public class SixShape {
 private FloatBuffer mVertexBuffer;
 private FloatBuffer mColorBuffer;
 private int mProgram;
 private int mPositionHandle;
 private int mColorHandle;
 private int muMVPMatrixHandle;

 public SixShape(float r) {
  initVetexData(r);
 }

 public void initVetexData(float r) {
  // 初始化頂點坐標
  float[] vertexArray = new float[8*3];
  // 初始化頂點顏色
  float[] colorArray=new float[8*4];
  int j = 0, k = 0;
  vertexArray[j++] = 0;
  vertexArray[j++] = 0;
  vertexArray[j++] = 0;

  colorArray[k++] = 1;
  colorArray[k++] = 1;
  colorArray[k++] = 1;
  colorArray[k++] = 0;
  for (int angle = 0; angle <= 360; angle += 60) {
   vertexArray[j++] = (float) (r*Math.cos(Math.toRadians(angle)));
   vertexArray[j++] = (float) (r*Math.sin(Math.toRadians(angle)));
   vertexArray[j++] = 0;

   colorArray[k++] = 1;
   colorArray[k++] = 0;
   colorArray[k++] = 0;
   colorArray[k++] = 0;
  }
  ByteBuffer buffer = ByteBuffer.allocateDirect(vertexArray.length * 4);
  buffer.order(ByteOrder.nativeOrder());
  mVertexBuffer = buffer.asFloatBuffer();
  mVertexBuffer.put(vertexArray);
  mVertexBuffer.position(0);

  ByteBuffer cbb=ByteBuffer.allocateDirect(colorArray.length*4);
  cbb.order(ByteOrder.nativeOrder());
  mColorBuffer=cbb.asFloatBuffer();
  mColorBuffer.put(colorArray);
  mColorBuffer.position(0);

  int vertexShader = loaderShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);
  int fragmentShader = loaderShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);

  mProgram = GLES20.glCreateProgram();
  GLES20.glAttachShader(mProgram, vertexShader);
  GLES20.glAttachShader(mProgram, fragmentShader);
  GLES20.glLinkProgram(mProgram);

  mPositionHandle = GLES20.glGetAttribLocation(mProgram, "aPosition");
  mColorHandle = GLES20.glGetAttribLocation(mProgram, "aColor");
  muMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");
 }

 public void draw(float[] mvpMatrix) {
  GLES20.glUseProgram(mProgram);
  // 將頂點數據傳遞到管線，頂點著色器
  GLES20.glVertexAttribPointer(mPositionHandle, 3, GLES20.GL_FLOAT, false, 3 * 4, mVertexBuffer);
  // 將頂點顏色傳遞到管線，頂點著色器
  GLES20.glVertexAttribPointer(mColorHandle, 4, GLES20.GL_FLOAT, false,4*4, mColorBuffer);
  // 將變換矩陣傳遞到管線
  GLES20.glUniformMatrix4fv(muMVPMatrixHandle, 1, false, mvpMatrix, 0);
  GLES20.glEnableVertexAttribArray(mPositionHandle);
  GLES20.glEnableVertexAttribArray(mColorHandle);
  // 繪制圖元
  GLES20.glDrawArrays(GLES20.GL_TRIANGLE_FAN, 0, 8);
 }

 private int loaderShader(int type, String shaderCode) {
  int shader = GLES20.glCreateShader(type);
  GLES20.glShaderSource(shader, shaderCode);
  GLES20.glCompileShader(shader);
  return shader;
 }

 private String vertexShaderCode = "uniform mat4 uMVPMatrix;"
   + "attribute vec3 aPosition;"
   + "attribute vec4 aColor;"
   + "varying vec4 aaColor;"
   + "void main(){"
   + "gl_Position = uMVPMatrix * vec4(aPosition,1);"
   + "aaColor = aColor;"
   + "}";

 private String fragmentShaderCode = "precision mediump float;"
   + "varying vec4 aaColor;"
   + "void main(){"
   + "gl_FragColor = aaColor;"
   + "}";

}

public class SixView extends GLSurfaceView{

 public SixView(Context context) {
  super(context);
  setEGLContextClientVersion(2);
  setRenderer(new MyRender());
 }

 class MyRender implements GLSurfaceView.Renderer {
  private SixShape circle;

  @Override
  public void onSurfaceCreated(GL10 gl, EGLConfig config) {
   GLES20.glClearColor(0.5f, 0.5f, 0.5f, 1);
   circle = new SixShape(0.5f);
   GLES20.glEnable(GLES20.GL_DEPTH_TEST);
  }

  // 投影矩陣
  private final float[] mProjectionMatrix = new float[16];
  // 視圖矩陣
  private final float[] mViewMatrix = new float[16];
  // 模型矩陣
  private final float[] mMMatrix = new float[16];
  private final float[] mViewProjectionMatrix = new float[16];
  private final float[] mMVPMatrix = new float[16];

  @Override
  public void onSurfaceChanged(GL10 gl, int width, int height) {
   GLES20.glViewport(0, 0, width, height);
   float ratio= (float) width / height;
   // 設置正交投影
   Matrix.orthoM(mProjectionMatrix, 0, -ratio, ratio, -1, 1, 0, 5);
   // 設置視圖矩陣
   Matrix.setLookAtM(mViewMatrix, 0, 0, 0, 2, 0, 0, 0, 0, 1, 0);
  }

  @Override
  public void onDrawFrame(GL10 gl) {
   GLES20.glClear( GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);
   Matrix.multiplyMM(mViewProjectionMatrix, 0, mProjectionMatrix, 0, mViewMatrix, 0);
   // 設置模型矩陣
   Matrix.setIdentityM(mMMatrix, 0);
   Matrix.translateM(mMMatrix,0,0,0,1);
   Matrix.rotateM(mMMatrix, 0, 30, 0, 0, 1);
   Matrix.multiplyMM(mMVPMatrix, 0, mViewProjectionMatrix, 0, mMMatrix, 0);
   circle.draw(mMVPMatrix);
  }
 }

}