Android基于OpenGL在GLSurfaceView上绘制三角形及使用投影和相机视图方法示例

public class Triangle {
  public Triangle()
  {
     float triangleCoords[] = {
          // X, Y, Z 这是一个等边三角形
          -0.5f, -0.25f, 0,
           0.5f, -0.25f, 0,
           0.0f, 0.559016994f, 0
        };
        // 初始化三角形的顶点缓存
        ByteBuffer vbb = ByteBuffer.allocateDirect(
            // (# of coordinate values * 4 bytes per float)
            triangleCoords.length * 4);
        vbb.order(ByteOrder.nativeOrder());// 使用设备硬件本身的字节序
        triangleVB = vbb.asFloatBuffer(); // 从ByteBuffer中创建一个浮点缓存
        triangleVB.put(triangleCoords); // 向浮点缓存中添加顶点坐标
        triangleVB.position(0); // 使缓存读第一个坐标
  }
  public void draw(GL10 gl)
  {
    gl.glColor4f(0.63671875f, 0.76953125f, 0.22265625f, 0.0f); //设置当前颜色
    gl.glVertexPointer(3, GL10.GL_FLOAT, 0, triangleVB);//设置顶点
    gl.glDrawArrays(GL10.GL_TRIANGLES, 0, 3);//绘制三角形
  }
  private FloatBuffer triangleVB;
}

public myGLRenderer()
{
    mTriangle = new Triangle();
}

@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
    // TODO Auto-generated method stub
    gl.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
    gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
}

@Override
public void onDrawFrame(GL10 gl) {
    // TODO Auto-generated method stub
    gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
    mTriangle.draw(gl);
}

@Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
    // TODO Auto-generated method stub
    gl.glViewport(0, 0, width, height);
    float ratio = (float) width / height;
    gl.glMatrixMode(GL10.GL_PROJECTION); // 设置当前矩阵为投影矩阵
    gl.glLoadIdentity(); // 重置矩阵为初始值
    gl.glFrustumf(-ratio, ratio, -1, 1, 3, 7); // 根据长宽比设置投影矩阵
}

@Override
public void onDrawFrame(GL10 gl) {
  // TODO Auto-generated method stub
    gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
    // 设置当前矩阵为模型视图模式
    gl.glMatrixMode(GL10.GL_MODELVIEW);
    gl.glLoadIdentity();  // reset the matrix to its default state
    // 设置视点
    GLU.gluLookAt(gl, 0, 0, -5, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
    mTriangle.draw(gl);
}