opengles绘制可旋转的六角星

package com.bn.Sample5_1;

import android.opengl.Matrix;

//存储系统矩阵状态的类
public class MatrixState 
{
	private static float[] mProjMatrix = new float[16];//4x4矩阵 投影用
    private static float[] mVMatrix = new float[16];//摄像机位置朝向9参数矩阵
    private static float[] mMVPMatrix;//最后起作用的总变换矩阵
    
    //设置摄像机
    public static void setCamera
    (
    		float cx,	//摄像机位置x
    		float cy,   //摄像机位置y
    		float cz,   //摄像机位置z
    		float tx,   //摄像机目标点x
    		float ty,   //摄像机目标点y
    		float tz,   //摄像机目标点z
    		float upx,  //摄像机UP向量X分量
    		float upy,  //摄像机UP向量Y分量
    		float upz   //摄像机UP向量Z分量		
    )
    {
    	Matrix.setLookAtM
        (
        		mVMatrix, 
        		0, 
        		cx,
        		cy,
        		cz,
        		tx,
        		ty,
        		tz,
        		upx,
        		upy,
        		upz
        );
    }
    
    //设置正交投影参数
    public static void setProjectOrtho
    (
    	float left,		//near面的left
    	float right,    //near面的right
    	float bottom,   //near面的bottom
    	float top,      //near面的top
    	float near,		//near面距离
    	float far       //far面距离
    )
    {    	
    	Matrix.orthoM(mProjMatrix, 0, left, right, bottom, top, near, far);
    }   
   
    //获取具体物体的总变换矩阵
    public static float[] getFinalMatrix(float[] spec)
    {
    	mMVPMatrix=new float[16];
    	Matrix.multiplyMM(mMVPMatrix, 0, mVMatrix, 0, spec, 0);
        Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mMVPMatrix, 0);        
        return mMVPMatrix;
    }
}

package com.bn.Sample5_1;
import android.opengl.GLSurfaceView;
import android.view.MotionEvent;
import android.opengl.GLES20;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;
import android.content.Context;

class MySurfaceView extends GLSurfaceView 
{
	private final float TOUCH_SCALE_FACTOR = 180.0f/320;//角度缩放比例
    private SceneRenderer mRenderer;//场景渲染器
	 
	private float mPreviousY;//上次的触控位置Y坐标
    private float mPreviousX;//上次的触控位置X坐标
	
	public MySurfaceView(Context context) {
        super(context);
        this.setEGLContextClientVersion(2); //设置使用OPENGL ES2.0
        mRenderer = new SceneRenderer();	//创建场景渲染器
        setRenderer(mRenderer);				//设置渲染器		        
        setRenderMode(GLSurfaceView.RENDERMODE_CONTINUOUSLY);//设置渲染模式为主动渲染   
    }
	
	//触摸事件回调方法
    @Override 
    public boolean onTouchEvent(MotionEvent e) {
        float y = e.getY();
        float x = e.getX();
        switch (e.getAction()) {
        case MotionEvent.ACTION_MOVE:
            float dy = y - mPreviousY;//计算触控笔Y位移
            float dx = x - mPreviousX;//计算触控笔X位移            
            for(SixPointedStar h:mRenderer.ha)
            {
            	h.yAngle += dx * TOUCH_SCALE_FACTOR;//设置六角星数组中的各个六角星绕y轴旋转角度
                h.xAngle+= dy * TOUCH_SCALE_FACTOR;//设置六角星数组中的各个六角星绕x轴旋转角度
            }
        }
        mPreviousY = y;//记录触控笔位置
        mPreviousX = x;//记录触控笔位置
        return true;
    }

	private class SceneRenderer implements GLSurfaceView.Renderer 
    {   
    	SixPointedStar[] ha=new SixPointedStar[6];//六角星数组
    	
        public void onDrawFrame(GL10 gl) 
        { 
        	//清除深度缓冲与颜色缓冲
            GLES20.glClea