OpenGL学习（1）基本概述

OpenGL学习（1）基本概述

(1)重写Rendar（渲染器）， 重写三个方法：

        a、onSurfaceCreated(GL10 gl, EGLConfig config);
        b、onSurfaceChanged(GL10 gl, int width, int height); 
        c、 onDrawFrame(GL10 gl);

package com.example.mychapter2;

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

import android.opengl.GLU;
import android.opengl.GLSurfaceView.Renderer;

public class GLRender implements Renderer
{
    public void onDrawFrame(GL10 gl)
    {
        // TODO Auto-generated method stub

        // 首先清理屏幕
        gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

        // 设置模型视图矩阵
        gl.glMatrixMode(GL10.GL_MODELVIEW);

        // 重置矩阵
        gl.glLoadIdentity();

        // 视点变换
        GLU.gluLookAt(gl, 0, 0, 3, 0, 0, 0, 0, 1, 0);

        // ...

    }

    public void onSurfaceChanged(GL10 gl, int width, int height)
    {
        // TODO Auto-generated method stub

        float ratio = (float) width / height;

        // 设置视口(OpenGL场景的大小)
        gl.glViewport(0, 0, width, height);

        // 设置投影矩阵为透视投影
        gl.glMatrixMode(GL10.GL_PROJECTION);

        // 重置投影矩阵（置为单位矩阵）
        gl.glLoadIdentity();

        // 创建一个透视投影矩阵（设置视口大小）
        gl.glFrustumf(-ratio, ratio, -1, 1, 1, 10);
    }

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

        // 告诉系统需要对透视进行修正
        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);

        // 设置清理屏幕的颜色
        gl.glClearColor(0, 0, 0, 1);

        // 启用深度缓存
        gl.glEnable(GL10.GL_DEPTH_TEST);
    }

}

(2)创建一个GLSurfaceView

  (a)创建一个GLSurfaceView实例mGLSurfaceView，
(b)设置渲染器mGLSurfaceView.setRenderer(Render);

package com.example.mychapter2;

import android.app.Activity;
import android.opengl.GLSurfaceView;
import android.os.Bundle;

public class ChapterMain extends Activity
{
    private GLSurfaceView mGLSurfaceView;

    /** Called when the activity is first created. */
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        // 实例化GLSurfaceView
        mGLSurfaceView = new GLSurfaceView(this);

        // 设置渲染器
        mGLSurfaceView.setRenderer(new GLRender());

        setContentView(mGLSurfaceView);
    }

    protected void onResume()
    {
        super.onResume();
        mGLSurfaceView.onResume();
    }


    protected void onPause()
    {
        super.onPause();
        mGLSurfaceView.onPause();
    }
}