“你好，JOGL - Java與OpenGl的綁定”是網絡上比較容易找到的關於JOGL的入門文章，其英文版“Hello JOGL, Introducing Java Bindings for OpenGL”最早發佈於2005年2月，隨着JOGL新版本的發佈，其中的一些代碼無法在新的JOGL中正確的編譯，我在學習的過程中對該文中的代碼進行修改，從而在新版JOGL中可以正常編譯和運行。
文中代碼中需要進行的主要變化包括：
- 模塊的打包已改爲javax.media.opengl.*；
- GLEventListener的接口參數drawable類型改爲GLAutoDrawable；
- GLCanvas對象已經可以通過構造函數直接創建；
- GLU對象可以通過構造函數直接創建，不必從GLAutoDrawable中獲取；
- GLU類在javax.media.opengl.glu模塊中定義，因此需要單獨import；
修改後的代碼在JOGL 1.1.1環境下正常編譯與運行。
相關經過修改的代碼如下：
helloJogl.java：
import javax.media.opengl.*;
public class helloJogl {
public static void main (String args[]) {
try {
System.loadLibrary("jogl"); System.out.println("Hello World! (The native libraries are installed.)");
} catch (Exception e) { System.out.println(e); } }
}
SimpleJoglApp.java
import java.awt.*;import java.awt.event.*;import javax.swing.*;import javax.media.opengl.*;/** * This is a basic JOGL app. Feel free to * reuse this code or modify it. */public class SimpleJoglApp extends JFrame { public static void main(String[] args) { final SimpleJoglApp app = new SimpleJoglApp(); // show what we've done SwingUtilities.invokeLater ( new Runnable() { public void run() { app.setVisible(true); } } ); } public SimpleJoglApp() { //set the JFrame title super("Simple JOGL Application"); //kill the process when the JFrame is closed setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //only three JOGL lines of code ... and here they are GLCapabilities glcaps = new GLCapabilities(); GLCanvas glcanvas = new GLCanvas(glcaps); //GLDrawableFactory.getFactory().createGLCanvas(glcaps); glcanvas.addGLEventListener(new SimpleGLEventListener()); //add the GLCanvas just like we would any Component getContentPane().add(glcanvas, BorderLayout.CENTER); setSize(500, 300); //center the JFrame on the screen centerWindow(this); } public void centerWindow(Component frame) { Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize(); Dimension frameSize = frame.getSize(); if (frameSize.width > screenSize.width ) frameSize.width = screenSize.width; if (frameSize.height > screenSize.height) frameSize.height = screenSize.height; // Frame.setLocation (// (screenSize.width - frameSize.width ) >> 1,// (screenSize.height - frameSize.height) >> 1// ); }}
SimpleGLEventListener.java
import java.awt.*;import java.awt.event.*;import javax.media.opengl.*;/*** For our purposes only two of the * GLEventListeners matter. Those would * be init() and display(). * 爲了達到我們的目的，GLEventListener中只有兩個方法有用。 * 它們是init()和display()。 */public class SimpleGLEventListener implements GLEventListener{ /** * Take care of initialization here. * 注意這裏的初始化。 */ public void init(GLAutoDrawable drawable) { } /** * Take care of drawing here. * 注意這裏的繪圖。 */ public void display(GLAutoDrawable drawable) { } /** * Called when the GLDrawable (GLCanvas * or GLJPanel) has changed in size. We * won't need this, but you may eventually * need it -- just not yet. * 當GLDrawable（GLCanvas或GLJPanel）大小改變時被調用。 * 我們不需要它，但你可能最後會用到——雖然現在並不需要。 */ public void reshape( GLAutoDrawable drawable, int x, int y, int width, int height) {} /** * If the display depth is changed while the * program is running this method is called. * Nowadays this doesn't happen much, unless * a programmer has his program do it. * 當程序運行時顯示深度被改變的時候此方法被調用。 * 現在這種事發生得不多，除非程序裏面觸發此事。 */ public void displayChanged( GLAutoDrawable drawable, boolean modeChanged, boolean deviceChanged) {}} SecondJoglApp.java
import java.awt.*;import java.awt.event.*;import javax.swing.*;import javax.media.opengl.*;/* * this is a basic JOGL app, feel free * to reuse this code or mordify it. */ public class SecondJoglApp extends JFrame { public static void main(String[] args) { final SecondJoglApp app = new SecondJoglApp(); // show what we've done SwingUtilities.invokeLater ( new Runnable() { public void run() { app.setVisible(true); } } ); } public SecondJoglApp() { // set the frame title super("Second JOGL Application"); // kill the process when the JFrame is closed setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // only three JOGL lines of code ... and here they are GLCapabilities glaps = new GLCapabilities(); GLCanvas glcanvas = new GLCanvas(glaps); glcanvas.addGLEventListener(new SecondGLEventListener()); // add the GLCanvas just like we would any component getContentPane().add(glcanvas, BorderLayout.CENTER); setSize(500, 300); // center the JFrame on the screen centerWindow(this); } public void centerWindow(Component Frame) { Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize(); Dimension frameSize = Frame.getSize(); if (frameSize.width > screenSize.width) frameSize.width = screenSize.width; if (frameSize.height > screenSize.height) frameSize.height = screenSize.height; Frame.setLocation ( (screenSize.width - frameSize.width) >> 1, (screenSize.height - frameSize.height) >> 1); }}
SecondGLEventListener.java
import javax.media.opengl.*;import javax.media.opengl.glu.*;/* * for our purposes only tow of the GLEventListeners matter. * those would be init() and display(). */public class SecondGLEventListener implements GLEventListener { /* * take care of initialization here. */ public void init (GLAutoDrawable gld) { GL gl = gld.getGL(); GLU glu = new GLU(); gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f); gl.glViewport(0, 0, 500, 300); gl.glMatrixMode(GL.GL_PROJECTION); gl.glLoadIdentity(); glu.gluOrtho2D(0.0, 500.0f, 0.0, 300.0f); } /* * take care of drawing here */ public void display(GLAutoDrawable drawable) { float red = 0.0f; float green = 0.0f; float blue = 0.0f; GL gl = drawable.getGL(); gl.glClear(GL.GL_COLOR_BUFFER_BIT); gl.glPointSize(5.0f); for (int i=0; i<50; i++) { red -= .09f; green -= .12f; blue -= .15f; if (red < 0.15) red = 1.0f; if (green < 0.15) green = 1.0f; if (blue < 0.15) blue = 1.0f; gl.glColor3f(red, green, blue); gl.glBegin(GL.GL_POINTS); gl.glVertex2i(i*10, 150); gl.glEnd(); } } public void reshape( GLAutoDrawable drawable, int x, int y, int width, int height ) {} public void displayChanged( GLAutoDrawable drawable, boolean modeChanged, boolean deviceChanged ) {}}
參考資料：
1．“你好，JOGL - Java與OpenGl的綁定”，
http://java.ccidnet.com/art/297/20060320/483789_1.html；
2．“Hello JOGL, Introducing Java Bindings for OpenGL”來源於
http://www.javaworld.com/javaworld/jw-02-2005/jw-0221-jogl.html
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