opengl开发----1.opengles的helloworld

参考,这是一位德国人Martin写的文章,年代比较久远了.但是入门还是比较好的
1. 工程的建立
eclipse --> 新建一项目  com.example.gldemo
SDK 都选API 19: android 4.4 (KitKat)  
2. 代码分析
MainActivity.java

package com.example.gldemo;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends Activity {
    private VortexView _vortexView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        _vortexView = new VortexView(this);    -->使用opengl的view
        setContentView(_vortexView);
        //setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

VortexView.java

package com.example.gldemo;

import android.content.Context;
import android.opengl.GLSurfaceView;
import android.view.MotionEvent;

public class VortexView extends GLSurfaceView{    -->VortexView继承了GLSurfaceView
    private static final String LOG_TAG="VortexView";
    private VortexRenderer _renderer;
    public VortexView (Context context){
        super(context);
        _renderer = new VortexRenderer();    -->使用opengl的view
        setRenderer(_renderer);              -->Renderer负责OpenGL call来render一个帧
    }

    public boolean onTouchEvent(final MotionEvent event){
        queueEvent(new Runnable(){
            public void run(){
                _renderer.setColor(event.getX()/getWidth(),
                                 event.getY()/getHeight(), 1.0f);
            }
        });
        return true;
    }
}

VortexRenderer.java

package com.example.gldemo;

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

import android.opengl.GLSurfaceView;

public class VortexRenderer implements GLSurfaceView.Renderer {
    private static final String LOG_TAG="VortexRenderer";
    private float _red = 0.9f;
    private float _green = 0.9f;
    private float _blue = 0.9f;

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onSurfaceChanged(GL10 gl, int w, int h){
        gl.glViewport(0, 0, w, h);
    }

    @Override
    public void onDrawFrame(GL10 gl ){
        gl.glClearColor(_red, _green, _blue, 1.0f);     -->用定义的rgb来设设置背景色
        gl.glClear(GL10.GL_COLOR_BUFFER_BIT);           -->清空buffer
    }
    public void setColor(float r, float g, float b) {   -->自己写的一个方法,来改变rgb颜色
        _red = r;                                       -->这样在onDrawFreme调用后就会在屏幕上显示出来
        _green = g;
        _blue = b;
    }

}

在render中实现3个方法:
onSurfaceCreated()  --> 在surface创建后调用
onSurfaceChanged() --> 在surface发生改变后调用,如从竖屏切换到横屏时
onDrawFrame()        --> 当调用一个画图方法的时候调用
3. 运行代码后,在屏幕的不同位置点击,屏幕会显示不同的颜色
glDemo.rar(下载后不用改名)