Api Demo - .graphics(24)>>TouchRotateActivity

package com.example.android.apis.graphics;

import javax.microedition.khronos.egl.EGL10;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

import android.app.Activity;
import android.content.Context;
import android.opengl.GLSurfaceView;
import android.os.Bundle;
import android.view.MotionEvent;

public class TouchRotateActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Create our Preview view and set it as the content of our
        // Activity
        mGLSurfaceView = new TouchSurfaceView(this);
        setContentView(mGLSurfaceView);
        mGLSurfaceView.requestFocus();
        mGLSurfaceView.setFocusableInTouchMode(true);
    }

    @Override
    protected void onResume() {
        // Ideally a game should implement onResume() and onPause()
        // to take appropriate action when the activity looses focus
        super.onResume();
        mGLSurfaceView.onResume();
    }

    @Override
    protected void onPause() {
        // Ideally a game should implement onResume() and onPause()
        // to take appropriate action when the activity looses focus
        super.onPause();
        mGLSurfaceView.onPause();
    }

    private GLSurfaceView mGLSurfaceView;
}

/**
 * Implement a simple rotation control.
 *
 */
class TouchSurfaceView extends GLSurfaceView {

    public TouchSurfaceView(Context context) {
        super(context);
        mRenderer = new CubeRenderer();
        setRenderer(mRenderer);
        setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);//设置渲染模式
    }

    @Override public boolean onTrackballEvent(MotionEvent e) {//轨迹球监听
        mRenderer.mAngleX += e.getX() * TRACKBALL_SCALE_FACTOR;
        mRenderer.mAngleY += e.getY() * TRACKBALL_SCALE_FACTOR;
        requestRender();
        return true;
    }

    @Override public boolean onTouchEvent(MotionEvent e) {//触摸监听
        float x = e.getX();
        float y = e.getY();
        switch (e.getAction()) {
        case MotionEvent.ACTION_MOVE:
            float dx = x - mPreviousX;
            float dy = y - mPreviousY;
            mRenderer.mAngleX += dx * TOUCH_SCALE_FACTOR; //绕X轴旋转。
            mRenderer.mAngleY += dy * TOUCH_SCALE_FACTOR;//绕Y轴旋转
            requestRender();//选项渲染
        }
        mPreviousX = x;
        mPreviousY = y;
        return true;
    }

    /**
     * Render a cube.
     */
    private class CubeRenderer implements GLSurfaceView.Renderer {
        public CubeRenderer() {
            mCube = new Cube();//新建立方体
        }

        public void onDrawFrame(GL10 gl) {

            gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);//清楚缓存
            gl.glMatrixMode(GL10.GL_MODELVIEW);//设置模式矩阵为当前矩阵
            gl.glLoadIdentity();//复位矩阵
            gl.glTranslatef(0, 0, -3.0f);//沿Z轴方向移动
            gl.glRotatef(mAngleX, 0, 1, 0);//旋转
            gl.glRotatef(mAngleY, 1, 0, 0);

            gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);//打开顶点状态
            gl.glEnableClientState(GL10.GL_COLOR_ARRAY);//打开颜色状态。

            mCube.draw(gl);
        }

        public void onSurfaceChanged(GL10 gl, int width, int height) {
             gl.glViewport(0, 0, width, height);

             

             float ratio = (float) width / height;
             /*
              *  glMatrixMode用来转换当前是模型矩阵还是投影矩阵，操作物体时使用模型矩阵，如平移、旋转、缩放等。
              *  设置观察物体的方式时，选择投影矩阵。 
              */
             gl.glMatrixMode(GL10.GL_PROJECTION);
             gl.glLoadIdentity();
             gl.glFrustumf(-ratio, ratio, -1, 1, 1, 10);
        }

        public void onSurfaceCreated(GL10 gl, EGLConfig config) {
            /*
             * By default, OpenGL enables features that improve quality
             * but reduce performance. One might want to tweak that
             * especially on software renderer.
             */
            gl.glDisable(GL10.GL_DITHER);

            /*
             * 1.gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_FASTEST); 
             * GL_PERSPECTIVE_CORRECTION_HINT时，是指定颜色和纹理坐标的插值质量. 
             * GL_FASTEST为使用速度最快的模式. 
             * GL_NICEST为使用质量最好的模式. 
             * 还有一个GL_DONT_CARE为由驱动设备来决定. 
             */
             gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,
                     GL10.GL_FASTEST);


             gl.glClearColor(1,1,1,1);
             gl.glEnable(GL10.GL_CULL_FACE);
             gl.glShadeModel(GL10.GL_SMOOTH);
             /*
              * glShadeModel 默认GL_SMOOTH方式。 
              * GL_FLAT  单色渲染，如果设置多个颜色，只有最后一组颜色启作用 
              * GL_SMOOTH  平滑模式，每个顶点都有自己的色彩，色彩之间的过渡也比较平滑。从运行结果中能看的很明显。 
              */
             gl.glEnable(GL10.GL_DEPTH_TEST);
        }
        private Cube mCube;
        public float mAngleX;
        public float mAngleY;
    }

    private final float TOUCH_SCALE_FACTOR = 180.0f / 320;
    private final float TRACKBALL_SCALE_FACTOR = 36.0f;
    private CubeRenderer mRenderer;
    private float mPreviousX;
    private float mPreviousY;
}