import java.nio.ByteBuffer;import java.nio.ByteOrder;import java.nio.FloatBuffer;import javax.microedition.khronos.egl.EGLConfig;import javax.microedition.khronos.opengles.GL10;import android.app.Activity;import android.opengl.GLSurfaceView;import android.opengl.GLU;import android.os.Bundle;import android.util.Log;public class MainActivity extends Activity {private final String TAG = "MainActivity";private GLSurfaceView glSurefaceView;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);glSurefaceView = new GLSurfaceView(this);glSurefaceView.setRenderer(new GLSurfaceViewRender());this.setContentView(glSurefaceView);}@Overrideprotected void onResume() {super.onResume();glSurefaceView.onResume();}@Overrideprotected void onPause() {super.onStop();glSurefaceView.onPause();}class GLSurfaceViewRender implements GLSurfaceView.Renderer {@Overridepublic void onSurfaceCreated(GL10 gl, EGLConfig config) {Log.i(TAG, "onSurfaceCreated");// 设置背景颜色gl.glClearColor(0.0f, 0f, 0f, 0.5f);// 启用顶点数组（否则glDrawArrays不起作用）gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);}@Overridepublic void onSurfaceChanged(GL10 gl, int width, int height) {Log.i(TAG, "onSurfaceChanged");// 设置输出屏幕大小gl.glViewport(0, 0, width, height);/** * Android设备屏幕通常不是正方形的，而OpenGL总是默认地将正方形坐标系投影到这一设备上，这就导致图形无法按真实比例显示。 * 要解决这一问题，我们可以使用OpenGL 的投影模式和相机视图将图形的坐标进行转换以适应不同的设备显示。 */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}private float[] mTriangleArray = {// 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 };@Overridepublic void onDrawFrame(GL10 gl) {Log.i(TAG, "onDrawFrame");// 清除屏幕和深度缓存(如果不调用该代码, 将不显示glClearColor设置的颜色)// 同样如果将该代码放到 onSurfaceCreated 中屏幕会一直闪动gl.glClear(GL10.GL_COLOR_BUFFER_BIT);/************ 启用MODELVIEW模式，并使用GLU.gluLookAt()来设置视点 ***************/// 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);/*****************************************/gl.glColor4f(1.0f, 0.0f, 0.0f, 1.0f);FloatBuffer mTriangleBuffer = BufferUtil.floatToBuffer(mTriangleArray);gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mTriangleBuffer);gl.glDrawArrays(GL10.GL_TRIANGLES, 0, 3);//gl.glLoadIdentity();// 平移 (矩阵相乘)gl.glTranslatef(-0.2f, 0.3f, 0f);}}static class BufferUtil {public static FloatBuffer mBuffer;public static FloatBuffer floatToBuffer(float[] a) {// 先初始化buffer，数组的长度*4，因为一个float占4个字节ByteBuffer mbb = ByteBuffer.allocateDirect(a.length * 4);// 数组排序用nativeOrdermbb.order(ByteOrder.nativeOrder());mBuffer = mbb.asFloatBuffer();mBuffer.put(a);mBuffer.position(0);return mBuffer;}}}
