Mesh, Surface, SkyBox, and WireFrame

原文地址:http://wiki.alternativaplatform.com/Alternativa_8_for_Dummies_Part_III

1:Mesh

Mesh是所有多边形的集合，它也是Box, Decal, GeoSphere, Skin ,SkyBox的基类~只需记住在A3D中，几乎所有在三维空间中的多边形都是Mesh

2:Surface

面~~每个多边形都可以分割成N多个面，每个面都拥有自己的材质，一个面由一连串的三角形组成。

public function addSurface(material:Material, indexBegin:uint, numTriangles:uint):Surface

material:Material — surface material
indexBegin:uint — Start index in IndexBuffer.
numTriangles:uint — number of triangles

box = new Box(200, 200, 200); //create box
rootContainer.addChild(box);
 
for (var i:int = 0; i < 6; i++) { //box to add 6 surfaces
     var texture:BitmapTextureResource = new BitmapTextureResource(new aLogo[i]().bitmapData); 
     box.addSurface(new TextureMaterial(texture), i*6, 2); //each impose its texture
}

3：SkyBox

天空盒。简单来说就是一个6面体，材质贴图都在内部，而摄像机处于天空盒当中，就能构建一般游戏中的最外层的背景图。当然，GeoSphere同样可以作为天空盒使用。

public function SkyBox(size:Number, left:Material = null, 
                                    right:Material = null, 
                                    back:Material = null, 
                                    front:Material = null, 
                                    bottom:Material = null, 
                                    top:Material = null, 
                                    uvPadding:Number = 0);

4：WireFrame

线框。可以将任意3D模型转化为三维线框。看图比较直接...

Mesh:

Wireframe:

源码：

var parser:ParserA3D = new ParserA3D(); 
    parser.parse(new A3dModel());
    car =  parser.objects[1] as Mesh;
 
    carWireFrame = WireFrame.createEdges(car, 0xFFFFFFFF, 1, 1); //transform the mesh into three-dimensional line.
    rootContainer.addChild(carWireFrame);//add to a container

createEdges的四个参数分别为：Mesh, 颜色, 透明度, 线框粗细

我们也可以使用

createLinesList(points:Vector, color:uint = 0, alpha:Number = 1, thickness:Number = 1):WireFrame

方法来自己画一个线框：

var pointsVector:Vector.<Vector3D> = Vector.<Vector3D>([new Vector3D(  70, -70,  70), new Vector3D(  70,  70,  70), 
                                                        new Vector3D(  70,  70,  70), new Vector3D( -70,  70,  70), 
                                                        new Vector3D( -70,  70,  70), new Vector3D( -70, -70,  70), 
                                                        new Vector3D( -70, -70,  70), new Vector3D(  70, -70,  70),
                                                        new Vector3D(  70, -70, -70), new Vector3D(  70,  70, -70), 
                                                        new Vector3D(  70,  70, -70), new Vector3D( -70,  70, -70),
                                                        new Vector3D( -70,  70, -70), new Vector3D( -70, -70, -70), 
                                                        new Vector3D( -70, -70, -70), new Vector3D(  70, -70, -70),
                                                        new Vector3D(  70, -70,  70), new Vector3D(  70, -70, -70), 
                                                        new Vector3D(  70,  70,  70), new Vector3D(  70,  70, -70), 
                                                        new Vector3D( -70,  70,  70), new Vector3D( -70,  70, -70),
                                                        new Vector3D( -70, -70,  70), new Vector3D( -70, -70, -70)]);
wireFrame = WireFrame.createLinesList(pointsVector, 0xFF00FF00, 1, 3); //pass the vector points, color, alpha and size of lines
rootContainer.addChild(wireFrame);