好的，所以我一直试图让这个球自然反弹几个星期，现在看起来似乎并不合适。该程序应允许用户输入一定量的重力，然后根据该量使球反弹。它适用于前几次反弹，但停球是问题所在。我必须故意将其运动设置为0，否则它将无限地反弹到位但不会在x轴上移动。这个问题只发生在重力设置为15，其他数量和事情真的变坏的时候。球会自然弹跳，但永远在x轴上滚动。我从来没有上过物理课，所以问题可能出在物理代码中。有人知道问题在哪里吗？
这是代码我的代码 -
import java.applet.Applet;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.util.Random;
import javax.swing.JOptionPane;
//key stuff
import java.awt.KeyEventDispatcher;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyEvent;
public class StartingPoint extends Applet implements Runnable{
//key press
private static boolean wPressed = false;
public static boolean isWPressed() {
synchronized (StartingPoint.class) {
return wPressed;
}
}
//for position of circle
int x = 0;
int y= 0;
//for position change
double dx = 2;
double dy = 2;
//for circle size
int rad = 11;
//image for update()
private Image i;
private Graphics gTwo;
//Physics
double grav = 15;
double engloss= .65;
double tc = .2;
double friction = .9;
@Override
public void init() {
// sets window size
setSize(800,600);
}
@Override
public void start() {
//"this" refers to the implemented run method
Thread threadOne = new Thread(this);
//this goes to run()
threadOne.start();
}
@Override
public void run() {
String input = JOptionPane.showInputDialog( "How much gravity?" );
grav= Double.parseDouble(input);
// sets frame rate
while (true){
//makes sure it doesn't go off screen x wise
//right side
if (x + dx > this.getWidth() - rad -1){
x= this.getWidth() -rad -1; //blocks it from moving past boundary
dx = -dx; //Reveres it
}
//left side
else if (x + dx < 1 + rad){
x= 1+rad; //ball bounces from the center so it adjusts for this by adding one and rad to pad out the radius of the ball plus one pixel.
dx = -dx; //Inverters its movement so it will bounce
}
//makes the ball move
else{
x += dx; // if its not hitting anything it keeps adding dx to x so it will move.
}
//friction
if(y == this.getHeight()-rad -1){
dx *= friction; //every time the ball hits the bottom dx is decreased by 10% by multiplying by .9
//Keeps it from micro bouncing for ever
if (Math.abs(dy) < 4){ // if the speed of y (dy) is less than .4 it is set to 0
dy= 0;
}
/**if (Math.abs(dx) < .00000000000000000001){ // if the speed of x (dx) is less than .00000000000000000001 it is set to 0, this value doesn't seem to matter
dx = 0;
}**/
}
//makes sure it doesn't go off screen y wise
//down
if (y > this.getHeight() - rad -0){ // TODO Check how getHieght is measured.
y= this.getHeight() -rad -0;
//makes ball loose speed.
dy *= engloss;
dy = -dy;
}
else {
//velocity
// tc makes grav smaller. Total of which is added to dy. To increase velocity as the ball goes down.
dy += grav *tc;
//gravity
//new dy is decreased by tc + .5 multiplied by gravity and tc squared. This makes the ball bounce lower every time based on its speed
y += dy*tc + .5*grav*tc*tc;
}
//frame rate
repaint();
try {
Thread.sleep(17);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
//end frame rate
}
@Override
public void stop() {
}
@Override
public void destroy() {
}
@Override
public void update(Graphics g) {
//keeps it from flickering... don't know how though
if(i == null){
i = createImage(this.getSize().width, this.getSize().height);
gTwo = i.getGraphics();
}
gTwo.setColor(getBackground());
gTwo.fillRect(0, 0, this.getSize().width, this.getSize().height);
gTwo.setColor(getForeground());
paint(gTwo);
g.drawImage(i, 0, 0, this);
//do some thing with setDoubleBuffered
}
@Override
public void paint(Graphics g) {
g.setColor(Color.BLUE);
g.fillOval(x-rad, y-rad, rad*2, rad*2);
}
}