Flash3D学习计划（三）——学习VB，IB相关，理解三角形顶点顺序；在屏幕上显示2D矩形，并实现缩放，平移，旋转

VB：顶点缓冲
IB: 顶点索引缓冲
三角形的顶点顺序决定了三角形是顺时针还是逆时针，从而决定了三角形在背面剔除的过程中是否会被剔除掉。
相关理论知识可以在前面的文章中找到更多的说明。
实现效果
主要代码
  1 package
  2 {
  3     import com.adobe.utils.AGALMiniAssembler;
  4     import com.adobe.utils.PerspectiveMatrix3D;
  5     
  6     import flash.display.Sprite;
  7     import flash.display.Stage3D;
  8     import flash.display3D.Context3D;
  9     import flash.display3D.Context3DProgramType;
 10     import flash.display3D.Context3DVertexBufferFormat;
 11     import flash.display3D.IndexBuffer3D;
 12     import flash.display3D.Program3D;
 13     import flash.display3D.VertexBuffer3D;
 14     import flash.events.Event;
 15     import flash.geom.Matrix3D;
 16     import flash.geom.Vector3D;
 17     
 18     /**
 19      * @author smartqi
 20      * @E-mail: 
 21      * 创建时间：2013-6-29 上午9:36:36
 22      * 
 23      */
 24     public class RectangleTest extends Sprite
 25     {
 26         
 27         private var context:Context3D;
 28         private var vertexBuff:VertexBuffer3D;
 29         private var indexBuff:IndexBuffer3D;
 30         private var vertexData:Vector.<Number>;
 31         private var indexData:Vector.<uint>;
 32         private var shaderProgram:Program3D;
 33         private var perspectiveMatrix:PerspectiveMatrix3D;
 34         private var i:int;
 35         private var sign:int = 1;
 36         private const angleGap:Number = 20;
 37         private var angle:Number = 0;
 38         private var modelMatrix:Matrix3D;
 39         private var viewMatrix:Matrix3D;
 40         private var finalMatrix:Matrix3D;
 41         
 42         
 43         public function RectangleTest()
 44         {
 45             var stage3d:Stage3D = stage.stage3Ds[0];
 46             stage3d.addEventListener(Event.CONTEXT3D_CREATE,onContextCreate);
 47             stage3d.requestContext3D();
 48         }
 49         
 50         private function onContextCreate(e:Event):void{
 51             context = (e.target as Stage3D).context3D;
 52             if(context == null) return;
 53             context.enableErrorChecking = true; //允许进行错误检测，release版本应设置
 54             context.configureBackBuffer(500,500,0); //设置显示区域的大小
 55             setupVertexBuff(); //设置顶点缓冲
 56             setupShaderProgram(); //设置shander
 57             setupPerspectiveMatrix(); //设置投影矩阵
 58             initMatrix();
 59             addEventListener(Event.ENTER_FRAME,onEnterFrame);
 60         }
 61         
 62         private function setupVertexBuff():void{
 63             vertexData = Vector.<Number>([
 64                 // x    y     z     r     g     b
 65                 40,        40,        -40,    1,    0,    0,
 66                 40,        -40,    -40,    0,    1,    0,
 67                 -40,    -40,    -40,    0,    0,    1,
 68                 -40,    40,        -40,    1,    1,    1,
 69             ]);
 70             
 71             indexData = Vector.<uint>([0,1,2,0,2,3]);
 72             vertexBuff = context.createVertexBuffer(4,vertexData.length/4);
 73             vertexBuff.uploadFromVector(vertexData,0,4);
 74             indexBuff = context.createIndexBuffer(6);
 75             indexBuff.uploadFromVector(indexData,0,6);
 76             context.setVertexBufferAt(0,vertexBuff,0,Context3DVertexBufferFormat.FLOAT_3);
 77             context.setVertexBufferAt(1,vertexBuff,3,Context3DVertexBufferFormat.FLOAT_3);
 78         }
 79         
 80         private function setupShaderProgram():void{
 81             var vertexProgram:AGALMiniAssembler =  new AGALMiniAssembler();
 82             vertexProgram.assemble(Context3DProgramType.VERTEX,
 83                 "m44 op,va0,vc0
" +
 84                 "mov v1,va1
");
 85             var fragmentProgram:AGALMiniAssembler = new AGALMiniAssembler();
 86             fragmentProgram.assemble(Context3DProgramType.FRAGMENT,
 87                 "mov oc,v1");
 88             shaderProgram = context.createProgram();
 89             shaderProgram.upload(vertexProgram.agalcode,fragmentProgram.agalcode);
 90             context.setProgram(shaderProgram);
 91         }
 92         
 93         private function setupPerspectiveMatrix():void{
 94             perspectiveMatrix = new PerspectiveMatrix3D();
 95             perspectiveMatrix.perspectiveFieldOfViewRH(Math.PI*90/180,1,1,1000);  //注意这里的角度使用的是弧度
 96         }
 97         
 98         private function initMatrix():void{
 99             modelMatrix = new Matrix3D();
100             viewMatrix = new Matrix3D();
101             finalMatrix = new Matrix3D();
102         }
103         
104         private function onEnterFrame(e:Event):void{
105             context.clear(0,0,0);
106             angle += angleGap;
107             modelMatrix.identity();
108             modelMatrix.prependRotation(angle,Vector3D.Z_AXIS);  //绕着Z轴旋转物体，注意这里的角度使用的是角度
109             if(i>30){
110                 sign = -1;
111             }
112             if(i<0){
113                 sign = 1;
114             }
115             i += sign;
116             viewMatrix.identity();
117             viewMatrix.prependTranslation(0,0,-30 + i); //将相机向后移，使物体看起来变小了,将相机向前移，使物体看起来变大
118             finalMatrix.identity();
119             finalMatrix.append(modelMatrix);
120             finalMatrix.append(viewMatrix);
121             finalMatrix.append(perspectiveMatrix);
122             context.setProgramConstantsFromMatrix(Context3DProgramType.VERTEX,0,finalMatrix,true); //上传最终的顶点转换矩阵，注意这里最后一个参数为true
123             context.drawTriangles(indexBuff,0,2);
124             context.present();
125         }
126     }
127 }