away3d camera note

away3d camera note
camera 相關原理可以先參考這兩篇
http://www.flashmagazine.com/Tutorials/detail/away3d_basics_the_cameras/
http://blog.tartiflop.com/2008/08/understanding-zoom-focus-and-field-of-view-in-papervision3d/
away3d 有四種 camera，分別是
camera3D：default camera
TargetCamera3D：automatically look at a specified target object
SpringCam：1st and 3rd person camera
HoverCamera3D：hover round a specified target object

本文介紹(最常用) HoverCamera3D，
利用改變 camera.panAngle 及 camera.tileAngle
來產生旋轉及放大縮小的 3D 效果。

	package
	{
	import away3d.cameras.HoverCamera3D;
	import away3d.containers.ObjectContainer3D;
	import away3d.containers.Scene3D;
	import away3d.containers.View3D;
	import away3d.materials.VideoMaterial;
	import away3d.primitives.Cube;
	import away3d.primitives.Trident;
	import flash.display.Sprite;
	import flash.display.StageAlign;
	import flash.display.StageScaleMode;
	import flash.events.Event;
	import flash.events.MouseEvent;
	public class Main extends Sprite
	{
	private var scene:Scene3D;
	private var view:View3D;
	private var material:VideoMaterial;
	private var cube:Cube;
	private var container:ObjectContainer3D;
	private var lastRotationX:Number;
	private var lastRotationY:Number;
	private var move:Boolean;
	private var lastMouseY:Number;
	private var lastMouseX:Number
	private var camera:HoverCamera3D;;
	private var lastPanAngle:Number;
	private var lastTiltAngle:Number;
	public function Main():void
	{
	if (stage)
	init();
	else
	addEventListener(Event.ADDED_TO_STAGE, init);
	}
	private function init(e:Event = null):void
	{
	removeEventListener(Event.ADDED_TO_STAGE, init);
	// entry point
	stage.align = StageAlign.TOP_LEFT;
	stage.scaleMode = StageScaleMode.NO_SCALE;
	init3D();
	}
	private function init3D():void
	{
	scene = new Scene3D();
	camera = new HoverCamera3D();
	camera.z = -1000; // make sure the camera is positioned away from the default 0,0,0 coordinate
	camera.panAngle = 45;
	camera.tiltAngle = 5;
	camera.hover(true);
	camera.minTiltAngle = -90;
	view = new View3D();
	view.x = stage.stageWidth / 2;
	view.y = stage.stageHeight / 2;
	view.scene = scene;
	view.camera = camera;
	addChild(view);
	var axis:Trident = new Trident(250, true);
	scene.addChild(axis);
	// 拿 flv 的材質
	material = new VideoMaterial();
	material.loop = true;
	material.file = "video/1.flv";
	material.smooth = true;
	cube = new Cube();
	cube.material = material;
	cube.width = 200;
	cube.height = 200;
	cube.depth = 200;
	container = new ObjectContainer3D(cube);
	scene.addChild(container);
	addEventListener(Event.ENTER_FRAME, _onEnterFrame);
	addEventListener(Event.ADDED_TO_STAGE, _onAddedToStage);
	}
	private function _onAddedToStage(e:Event):void
	{
	removeEventListener(Event.ADDED_TO_STAGE, _onAddedToStage);
	view.x = stage.stageWidth / 2;
	view.y = stage.stageHeight / 2;
	stage.addEventListener(MouseEvent.MOUSE_DOWN, onMouseDown);
	stage.addEventListener(MouseEvent.MOUSE_UP, onMouseUp);
	}
	private function onMouseUp(e:MouseEvent):void
	{
	move = false;
	}
	private function onMouseDown(e:MouseEvent):void
	{
	lastPanAngle = camera.panAngle;
	lastTiltAngle = camera.tiltAngle;
	lastMouseX = mouseX;
	lastMouseY = mouseY;
	move = true;
	}
	private function _onEnterFrame(e:Event):void
	{
	var cameraSpeed:Number = 0.3; // Approximately same speed as mouse movement.
	if (move) {
	camera.panAngle = cameraSpeed*(stage.mouseX - lastMouseX) + lastPanAngle;
	camera.tiltAngle = cameraSpeed*(stage.mouseY - lastMouseY) + lastTiltAngle;
	}
	camera.hover();
	view.render();
	}
	}
	}

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