AS3:参数child必须为非空

Question

从YouTube做增强现实应用tut。我是整个FLARTool工具包和papervision工作人员的新手。永远感谢那些帮助者。我有这个脚本:

package
{
import flash.display.BitmapData;
import flash.display.Sprite;
import flash.events.Event;
import flash.media.Camera;
import flash.media.Video;
import flash.utils.ByteArray;
import org.libspark.flartoolkit.core.FLARCode;
import org.libspark.flartoolkit.core.param.FLARParam;
import org.libspark.flartoolkit.core.raster.rgb.FLARRgbRaster_BitmapData;
import org.libspark.flartoolkit.core.transmat.FLARTransMatResult;
import org.libspark.flartoolkit.detector.FLARSingleMarkerDetector;
import org.libspark.flartoolkit.support.pv3d.FLARBaseNode;
import org.libspark.flartoolkit.support.pv3d.FLARCamera3D;
import org.papervision3d.lights.PointLight3D;
import org.papervision3d.materials.BitmapFileMaterial;
import org.papervision3d.materials.utils.MaterialsList;
import org.papervision3d.objects.primitives.Cube;
import org.papervision3d.render.BasicRenderEngine;
import org.papervision3d.scenes.Scene3D;
import org.papervision3d.view.Viewport3D;
[SWF(width="640", height="480", frameRate="30", backgroundColor="#ffffff")]
public class test extends Sprite
{
    [Embed(source="marker15.pat", mimeType="application/octet-stream")]
    private var marker:Class;
    [Embed(source="camera_para.dat", mimeType="application/octet-stream")]
    private var cam_params:Class;
    //createFLAR variables
    private var ar_params:FLARParam;
    private var ar_marker:FLARCode;
    //createCam variables
    private var ar_vid:Video
    private var ar_cam:Camera
    //createBMP vairiables
    private var ar_bmp:BitmapData;
    private var ar_raster:FLARRgbRaster_BitmapData;
    private var ar_detection:FLARSingleMarkerDetector;
    //createPapervision variables
    private var ar_scene:Scene3D;
    private var ar_3dcam:org.libspark.flartoolkit.support.pv3d.FLARCamera3D;
    private var ar_basenode:FLARBaseNode;
    private var ar_viewport:Viewport3D;
    private var ar_renderengine:BasicRenderEngine;
    private var ar_transmat:FLARTransMatResult;
    private var ar_cube:Cube;
    public function test()
    {
        createFLAR();
        createCam();
        createBMP();
        createPapervision();
        addEventListener(Event.ENTER_FRAME, loop);
    }
    public function createFLAR()
    {
        ar_params= new FLARParam();
        ar_marker= new FLARCode(16,16);
        ar_params.loadARParam(new cam_params() as ByteArray);
        ar_marker.loadARPatt(new marker()); 
    }
    public function createCam()
    {
        ar_vid= new Video(640, 480);
        ar_cam= Camera.getCamera();
        ar_cam.setMode(640,480,30);
        ar_vid.attachCamera(ar_cam);
        addChild(ar_vid);
    }
    public function createBMP()
    {
        ar_bmp= new BitmapData(640,480);
        ar_bmp.draw(ar_vid);
        ar_raster= new FLARRgbRaster_BitmapData(ar_bmp);
        ar_detection= new FLARSingleMarkerDetector(ar_params, ar_marker,80);        
    }
    public function createPapervision()
    {
        ar_scene= new Scene3D();
        ar_3dcam= new org.libspark.flartoolkit.support.pv3d.FLARCamera3D(ar_params);
        ar_basenode= new FLARBaseNode();
        ar_renderengine= new BasicRenderEngine();
        ar_transmat= new FLARTransMatResult();
        var ar_light:PointLight3D= new PointLight3D();
        ar_light.x= 1000;
        ar_light.y= 1000;
        ar_light.z= -1000;
        var ar_bitmap:BitmapFileMaterial;
        ar_bitmap=new BitmapFileMaterial ("LBP2.jpg");
        ar_bitmap.doubleSided=true;
        ar_cube=new Cube(new MaterialsList({all:ar_bitmap}), 80, 80, 80);
        ar_scene.addChild(ar_basenode);
        ar_basenode.addChild(ar_cube);
        addChild(ar_viewport);
    }
    private function loop(e:Event):void
    {
        ar_bmp.draw(ar_vid);
        ar_cube.rotationX +=4;
        ar_cube.rotationY +=6;
        try
        {
            if(ar_detection.detectMarkerLite(ar_raster, 80) && ar_detection.getConfidence()>0.5)
            {
                ar_detection.getTransformMatrix(ar_transmat);
                ar_basenode.setTransformMatrix(ar_transmat);
                ar_renderengine.renderLayers(ar_scene, ar_3dcam, ar_viewport);
            }
        }
        catch (e:Error){}
    }
}
}

当我运行测试时，我得到这个日志:

TypeError:错误#2007:参数子必须非空。在flash.display:: DisplayObjectContainer/addChild ()at test/createPapervision()[C:UsersOmer HacohenAdobe Flash Builder 4.7testsrctest.as:103]at test()[C:UsersOmer HacohenAdobe Flash Builder 4.7testsrctest.as:58]

是什么意思?不需要告诉应用程序打开了相机但是应该位于标记上的立方体没有出现

Answer 1

由于createPapervision方法中的以下行，您正在收到错误:

addChild(ar_viewport);

从你发布的代码，你从来没有初始化该变量(ar_viewport)，所以它是空的，当你试图添加它。

试试这个:

ar_viewport = new Viewport3D(stage.stageWidth,stage.stageHeight);
addChild(ar_viewport);