Android开发之绘制平面上的多边形功能分析

public class MyRenderer implements Renderer
{
 float[] triangleData = new float []{
   0.1f,0.6f,0.0f,//上顶点
   -0.3f,0.0f,0.0f,//左顶点
   0.3f,0.1f,0.0f//右顶点
 };
 int[] triangleColor = new int []{
   65535,0,0,0,//上顶点红色
   0,65535,0,0,//左顶点绿色
   0,0,65535,0//右顶点蓝色
 };
 float[] rectData = new float[]{
   0.4f,0.4f,0.0f,//右上顶点
   0.4f,-0.4f,0.0f,//右下顶点
   -0.4f,0.4f,0.0f,//左上顶点
   -0.4f,-0.4f,0.0f//左下顶点
 };
 int[] rectColor = new int []{
   0,65535,0,0,//右上顶点绿色
   0,0,65535,0,//右下顶点蓝色
   65535,0,0,0,//左上顶点红色
   65535,65535,0,0//左下顶点黄色
 };
 float[] rectData2 = new float[]{
   -0.4f,0.4f,0.0f,//左上顶点
   0.4f,0.4f,0.0f,
   0.4f,-0.4f,0.0f,
   -0.4f,-0.4f,0.0f
rectColorBuffer };
 float[] pentacle = new float[]{
   0.4f,0.4f,0.0f,
   -0.2f,0.3f,0.0f,
   0.5f,0.0f,0f,
   -0.4f,0.0f,0f
   -0.1f,-0.3f,0f
 };
 FloatBuffer triangleDataBuffer;
 IntBuffer triangleColorBuffer;
 FloatBuffer rectDataBuffer;
 FloatBuffer rectDataBuffer2;
 FloatBuffer pentacleBuffer;
 IntBuffer rectDataBuffer;
 public MyRenderer()
 {
  //将顶点位置数据数组包装成FloatBuffer；
  triangleDataBuffer = FloatBuffer.wrap(triangleData);
  rectDataBuffer =FloatBuffer.wrap(rectData);
  rectDataBuffer2 =FloatBuffer.wrap(rectData2);
  pentacleBuffer = FloatBuffer.wrap(pentacle);
  //将顶点颜色数据数组包装成IntBuffer；
  triangleColorBuffer=IntBuffer.wrap(triangleColor);
  rectColorBuffer= IntBuffer.wrap(rectColor);
 };
 //关闭抗抖动
  gl.glDisable(GL10.GL_DITHER);
  //设置系对透视进行修正
  gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_FASTEST);
  gl.glClearColor(0, 0, 0, 0);
  //设置阴影平滑模式
  gl.glShadeModel(GL10.GL_SMOOTH);
  //启用深度测试
  gl.glEnable(GL10.GL_DEPTH_TEST);
  //设置深度测试的类型
  gl.glDepthFunc(GL10.GL_LEQUAL);
 }
 public void onSurfaceChanged(GL10 gl,int width,int height)
 {
  //设置3D视窗的大小和位置
  gl.glViewport(0,0,width,height);
  //将当前矩阵模式设为投影矩阵
  gl.glMatrixMode(GL10.GL_PROJECTION);
  //初始化单位矩阵
  gl.glLoadIdentity();
  //计算透视视窗的宽度、高度比
  float ratio = (float)width/height;
  //调用此方法设置透视视窗的空间大小
  gl.glFrustumf(-ratio,ratio,-1,1,1,10);
 }
 public void onDrawFrame(GL10 gl)
 {
  //清除屏幕缓存和深度缓存
  gl.glClear(GL10.GL_COLOR_BUFFER_BIT|GL10.GL_DEPTH_BUFFER_BIT);
  //启用顶点坐标数据
  gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
  //启用顶点颜色数据
  gl.glEnableClientState(GL10.GL_COLOR_ARRAY);
  //设置当前矩阵堆栈为模型堆栈
  gl.glMatrixMode(GL10.GL_MODELVIEW);
  //绘制第一个图形，重置当前的模型视图矩阵
  gl.glLoadIdentity();
  gl.glTranslatef(-0.32f, 0.35f, -1f);
  //设置顶点的位置数据
  gl.glVertexPointer(3, GL10.GL_FLOAT, 0, triangleDataBuffer);
  //设置顶点的颜色数据
  gl.glColorPointer(4, GL10.GL_FIXED, 0, triangleColorBuffer);
  //根据顶点数据绘制平面图形
  gl.glDrawArrays(GL10.GL_TRIANGLES, 0, 3);
  //绘制第二个图形
  gl.glLoadIdentity();
  gl.glTranslatef(0.6f, 0.8f, -1.5f);
  gl.glVertexPointer(3, GL10.GL_FLOAT, 0, rectDataBuffer);
  gl.glColorPointer(4, GL10.GL_FIXED, 0, rectColorBuffer);
  gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP,0,4);
  //绘制第三个图形
  gl.glLoadIdentity();
  gl.glTranslatef(-0.4f, -0.5f, -1.5f);
  gl.glVertexPointer(3,GL10.GL_FLOAT, 0, rectDataBuffer2);
  gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP,0,4);
  //
  gl.glLoadIdentity();
  gl.glTranslatef(0.4f, -0.5f, -1.5f);
  //设置使用纯色填充
  gl.glColor4f(1.0f,0.2f,0.2f,0.0f);
  gl.glDisableClientState(GL10.GL_COLOR_ARRAY);
  gl.glVertexPointer(3, GL10.GL_FLOAT, 0,penTacleBuffer);
  gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP,0,5);
  //绘制结束
  gl.glFinish();
  gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
 }
}

public void Polygon extends Activity
{
 public void onCreate(Bundle savedInstanceState)
 {
  super.onCreate(savedInstanceState);
  //创建一个GLSurfaceView，用于显示OpenGL绘制的图形
  GLSurfaceView glView = new GLSurfaceView(this);
  //创建GLSurfaceView的内容绘制器
  MyRenderer myRender = new MyRenderer();
  //为GLSurfaceView设置绘制器
  glView.setRenderer(myRender);
  setContentView(glView);
 }
}