2;
xpos+=vx;
ypos+=vy;
zpos+=vz;
vx*=friction;
vy*=friction;
vz*=friction;
if (zpos>-fl) {
var scale:Number = fl / (fl + zpos);
ball.scaleX=ball.scaleY=scale;
ball.x=vpX+xpos*scale;
ball.y=vpY+ypos*scale;
ball.visible=true;
} else {
ball.visible=false;
}
//辅助线
graphics.clear();
graphics.lineStyle(1,0xefefef);
graphics.moveTo(0,stage.stageHeight/2);
graphics.lineTo(stage.stageWidth,stage.stageHeight/2);
graphics.lineTo(stage.stageWidth-15,stage.stageHeight/2-8);
graphics.moveTo(stage.stageWidth,stage.stageHeight/2);
graphics.lineTo(stage.stageWidth-15,stage.stageHeight/2+8);
graphics.moveTo(stage.stageWidth/2,0);
graphics.lineTo(stage.stageWidth/2,stage.stageHeight);
graphics.lineTo(stage.stageWidth/2-8,stage.stageHeight-15);
graphics.moveTo(stage.stageWidth/2,stage.stageHeight);
graphics.lineTo(stage.stageWidth/2+8,stage.stageHeight-15);
graphics.lineStyle(1,0xdadada);
graphics.moveTo(vpX,vpY);
graphics.lineTo(ball.x,ball.y);
}
private function KeyDownHandler(e:KeyboardEvent):void {
switch (e.keyCode) {
case Keyboard.UP :
vy-=1;
break;
case Keyboard.DOWN :
vy+=1;
break;
case Keyboard.LEFT :
vx-=1;
break;
case Keyboard.RIGHT :
vx+=1;
break;
case Keyboard.SHIFT :
vz+=0.5;
break;
case Keyboard.CONTROL :
vz-=0.5;
break;
default :
break;
}
}
}
}上下左右键控制x,y轴方向速度，shift/ctrl键控制z轴速度(当然这个示例还没考虑到3D环境中的边界反弹,下面就要谈到这个问题)
3维运动反弹：
这个需要一点想象力，二维情况下，通常只要把舞台的四个边当作边界就足够了，但是试想一下：在一个立体的空间里，要限制一个物体的活动范围，得要有6个边界面(上，下，左，右，前，后)
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
public class Bounce3D extends Sprite {
private var ball:Ball;
private var xpos:Number=0;
private var ypos:Number=0;
private var zpos:Number=0;
private var vx:Number=Math.random()*12-6;
private var vy:Number=Math.random()*12-6;
private var vz:Number=Math.random()*12-6;
private var fl:Number=250;
//消失点
private var vpX:Number=stage.stageWidth/2;
private var vpY:Number=stage.stageHeight/2;
//相对于消失点的六个边界面(上，下，左，右，前，后)
private var top:Number=-100;
private var bottom:Number=100;
private var left:Number=-100;
private var right:Number=100;
private var front:Number=100;
private var back:Number=-100;
public function Bounce3D() {
init();
}
private function init():void {
stage.align = StageAlign.TOP_LEFT;
stage.scaleMode = StageScaleMode.NO_SCALE;
ball=new Ball(15);
addChild(ball);
addEventListener(Event.ENTER_FRAME, EnterFrameHandler);
}
private function EnterFrameHandler(event:Event):void {
vpX =stage.stageWidth/2;
vpY =stage.stageHeight/2;
xpos+=vx;
ypos+=vy;
zpos+=vz;
var radius:Number=ball.radius;
//左右边界
if (xpos+radius>right) {
xpos=right-radius;
vx*=-1;
} else if (xpos - radius < left) {
xpos=left+radius;
vx*=-1;
}
//上下边界
if (ypos+radius>bottom) {
ypos=bottom-radius;
vy*=-1;
} else if (ypos - radius < top) {
ypos=top+radius;
vy*=-1;
}
//前后边界
if (zpos+radius>front) {
zpos=front-radius;
vz*=-1;
} else if (zpos - radius < back) {
zpos=back+radius;
vz*=-1;
}
//换算成平面二维坐标及缩放比率
if (zpos>- fl) {
var scale:Number = fl / (fl + zpos);
ball.scaleX=ball.scaleY=scale;
ball.x=vpX+xpos*scale;
ball.y=vpY+ypos*scale;
ball.visible=true;
} else {
ball.visible=false;
}
//辅助线
graphics.clear();
graphics.lineStyle(1,0xccccff);
graphics.moveTo(0,stage.stageHeight/2);
graphics.lineTo(stage.stageWidth,stage.stageHeight/2);
graphics.lineTo(stage.stageWidth-15,stage.stageHeight/2-8);
graphics.moveTo(stage.stageWidth,stage.stageHeight/2);
graphics.lineTo(stage.stageWidth-15,stage.stageHeight/2+8);
graphics.moveTo(0,stage.stageHeight);
graphics.lineTo(stage.stageWidth,0);
graphics.lineTo(stage.stageWidth-15,2);
graphics.moveTo(stage.stageWidth,0);
graphics.lineTo(stage.stageWidth-6,13);
graphics.moveTo(stage.stageWidth/2,0);
graphics.lineTo(stage.stageWidth/2,stage.stageHeight);
graphics.lineTo(stage.stageWidth/2-8,stage.stageHeight-15);
graphics.moveTo(stage.stageWidth/2,stage.stageHeight);
graphics.lineTo(stage.stageWidth/2+8,stage.stageHeight-15);
graphics.lineStyle(1,0xffccff);
graphics.moveTo(vpX,vpY);
graphics.lineTo(ball.x,ball.y);
}
}
}也许这样看得并不清楚，再加入更多的小球反弹，可能更容易理解一些，不过为了方便代码处理，先定义一个新的小球类:Ball3D
package {
import flash.display.Sprite;
public class Ball3D extends Sprite {
public var radius:Number;
private var color:uint;
public var xpos:Number=0;
public var ypos:Number=0;
public var zpos:Number=0;
public var vx:Number=0;
public var vy:Number=0;
public var vz:Number=0;
public var mass:Number=1;
public function Ball3D(radius:Number=40, color:uint=0xff0000) {
this.radius=radius;
this.color=color;
init();
}
public function init():void {
graphics.lineStyle(0);
graphics.beginFill(color);
graphics.drawCircle(0, 0, radius);
graphics.endFill();
}
}
}多个小球的3D反弹:
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
public class MultiBounce3D extends Sprite {
private var balls:Array;
private var numBalls:uint=20;
private var fl:Number=250;
private var vpX:Number=stage.stageWidth/2;
private var vpY:Number=stage.stageHeight/2;
private var top:Number=-120;
private var bottom:Number=120;
private var left:Number=-120;
private var right:Number=120;
private var front:Number=120;
private var back:Number=-120;
public function MultiBounce3D() {
init();
}
private function init():void {
stage.align = StageAlign.TOP_LEFT;
stage.scaleMode = StageScaleMode.NO_SCALE;
balls = new Array();
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=new Ball3D(15,Math.random()*0xffffff);
balls.push(ball);
ball.vx=Math.random()*10-5;
ball.vy=Math.random()*10-5;
ball.vz=Math.random()*10-5;
addChild(ball);
}
addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
private function onEnterFrame(event:Event):void {
vpX =stage.stageWidth/2;
vpY =stage.stageHeight/2;
graphics.clear();
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=balls[i];
move(ball);
}
}
private function move(ball:Ball3D):void {
var radius:Number=ball.radius;
ball.xpos+=ball.vx;
ball.ypos+=ball.vy;
ball.zpos+=ball.vz;
//6边界检测
if (ball.xpos+radius>right) {
ball.xpos=right-radius;
ball.vx*=-1;
} else if (ball.xpos - radius < left) {
ball.xpos=left+radius;
ball.vx*=-1;
}
if (ball.ypos+radius>bottom) {
ball.ypos=bottom-radius;
ball.vy*=-1;
} else if (ball.ypos - radius < top) {
ball.ypos=top+radius;
ball.vy*=-1;
}
if (ball.zpos+radius>front) {
ball.zpos=front-radius;
ball.vz*=-1;
} else if (ball.zpos - radius < back) {
ball.zpos=back+radius;
ball.vz*=-1;
}
//转换化2D坐标
if (ball.zpos>- fl) {
var scale:Number = fl / (fl + ball.zpos);
ball.scaleX=ball.scaleY=scale;
ball.x=vpX+ball.xpos*scale;
ball.y=vpY+ball.ypos*scale;
ball.visible=true;
} else {
ball.visible=false;
}
//辅助线
graphics.lineStyle(1,0xccccff);
graphics.moveTo(0,stage.stageHeight/2);
graphics.lineTo(stage.stageWidth,stage.stageHeight/2);
graphics.lineTo(stage.stageWidth-15,stage.stageHeight/2-8);
graphics.moveTo(stage.stageWidth,stage.stageHeight/2);
graphics.lineTo(stage.stageWidth-15,stage.stageHeight/2+8);
graphics.moveTo(0,stage.stageHeight);
graphics.lineTo(stage.stageWidth,0);
graphics.lineTo(stage.stageWidth-15,2);
graphics.moveTo(stage.stageWidth,0);
graphics.lineTo(stage.stageWidth-6,13);
graphics.moveTo(stage.stageWidth/2,0);
graphics.lineTo(stage.stageWidth/2,stage.stageHeight);
graphics.lineTo(stage.stageWidth/2-8,stage.stageHeight-15);
graphics.moveTo(stage.stageWidth/2,stage.stageHeight);
graphics.lineTo(stage.stageWidth/2+8,stage.stageHeight-15);
graphics.lineStyle(1,0xff99ff);
graphics.moveTo(vpX,vpY);
graphics.lineTo(ball.x,ball.y);
}
}
}仔细观察一下，相信不少人会发现问题：物体的前后顺序不对，远处的物体居然挡住了近处的物体。(css中可以通过z-Index来调整，silverlight的canvas中也有类似的zIndex，但在As3中如何做呢?)
先跑一下题，来看一个小技巧：Object 数组的排序
var arrTest = [{age:20,name:"a"},{age:50,name:"b"},{age:30,name:"c"}]
arrTest.sortOn("age",Array.DESCENDING);//按age值倒排
for(var i:int=0,j=arrTest.length;i<j;i++){
trace(arrTest[i].age ,arrTest[i].name);
}是不是很好用！
ok，问题解决了：Flash的显示列表中，最后被addChild的物体总是显示在上面，在Flash内部"舞台上的每个物体"都对应一个索引值，随着物体不断被添加到舞台上，其对应的索引值也不断增加，我们可以通过调整索引值来改变物体的显示顺序.
基本测试：
var ballA = new Ball(50);
ballA.x = stage.stageWidth/2;
ballA.y = stage.stageHeight/2;
addChild(ballA);
var ballB = new Ball(45,0x0000ff);
ballB.x = ballA.x;
ballB.y = ballA.y + 20;
addChild(ballB);
btn1.addEventListener(MouseEvent.MOUSE_DOWN,btn1Click);
function btn1Click(e:MouseEvent):void{
setChildIndex(ballB,0);
setChildIndex(ballA,1);
}
btn2.addEventListener(MouseEvent.MOUSE_DOWN,btn2Click);
function btn2Click(e:MouseEvent):void{
setChildIndex(ballB,1);
setChildIndex(ballA,0);
}调整后的3D反弹
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
public class MultiBounce3D extends Sprite {
private var balls:Array;
private var numBalls:uint=20;
private var fl:Number=250;
private var vpX:Number=stage.stageWidth/2;
private var vpY:Number=stage.stageHeight/2;
private var top:Number=-120;
private var bottom:Number=120;
private var left:Number=-120;
private var right:Number=120;
private var front:Number=120;
private var back:Number=-120;
public function MultiBounce3D() {
init();
}
private function init():void {
stage.align=StageAlign.TOP_LEFT;
stage.scaleMode=StageScaleMode.NO_SCALE;
balls = new Array();
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=new Ball3D(15,Math.random()*0xffffff);
balls.push(ball);
ball.vx=Math.random()*10-5;
ball.vy=Math.random()*10-5;
ball.vz=Math.random()*10-5;
addChild(ball);
}
addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
private function onEnterFrame(event:Event):void {
vpX=stage.stageWidth/2;
vpY=stage.stageHeight/2;
graphics.clear();
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=balls[i];
move(ball);
}
sortZ();
}
function sortZ():void {
balls.sortOn("zpos", Array.DESCENDING | Array.NUMERIC);
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=balls[i];
setChildIndex(ball, i);
}
}
private function move(ball:Ball3D):void {
var radius:Number=ball.radius;
ball.xpos+=ball.vx;
ball.ypos+=ball.vy;
ball.zpos+=ball.vz;
//6边界检测
if (ball.xpos+radius>right) {
ball.xpos=right-radius;
ball.vx*=-1;
} else if (ball.xpos - radius < left) {
ball.xpos=left+radius;
ball.vx*=-1;
}
if (ball.ypos+radius>bottom) {
ball.ypos=bottom-radius;
ball.vy*=-1;
} else if (ball.ypos - radius < top) {
ball.ypos=top+radius;
ball.vy*=-1;
}
if (ball.zpos+radius>front) {
ball.zpos=front-radius;
ball.vz*=-1;
} else if (ball.zpos - radius < back) {
ball.zpos=back+radius;
ball.vz*=-1;
}
//转换化2D坐标
if (ball.zpos>- fl) {
var scale:Number = fl / (fl + ball.zpos);
ball.scaleX=ball.scaleY=scale;
ball.x=vpX+ball.xpos*scale;
ball.y=vpY+ball.ypos*scale;
ball.visible=true;
} else {
ball.visible=false;
}
//辅助线
graphics.lineStyle(1,0xccccff);
graphics.moveTo(0,stage.stageHeight/2);
graphics.lineTo(stage.stageWidth,stage.stageHeight/2);
graphics.lineTo(stage.stageWidth-15,stage.stageHeight/2-8);
graphics.moveTo(stage.stageWidth,stage.stageHeight/2);
graphics.lineTo(stage.stageWidth-15,stage.stageHeight/2+8);
graphics.moveTo(0,stage.stageHeight);
graphics.lineTo(stage.stageWidth,0);
graphics.lineTo(stage.stageWidth-15,2);
graphics.moveTo(stage.stageWidth,0);
graphics.lineTo(stage.stageWidth-6,13);
graphics.moveTo(stage.stageWidth/2,0);
graphics.lineTo(stage.stageWidth/2,stage.stageHeight);
graphics.lineTo(stage.stageWidth/2-8,stage.stageHeight-15);
graphics.moveTo(stage.stageWidth/2,stage.stageHeight);
graphics.lineTo(stage.stageWidth/2+8,stage.stageHeight-15);
graphics.lineStyle(1,0xff99ff);
graphics.moveTo(vpX,vpY);
graphics.lineTo(ball.x,ball.y);
}
}
}3D粒子喷射:
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
//设置动画背景为黑色
[SWF(backgroundColor=0x000000)]//c#中的特性? 哈
public class Fireworks extends Sprite {
private var balls:Array;
private var numBalls:uint=100;
private var fl:Number=250;
//消失点
private var vpX:Number=stage.stageWidth/2;
private var vpY:Number=stage.stageHeight/2;
private var gravity:Number=0.2;
private var floor:Number=50;//y轴反弹的边界(相对消失点而言)
private var bounce:Number=-0.6;
public function Fireworks() {
init();
}
private function init():void {
stage.scaleMode = StageScaleMode.NO_SCALE;
stage.align = StageAlign.TOP_LEFT;
balls = new Array();
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=new Ball3D(5,Math.random()*0xffffff);
balls.push(ball);
addChild(ball);
}
initVelocity();
addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
private function initVelocity():void{
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=balls[i];
reset(ball);
}
}
private function reset(b:Ball3D):void{
b.ypos=-250;
b.zpos=200;
b.xpos=0;
b.vx=(Math.random()*2-1)*3 //x轴方向速度为-3到+3的随机值(即:看起来有的球向左，有的球向右，在横向扩散)
b.vy=(Math.random()-1)*4; //y轴方向为-4到0之间的随机值(即向下掉)
b.vz=(Math.random()-1)*3; //z轴方向速度为-3到0的随机值(即：所有球从远处向近处喷)
}
private function onEnterFrame(event:Event):void {
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=balls[i];
move(ball);
}
sortZ();
}
private function move(ball:Ball3D):void {
ball.vy+=gravity;
ball.xpos+=ball.vx;
ball.ypos+=ball.vy;
ball.zpos+=ball.vz;
if (ball.ypos>floor) {
ball.ypos=floor;
ball.vy*=bounce;
}
if (ball.zpos>-fl) {
var scale:Number = fl / (fl + ball.zpos);
ball.scaleX=ball.scaleY=scale;
ball.x=vpX+ball.xpos*scale;
ball.y=vpY+ball.ypos*scale;
ball.alpha = scale;//越远的物体，越淡
if (ball.x<0 || ball.x>stage.stageWidth || ball.y>stage.stageHeight || ball.alpha<0.05){
reset(ball);
}
ball.visible=true;
} else {
ball.visible=false;
reset(ball);
}
}
private function sortZ():void {
balls.sortOn("zpos", Array.DESCENDING | Array.NUMERIC);
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=balls[i];
setChildIndex(ball, i);
}
}
}
}Z轴上的屏幕环绕：
类似2d中的处理，当物体在z轴的坐标达到某一限定值时，重新将其设置为相反值，通俗点讲：物体太远(接近看不见时)，重新将其放在无限近的地方(通常是观察者背后)，物体太近（甚至跑到观察者背后时），重新将其放在无限远处.
var trees:Array;
var numTrees:uint=100;
var fl:Number=250;
var vpX:Number=stage.stageWidth/2;
var vpY:Number=stage.stageHeight/2;
var floor:Number=50;
var vz:Number=0;
var friction:Number=0.98;
var temp:Number=0;
function init():void {
trees = new Array();
for (var i:uint = 0; i < numTrees; i++) {
var tree:Tree = new Tree();
trees.push(tree);
tree.xpos=Math.random()*2000-1000;
tree.ypos=floor;
tree.zpos=Math.random()*10000;
addChild(tree);
}
addEventListener(Event.ENTER_FRAME, EnterFrameHandler);
stage.addEventListener(KeyboardEvent.KEY_DOWN, KeyDownHandler);
}
function EnterFrameHandler(event:Event):void {
for (var i:uint = 0; i < numTrees; i++) {
var tree:Tree=trees[i];
move(tree);
}
vz*=friction;
sortZ();
//自动播放的处理
if (temp>500) {
vz-=0.5;
} else {
vz+=0.5;
}
temp++;
if (temp==1000){
temp=0;
}
trace(temp);
}
//按上下键时的速度处理
function KeyDownHandler(event:KeyboardEvent):void {
if (event.keyCode==Keyboard.UP) {
vz-=1;
} else if (event.keyCode == Keyboard.DOWN) {
vz+=1;
}
}
function move(tree:Tree):void {
tree.zpos+=vz;
//如果物体跑到观察点后面了，则重新将其放在无限远处
if (tree.zpos<fl*-1) {
tree.zpos+=10000;
}
//如果物体跑得太远了，重新将其放在观察点身后
if (tree.zpos>10000-fl) {
tree.zpos-=10000;
}
var scale:Number = fl / (fl + tree.zpos);
tree.scaleX=tree.scaleY=scale;
tree.x=vpX+tree.xpos*scale;
tree.y=vpY+tree.ypos*scale;
tree.alpha=scale*0.8+0.2;
}
//z轴排序
function sortZ():void {
trees.sortOn("zpos", Array.DESCENDING | Array.NUMERIC);
for (var i:uint = 0; i < numTrees; i++) {
var tree:Tree=trees[i];
setChildIndex(tree, i);
}
}
init();这个示例中用到了一个新的类Tree，代码如下：
package {
import flash.display.Sprite;
public class Tree extends Sprite {
public var xpos:Number=0;
public var ypos:Number=0;
public var zpos:Number=0;
public function Tree() {
init();
}
public function init():void {
graphics.lineStyle(0,0xffffff);
graphics.lineTo(0,-140-Math.random()*20);
graphics.moveTo(0,-30-Math.random()*30);
graphics.lineTo(Math.random()*80-40,-100-Math.random()*40);
graphics.moveTo(0,-60-Math.random()*40);
graphics.lineTo(Math.random()*60-30,-110-Math.random()*20);
}
}
}上面这个示例的加强版：(左右键控制x轴加速度，上下键控制z轴加速度，空格键整体下落)
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.events.KeyboardEvent;
import flash.ui.Keyboard;
[SWF(backgroundColor=0x000000)]
public class Trees2 extends Sprite {
private var trees:Array;
private var numTrees:uint=100;
private var fl:Number=250;
//消失点
private var vpX:Number=stage.stageWidth/2;
private var vpY:Number=stage.stageHeight/2;
private var floor:Number=50;
//加速度
private var ax:Number=0;
private var ay:Number=0;
private var az:Number=0;
//速度
private var vx:Number=0;
private var vy:Number=0;
private var vz:Number=0;
//重力与摩擦力
private var gravity:Number=0.3;
private var friction:Number=0.98;
public function Trees2() {
init();
}
private function init():void {
trees = new Array();
for (var i:uint = 0; i < numTrees; i++) {
var tree:Tree = new Tree();
trees.push(tree);
tree.xpos=Math.random()*2000-1000;
tree.ypos=floor;
tree.zpos=Math.random()*10000;
addChild(tree);
}
addEventListener(Event.ENTER_FRAME, onEnterFrame);
stage.addEventListener(KeyboardEvent.KEY_DOWN, KeyDownHandler);
stage.addEventListener(KeyboardEvent.KEY_UP, KeyUpHandler);
}
private function onEnterFrame(event:Event):void {
vx+=ax;
vy+=ay;
vz+=az;
vy-=gravity;//负重力？哈，好好理解一下，这一行结合后面的y轴坐标检测，才保证了所有树在空格键松开时，能在y轴方向上恢复原状
for (var i:uint = 0; i < numTrees; i++) {
var tree:Tree=trees[i];
move(tree);
}
vx*=friction;
vy*=friction;
vz*=friction;
sortZ();
}
//键盘按下时，处理加速度
private function KeyDownHandler(event:KeyboardEvent):void {
switch (event.keyCode) {
case Keyboard.UP :
az=-1;
break;
case Keyboard.DOWN :
az=1;
break;
case Keyboard.LEFT :
ax=1;
break;
case Keyboard.RIGHT :
ax=-1;
break;
case Keyboard.SPACE :
ay=1;
break;
default :
break;
}
}
//按键抬起时，加速度置0
private function KeyUpHandler(event:KeyboardEvent):void {
switch (event.keyCode) {
case Keyboard.UP :
case Keyboard.DOWN :
az=0;
break;
case Keyboard.LEFT :
case Keyboard.RIGHT :
ax=0;
break;
case Keyboard.SPACE :
ay=0;
break;
default :
break;
}
}
private function move(tree:Tree):void {
tree.xpos+=vx;
tree.ypos+=vy;
tree.zpos+=vz;
//y轴上的坐标判断，否则所有树将一直向上跑
if (tree.ypos<floor) {
tree.ypos=floor;
}
//z轴屏幕环绕
if (tree.zpos<fl*-1) {
tree.zpos+=10000;
}
if (tree.zpos>10000-fl) {
tree.zpos-=10000;
}
var scale:Number = fl / (fl + tree.zpos);
tree.scaleX=tree.scaleY=scale;
tree.x=vpX+tree.xpos*scale;
tree.y=vpY+tree.ypos*scale;
tree.alpha=scale*0.8 + 0.2;
}
//z轴排序
private function sortZ():void {
trees.sortOn("zpos", Array.DESCENDING | Array.NUMERIC);
for (var i:uint = 0; i < numTrees; i++) {
var tree:Tree=trees[i];
setChildIndex(tree, i);
}
}
}
}3D缓动：
package {
import flash.display.Sprite;
import flash.events.Event;
public class Easing3D extends Sprite {
private var balls:Array;
private var ballNum:Number=20;
private var easing:Number=.1;
private var fl:Number=250;
private var vpX:Number=stage.stageWidth/2;
private var vpY:Number=stage.stageHeight/2;
public function Easing3D() {
init();
}
private function init():void {
balls=new Array(ballNum);
for (var i:int=0; i<ballNum; i++) {
balls[i]=new Ball3D(20,Math.random()*0xffffff);
balls[i].tx=(Math.random()*2-1)*200;
balls[i].ty=(Math.random()*2-1)*200;
balls[i].tz=(Math.random()*2-1)*500;
addChild(balls[i]);
}
addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
private function onEnterFrame(event:Event):void {
for (var i:int=0; i<ballNum; i++) {
move(balls[i]);
}
sortZ();
}
function move(b:Ball3D):void {
var dx:Number=b.tx-b.xpos;
var dy:Number=b.ty-b.ypos;
var dz:Number=b.tz-b.zpos;
//缓动公式
b.xpos+=dx*easing;
b.ypos+=dy*easing;
b.zpos+=dz*easing;
var dist:Number=Math.sqrt(dx*dx+dy*dy+dz*dz);
if (dist<1) {
b.tx=(Math.random()*2-1)*200;
b.ty=(Math.random()*2-1)*200;
b.tz=(Math.random()*2-1)*500;
}
if (b.zpos > -fl) {
var scale:Number = fl / (fl + b.zpos);
b.scaleX=b.scaleY=scale;
b.x=vpX+b.xpos*scale;
b.y=vpY+b.ypos*scale;
b.alpha=scale*0.7+0.3;
b.visible=true;
} else {
b.visible=false;
}
}
//z轴排序
function sortZ():void {
balls.sortOn("zpos", Array.DESCENDING | Array.NUMERIC);
for (var i:uint = 0; i < ballNum; i++) {
var b:Ball3D=balls[i];
setChildIndex(b, i);
}
}
}
}当然这个示例中，要对Ball3D做一些改造：
package {
import flash.display.Sprite;
public class Ball3D extends Sprite {
public var radius:Number;
private var color:uint;
public var xpos:Number=0;
public var ypos:Number=0;
public var zpos:Number=0;
public var vx:Number=0;
public var vy:Number=0;
public var vz:Number=0;
public var tx:Number=0;
public var ty:Number=0;
public var tz:Number=0;
public var mass:Number=1;
public function Ball3D(radius:Number=40, color:uint=0xff0000) {
this.radius=radius;
this.color=color;
init();
}
public function init():void {
graphics.lineStyle(0);
graphics.beginFill(color);
graphics.drawCircle(0, 0, radius);
graphics.endFill();
}
}
}3D弹性运动：
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;
public class Spring3D extends Sprite {
private var balls:Array;
private var ballNum:Number=20;
private var spring:Number=.1;
private var friction:Number=.94;
private var fl:Number=250;
private var vpX:Number=stage.stageWidth/2;
private var vpY:Number=stage.stageHeight/2;
var temp:Number = 0;
public function Spring3D() {
init();
}
private function init():void {
balls=new Array(ballNum);
for (var i:int=0; i<ballNum; i++) {
balls[i]=new Ball3D(20,Math.random()*0xffffff);
balls[i].tx=(Math.random()*2-1)*200;
balls[i].ty=(Math.random()*2-1)*200;
balls[i].tz=(Math.random()*2-1)*300;
addChild(balls[i]);
}
addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
private function onEnterFrame(event:Event):void {
for (var i:int=0; i<ballNum; i++) {
move(balls[i]);
}
sortZ();
temp++;
if (temp>=250){
reset();
temp=0;
}
//trace(temp);
}
function move(b:Ball3D):void {
var dx:Number=b.tx-b.xpos;
var dy:Number=b.ty-b.ypos;
var dz:Number=b.tz-b.zpos;
b.vx+=dx*spring;
b.vy+=dy*spring;
b.vz+=dz*spring;
b.xpos+=b.vx;
b.ypos+=b.vy;
b.zpos+=b.vz;
b.vx*=friction;
b.vy*=friction;
b.vz*=friction;
if (b.zpos>- fl) {
var scale:Number = fl / (fl + b.zpos);
b.scaleX=b.scaleY=scale;
b.x=vpX+b.xpos*scale;
b.y=vpY+b.ypos*scale;
b.alpha=scale*0.8+0.2;
b.visible=true;
} else {
b.visible=false;
}
}
private function reset():void {
for (var i:int=0; i<ballNum; i++) {
balls[i].tx=(Math.random()*2-1)*200;
balls[i].ty=(Math.random()*2-1)*200;
balls[i].tz=(Math.random()*2-1)*300;
}
}
//z轴排序
function sortZ():void {
balls.sortOn("zpos", Array.DESCENDING | Array.NUMERIC);
for (var i:uint = 0; i < ballNum; i++) {
var b:Ball3D=balls[i];
setChildIndex(b, i);
}
}
}
}3D坐标旋转：
其实跟2D坐标旋转几乎完全相同，只不过要指定绕哪个轴旋转
绕z轴旋转
x1 = cos(angleZ) * x - sin(angleZ) * y; y1 = cos(angleZ) * y + sin(angleZ) * x;
绕y轴旋转 x1 = cos(angleY) * x - sin(angleY) * z; z1 = cos(angleY) * z + sin(angleY) * x;
绕x轴旋转 y1 = cos(angleX) * y - sin(angleX) * z; z1 = cos(angleX) * z + sin(angleX) * y;
package {
import flash.display.Sprite;
import flash.events.Event;
public class RotateY extends Sprite {
private var balls:Array;
private var numBalls:uint=50;
private var fl:Number=250;
private var vpX:Number=stage.stageWidth/2;
private var vpY:Number=stage.stageHeight/2;
public function RotateY() {
init();
}
private function init():void {
balls = new Array();
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=new Ball3D(10,Math.random()*0xffffff);
balls.push(ball);
ball.xpos=Math.random()*200-100;
ball.ypos=Math.random()*200-100;
ball.zpos=(Math.random()*2-1)*100;
addChild(ball);
}
addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
private function onEnterFrame(event:Event):void {
var angleY:Number = (mouseX - vpX) * .0004;//旋转的角度与鼠标的水平位置关联
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=balls[i];
rotateY(ball, angleY);
}
sortZ();
}
//绕y轴旋转
private function rotateY(ball:Ball3D, angleY:Number):void {
var cosY:Number=Math.cos(angleY);
var sinY:Number=Math.sin(angleY);
var x1:Number=ball.xpos*cosY-ball.zpos*sinY;
var z1:Number=ball.zpos*cosY+ball.xpos*sinY;
ball.xpos=x1;
ball.zpos=z1;
if (ball.zpos>- fl) {
var scale:Number = fl / (fl + ball.zpos);
ball.scaleX=ball.scaleY=scale;
ball.x=vpX+ball.xpos*scale;
ball.y=vpY+ball.ypos*scale;
ball.alpha = scale*0.8;
ball.visible=true;
} else {
ball.visible=false;
}
}
private function sortZ():void {
balls.sortOn("zpos", Array.DESCENDING | Array.NUMERIC);
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=balls[i];
setChildIndex(ball, i);
}
}
}
}这个示例还可以扩充到3个轴的同时旋转：
var balls:Array;
var numBalls:uint=50;
var fl:Number=250;
var vpx:Number=stage.stageWidth/2;
var vpy:Number=stage.stageHeight/2;
function init():void {
balls=new Array(numBalls);
for (var i:uint=0; i<numBalls; i++) {
var ball:Ball3D=new Ball3D(10,Math.random()*0xffffff);
balls[i]=ball;
ball.xpos = (Math.random()*2-1)*100;
ball.ypos = (Math.random()*2-1)*100;
ball.zpos = (Math.random()*2-1)*100;
addChild(ball);
}
addEventListener(Event.ENTER_FRAME,EnterFrameHandler);
}
function EnterFrameHandler(e:Event):void {
var dx:Number = mouseX - vpx;
var dy:Number = mouseY - vpy;
var angleY:Number =dx*0.0005;
var angleX:Number =dy*0.0005;
var angleZ:Number = Math.sqrt(dx*dx + dy*dy)*0.0005;
if (dx>0){angleZ *=-1;}//以鼠标所在点的x坐标相对于消失点的位置为判断依据，左侧z轴正向旋转，右侧z轴反向旋转
for (var i:uint; i<numBalls; i++) {
var b:Ball3D=balls[i];
rotateX(b,angleX);
rotateY(b,angleY);
rotateZ(b,angleZ);
doPerspective(b);
}
sortZ();
}
//x轴的坐标旋转
function rotateX(ball:Ball3D, angleX:Number):void {
var cosX:Number=Math.cos(angleX);
var sinX:Number=Math.sin(angleX);
var y1:Number=ball.ypos*cosX-ball.zpos*sinX;
var z1:Number=ball.zpos*cosX+ball.ypos*sinX;
ball.ypos=y1;
ball.zpos=z1;
}
//y轴的坐标旋转
function rotateY(ball:Ball3D, angleY:Number):void {
var cosY:Number=Math.cos(angleY);
var sinY:Number=Math.sin(angleY);
var x1:Number=ball.xpos*cosY-ball.zpos*sinY;
var z1:Number=ball.zpos*cosY+ball.xpos*sinY;
ball.xpos=x1;
ball.zpos=z1;
}
//z轴的坐标旋转
function rotateZ(ball:Ball3D, angleZ:Number):void {
var cosZ:Number=Math.cos(angleZ);
var sinZ:Number=Math.sin(angleZ);
var x1:Number=ball.xpos*cosZ-ball.ypos*sinZ;
var y1:Number=ball.ypos*cosZ+ball.xpos*sinZ;
ball.xpos=x1;
ball.ypos=y1;
}
//3D透视处理
function doPerspective(ball:Ball3D):void {
if (ball.zpos>-fl) {
var scale:Number = fl / (fl + ball.zpos);
ball.scaleX=ball.scaleY=scale;
ball.x=vpx+ball.xpos*scale;
ball.y=vpy+ball.ypos*scale;
//ball.alpha = scale*0.65;
ball.visible=true;
} else {
ball.visible=false;
}
}
//z轴排序
function sortZ():void {
balls.sortOn("zpos",Array.DESCENDING|Array.NUMERIC);
for (var i:uint=0; i<numBalls; i++) {
setChildIndex(balls[i],i);
}
}
init();3D碰撞检测：
基本原理仍然可以套用前面讲过的“基于距离的检测”，当二个球之间的距离小于二球的半径合时，即认为发生了碰撞，至于碰撞检测出来以后再如何处理，就要发挥想象了
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.geom.ColorTransform;
public class Collision3D extends Sprite {
private var balls:Array;
private var numBalls:uint=8;
private var fl:Number=250;
private var vpX:Number=stage.stageWidth/2;
private var vpY:Number=stage.stageHeight/2;
private var top:Number=-100;
private var bottom:Number=100;
private var left:Number=-100;
private var right:Number=100;
private var front:Number=100;
private var back:Number=-100;
public function Collision3D() {
init();
}
private function init():void {
balls = new Array();
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=new Ball3D(10);
balls.push(ball);
ball.xpos=Math.random()*400-200;
ball.ypos=Math.random()*400-200;
ball.zpos=Math.random()*400-200;
ball.vx=Math.random()*10-5;
ball.vy=Math.random()*10-5;
ball.vz=Math.random()*10-5;
addChild(ball);
}
addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
private function onEnterFrame(event:Event):void {
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=balls[i];
move(ball);
}
for (i = 0; i < numBalls - 1; i++) {
var ballA:Ball3D=balls[i];
for (var j:uint = i + 1; j < numBalls; j++) {
var ballB:Ball3D=balls[j];
var dx:Number=ballA.xpos-ballB.xpos;
var dy:Number=ballA.ypos-ballB.ypos;
var dz:Number=ballA.zpos-ballB.zpos;
var dist:Number=Math.sqrt(dx*dx+dy*dy+dz*dz);
if (dist<ballA.radius+ballB.radius) {
var newTransform:ColorTransform =
new ColorTransform(0, 1, 1, 1, Math.random()*255, Math.random()*255, Math.random()*255, 0);
ballA.transform.colorTransform=newTransform;
ballB.transform.colorTransform=newTransform;
}
}
}
sortZ();
}
private function move(ball:Ball3D):void {
var radius:Number=ball.radius;
ball.xpos+=ball.vx;
ball.ypos+=ball.vy;
ball.zpos+=ball.vz;
if (ball.xpos+radius>right) {
ball.xpos=right-radius;
ball.vx*=-1;
} else if (ball.xpos - radius < left) {
ball.xpos=left+radius;
ball.vx*=-1;
}
if (ball.ypos+radius>bottom) {
ball.ypos=bottom-radius;
ball.vy*=-1;
} else if (ball.ypos - radius < top) {
ball.ypos=top+radius;
ball.vy*=-1;
}
if (ball.zpos+radius>front) {
ball.zpos=front-radius;
ball.vz*=-1;
} else if (ball.zpos - radius < back) {
ball.zpos=back+radius;
ball.vz*=-1;
}
if (ball.zpos>- fl) {
var scale:Number = fl / (fl + ball.zpos);
ball.scaleX=ball.scaleY=scale;
ball.x=vpX+ball.xpos*scale;
ball.y=vpY+ball.ypos*scale;
ball.visible=true;
} else {
ball.visible=false;
}
}
private function sortZ():void {
balls.sortOn("zpos", Array.DESCENDING | Array.NUMERIC);
for (var i:uint = 0; i < numBalls; i++) {
var ball:Ball3D=balls[i];
setChildIndex(ball, i);
}
}
}
}上面的示例中，生二球发生碰撞后，颜色变为随机色（当然您可以处理根据前面讲过的动量守恒原理对速度做处理，不过在3D空间中要同时计算x,y,z三个轴的速度大小以及方向，运算量是比较大的，各位有兴趣可自行尝试）
本文参与 腾讯云自媒体分享计划，分享自作者个人站点/博客。
原始发表：2010-05-08 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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