J2ME 3D编程的第一个3D程序

// First3DMIDlet.java
package first3d;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class First3DMIDlet extends MIDlet 
{
private First3DCanvas displayable = new First3DCanvas();
public void startApp() 
{
Display.getDisplay(this).setCurrent(displayable);
}

public void pauseApp() {}
public void destroyApp(boolean unconditional) {}
}
// First3Dcanvas.java
package first3d;
import javax.microedition.lcdui.*;
import javax.microedition.m3g.*;
import java.util.*;
/**
* 第一个3D程序
*/
public class First3DCanvas extends Canvas implements Runnable 
{
/**World对象*/
private World myWorld = null;
/**Graphics3D对象*/
private Graphics3D g3d = Graphics3D.getInstance();
/**Camera对象*/
private Camera cam = null;
private int viewport_x;
private int viewport_y;
private int viewport_width;
private int viewport_height;
private long worldStartTime = 0;
//重绘时间
private int validity = 0;
public First3DCanvas() 
{
//启动重绘界面的线程
Thread thread = new Thread(this);
thread.start();
try 
{
//导入3D图片
myWorld = (World) Loader.load("/swerve.m3g")[0];
viewport_x = 0;
viewport_y = 0;
viewport_width = getWidth();
viewport_height = getHeight();
cam = myWorld.getActiveCamera();
//设置cam对象
float[] params = new float[4];
int type = cam.getProjection(params);
if (type != Camera.GENERIC) 
{
//calculate window aspect ratio
float waspect = viewport_width / viewport_height;
if (waspect < params[1]) 
{
float height = viewport_width / params[1];
viewport_height = (int) height;
viewport_y = (getHeight() - viewport_height) / 2;
}
else 
{
float width = viewport_height * params[1];
viewport_width = (int) width;
viewport_x = (getWidth() - viewport_width) / 2;
}
}
worldStartTime = System.currentTimeMillis();
}
catch (Exception e) {}
}
protected void paint(Graphics g) 
{
//清除背景
g.setColor(0x00);
g.fillRect(0, 0, getWidth(), getHeight());
//和3D对象绑定
g3d.bindTarget(g);
g3d.setViewport(viewport_x, viewport_y, viewport_width, viewport_height);
long startTime = System.currentTimeMillis() - worldStartTime;
validity = myWorld.animate((int)startTime);
try 
{
g3d.render(myWorld);
}
finally 
{
g3d.releaseTarget();
}
}
public void run() 
{
try
{
while(true)
{
//重绘图形
repaint(viewport_x, viewport_y, viewport_width, viewport_height);
}
}
catch(Exception e){}
}
}