m3gcanvas.java

Java ME手机应用开发大全一书的配套光盘上的源码

import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;
import javax.microedition.m3g.*;

class M3GCanvas extends GameCanvas implements Runnable{
  
    private Graphics3D g3d; // 声明用来绘制世界的Graphics3D对象
    private World world; //声明包含摄像机和金字塔多面体的世界对象 
    private Camera camera; //声明摄像机对象 
    private Mesh pyramidMesh; // 声明金字塔多面体对象
    
    public M3GCanvas(){
        super(false);
        //设置全屏模式
        setFullScreenMode(true);
        //创建Graphics3D实例
        g3d = Graphics3D.getInstance();
		//创建世界实例
        world = new World();
        //创建摄像机实例
        camera = new Camera();
        world.addChild(camera); //将摄像机添加到世界中 
        float w = getWidth();
        float h = getHeight();

        // 设置摄像机为透视模式
        camera.setPerspective(60.0f, w / h, 0.1f, 50f);
        //创建金字塔多面体实例
        pyramidMesh = createpyramid(); 
        pyramidMesh.setTranslation(0.0f, 0.0f, -3.0f); 
        world.addChild(pyramidMesh); // 将金字塔多面体添加到世界中
        //设置当前摄像机为场景的活动摄像机
        world.setActiveCamera(camera);
		//启动金字塔旋转的线程
        Thread t = new Thread(this);
        t.start();
    }
    //定义绘制3D场景的方法
    public void draw3D(Graphics g){
        try{
            g3d.bindTarget(g); // 将Graphics对象绑定到Graphics3D对象上
            g3d.render(world); // 绘制世界场景
        }finally{
            g3d.releaseTarget();
        }
    }

    public void run() {
        Graphics g = getGraphics();

        while(true){
            // 金字塔环绕Y轴旋转1度
            pyramidMesh.postRotate(3.0f, 0.0f, 1.0f, 0.0f);
            draw3D(g);
            flushGraphics();
        }
    }


    // 创建金字塔多面体的方法
    private Mesh createpyramid(){  
        // 定义顶点数组要用到的顶点坐标
        short []POINTS = new short[] {-1, -1, 1, 
                                      1, -1, 1, 
                                      1, -1, -1, 
                                      -1, -1, -1, 
                                      0, 1, 0}; 
                                                            
        // The points sequence.
        int []INDICES = new int[] {0, 1, 4, 1, 2, 4, 2, 3, 4, 3, 0, 4, 2, 1, 0, 2, 0, 3};
        byte []COLORS = new byte[] {127, 0, 0, //红色
                                    0, 127, 0,  //绿色
                                    0, 0, 127, //蓝色
                                    127, 0, 127, 
                                    0, 127, 127};
                                                        

        // 金字塔由6个三角带组成
        int []LENGTH = new int[] {3, 3, 3, 3, 3, 3}; 
        //声明顶点数组
        VertexArray POSITION_ARRAY, COLOR_ARRAY;
		//声明索引缓冲
        IndexBuffer INDEX_BUFFER;
        //创建顶点数组
        POSITION_ARRAY = new VertexArray(POINTS.length / 3, 3, 2);
        POSITION_ARRAY.set(0, POINTS.length / 3, POINTS);
        COLOR_ARRAY = new VertexArray(COLORS.length / 3, 3, 1);
        COLOR_ARRAY.set(0, COLORS.length / 3, COLORS);
        INDEX_BUFFER = new TriangleStripArray(INDICES, LENGTH);
		 //用顶点数组创建顶点缓冲
        VertexBuffer vertexBuffer = new VertexBuffer();
        vertexBuffer.setPositions(POSITION_ARRAY, 1.0f, null);
        vertexBuffer.setColors(COLOR_ARRAY);
        
        //创建3D多面体对象
        Mesh mesh = new Mesh(vertexBuffer, INDEX_BUFFER, null);
        //创建外观属性
        Appearance appearance = new Appearance(); 
        PolygonMode polygonMode = new PolygonMode();
        polygonMode.setPerspectiveCorrectionEnable(true);
        polygonMode.setCulling(PolygonMode.CULL_NONE); 
        polygonMode.setShading(PolygonMode.SHADE_SMOOTH);
        appearance.setPolygonMode(polygonMode);
        // 为3D多面体对象设置外观属性
        mesh.setAppearance(0, appearance); 
        return mesh;
    }    

}