我有一个简单的物理循环,它计算一个时间间隔,等待间隔通过,然后在屏幕上呈现结果。这是非常简单的代码(虽然时间可能是错误的,但这正是我试图了解的)并且当我在屏幕上移动鼠标时效果很好。
package physicssim;
import java.awt.Graphics;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class PhysicsSim extends JFrame {
private static class PhysicsObject {
public PhysicsObject(double x, double y, double v_x, double v_y) {
this.x = x;
this.y = y;
this.v_x = v_x;
this.v_y = v_y;
}
public double x;
public double y;
public double v_x;
public double v_y;
}
PhysicsObject particle;
boolean running = true;
DrawPane drawPane;
public PhysicsSim() {
particle = new PhysicsObject(10,10, .1, .2);
drawPane = new DrawPane(particle);
this.setSize(800,600);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setContentPane(drawPane);
this.setVisible(true);
}
private static class DrawPane extends JPanel {
PhysicsObject p;
public DrawPane(PhysicsObject p) {
this.p = p;
}
@Override
public void paint(Graphics g) {
super.paint(g); //To change body of generated methods, choose Tools | Templates.
g.fillOval((int)p.x, (int) p.y, 10, 10);
}
}
public void start() {
int FPS = 60;
long TIME_BETWEEN_FRAMES_NS = 1000000000/FPS;
// Initial draw
drawPane.repaint();
long lastDrawTime = System.nanoTime();
while(running) {
// Update physics
particle.x+=particle.v_x*(TIME_BETWEEN_FRAMES_NS*.0000001);
particle.y+=particle.v_y*(TIME_BETWEEN_FRAMES_NS*.0000001);
// While there is time until the next draw wait
while(TIME_BETWEEN_FRAMES_NS > (System.nanoTime()-lastDrawTime)) {
try {
Thread.sleep(1);
} catch (InterruptedException ex) {
Logger.getLogger(PhysicsSim.class.getName()).log(Level.SEVERE, null, ex);
}
}
drawPane.repaint();
long currentTime = System.nanoTime();
System.out.println(currentTime - lastDrawTime);
lastDrawTime = currentTime;
}
}
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
PhysicsSim sim = new PhysicsSim();
sim.start();
}
}
关于打印时差的最后一点只是一个完整性检查,以确保它实际上是在请求的间隔周围调用。结果相当一致,所以我不明白为什么会出现任何不稳定因素。
正如我上面提到的,如果我在屏幕上移动鼠标,一切顺利,这段代码效果很好。
如果我没有移动鼠标,那么在我开始将鼠标移到应用程序上之前,它会变得非常不稳定。
我认为这很简单,但我希望你们可以帮助我。谢谢。
答案 0 :(得分:1)
好吧,看起来我的问题是我在paint()中直接绘制了g。更换后,一切正常。
@Override
public void paint(Graphics g) {
BufferedImage img = new BufferedImage(800, 600, BufferedImage.TYPE_3BYTE_BGR);
img.getGraphics().fillOval((int) p.x, (int) p.y, 10, 10);
g.drawImage(img, 0, 0, null);
}
我正在考虑删除此代码段,因为它粗糙而可耻,但也许它会帮助其他人。快乐的编码。