繼續(xù)上次的學(xué)習(xí)，接下來要試試攝像機(jī)的移動了。
這里需要涉及幾個概念，攝像機(jī)的坐標(biāo)（x, y, z）和視覺角度（LookAt）
攝像機(jī)的位置可以使用（x, y, z）來定位；
視覺角度可以定義如何通過窗口來看場景。
lookAt(p_nX:Number, p_nY:Number, p_nZ:Number)
如：lookAt(0,0,0);//可以理解為通過攝像機(jī)的位置看場景。

攝像機(jī)的移動方式比較有意思，如果直接修改x、y、z坐標(biāo)，視覺效果會與現(xiàn)實(shí)看到的情況相同；
而tilt、pan則是與場景平行移動；
roll是以z軸移動，通過攝像機(jī)視野看上去是攝像機(jī)的旋轉(zhuǎn)效果。

額外說一下 Line3D 是在場景中繪制了線段，這里用做參考線，代碼不難理解我就不過多解釋了。

代碼如下：

package
{
import flash.display.Sprite;
import flash.events.*;
import flash.ui.*;
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.Loader;
import flash.net.URLRequest;
import sandy.core.Scene3D;
import sandy.core.scenegraph.*;
import sandy.primitive.*;
import sandy.materials.*;
import sandy.materials.attributes.*;
import sandy.core.data.*;

/**
* ...
* @author ever5u
*/
public class fuxi extends Sprite
{
private var scene:Scene3D;
private var camera:Camera3D;
public function fuxi() {
//創(chuàng)建一個攝像機(jī)
camera = new Camera3D(300, 300);
camera.x = 100;
camera.y = 100;
camera.z = -300;
camera.lookAt(0,0,0);
//創(chuàng)建一個 Group
var root:Group = createScene();
//創(chuàng)建場景
scene = new Scene3D( "scene", this, camera, root );
//創(chuàng)建實(shí)時偵聽
addEventListener( Event.ENTER_FRAME, enterFrameHandler );
stage.addEventListener(KeyboardEvent.KEY_DOWN, keyPressed);
}
var box = new Box("box", 100, 100, 100);
var Plane:Plane3D;
public function createScene() {
var g:Group = new Group();

//在場景畫一個坐標(biāo)定位點(diǎn)
Plane = new Plane3D("Texture", 300, 300);
var myXLine:Line3D = new Line3D( "x-coord", new Point3D( -20, 0, 0), new Point3D( 20, 0, 0 ));
var myYLine:Line3D = new Line3D( "y-coord", new Point3D(0, -20, 0), new Point3D( 0, 20, 0 ));
var myZLine:Line3D = new Line3D( "z-coord", new Point3D(0, 0, -20), new Point3D( 0, 0, 20 ));

g.addChild(myXLine);
g.addChild(myYLine);
g.addChild(myZLine);
g.addChild( box );
return g;
}
public function enterFrameHandler(_evt:Event) {
box.rotateX = mouseX;
box.rotateY = mouseY;
scene.render();
}
public function keyPressed(_evt:KeyboardEvent):void {
switch(_evt.keyCode) {
case Keyboard.UP:
camera.tilt += 2;
//camera.y -= 2;
break;
case Keyboard.DOWN:
camera.tilt -= 2;
//camera.y += 2;
break;
case Keyboard.RIGHT:
camera.pan -= 2;
//camera.x += 2;
break;
case Keyboard.LEFT:
camera.pan += 2;
//camera.x -= 2;
break;
case Keyboard.CONTROL:
camera.roll += 2;
break;
case Keyboard.PAGE_DOWN:
camera.z -= 5;
break;
case Keyboard.PAGE_UP:
camera.z += 5;
break;
}
}
}

}

效果：

還有場景自適應(yīng)的問題，需要說明一下。

攝像機(jī)的鏡頭可視角度使用 fov（vertical field of view angle）來定義。

換算公式：

var fl:Numer = (viewport.height / 2) / Math.tan (camera.fov / 2 * (Math.PI / 180));

代碼：

package
{
import flash.display.Sprite;
import flash.events.*;
import flash.ui.*;
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.Loader;
import flash.net.URLRequest;
import flash.display.Stage;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
import sandy.core.Scene3D;
import sandy.core.scenegraph.*;
import sandy.primitive.*;
import sandy.materials.*;
import sandy.materials.attributes.*;
import sandy.core.data.*;

/**
* ...
* @author ever5u
*/
public class fuxi extends Sprite
{
private var scene:Scene3D;
private var camera:Camera3D;
public function fuxi() {
stage.scaleMode = StageScaleMode.NO_SCALE;
stage.align = StageAlign.TOP_LEFT;
//創(chuàng)建一個攝像機(jī)
camera = new Camera3D(300, 300);
camera.x = 100;
camera.y = 100;
camera.z = -300;
camera.lookAt(0,0,0);
//創(chuàng)建一個 Group
var root:Group = createScene();
//創(chuàng)建場景
scene = new Scene3D( "scene", this, camera, root );
//創(chuàng)建實(shí)時偵聽
addEventListener( Event.ENTER_FRAME, enterFrameHandler );
stage.addEventListener (Event.RESIZE, onResize);
}
var box = new Box("box", 100, 100, 100);
var Plane:Plane3D;
public function createScene() {
var g:Group = new Group();

//在場景畫一個坐標(biāo)定位點(diǎn)
Plane = new Plane3D("Texture", 300, 300);
var myXLine:Line3D = new Line3D( "x-coord", new Point3D( -20, 0, 0), new Point3D( 20, 0, 0 ));
var myYLine:Line3D = new Line3D( "y-coord", new Point3D(0, -20, 0), new Point3D( 0, 20, 0 ));
var myZLine:Line3D = new Line3D( "z-coord", new Point3D(0, 0, -20), new Point3D( 0, 0, 20 ));

g.addChild(myXLine);
g.addChild(myYLine);
g.addChild(myZLine);
g.addChild( box );
return g;
}
public function enterFrameHandler(_evt:Event) {
box.rotateX = mouseX;
box.rotateY = mouseY;
scene.render();
}
function onResize (e:Event):void{
// 獲取場景寬高
var w:Number = stage.stageWidth;
var h:Number = stage.stageHeight;
// 設(shè)置視野寬高
scene.camera.viewport.width = w;
scene.camera.viewport.height = h;
// 獲取物體box與攝像機(jī)間的距離
var d:Number = box.getPosition ("camera").getNorm ();
// 保持?jǐn)z像機(jī)觀看比例
scene.camera.fov = 2 * Math.atan2 (h / 2, d) * (180 / Math.PI);
// 執(zhí)行渲染
scene.render();
}
}

}

效果：

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