Thread: Particle collisions...

I guess this is more of a physics question then a java question but i figured there would be a lot of smart people on this forum so here goes:

import java.applet.*;
import java.awt.*;
import javax.swing.*;
 
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.geom.*;
import java.util.concurrent.*;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.awt.event.*;
 
public class point extends Ellipse2D.Float implements MouseListener{
	double y_speed;
	double x_speed;
	int gravity = 2;
	private int d;
	private int width = Particle.WIDTH;
	private int height = Particle.HEIGHT;
	private ArrayList<point> points;
 
	// make particles randomly in screen ------V
	public point(int diameter, ArrayList<point> points){
		super((int) (Math.random() * (Particle.WIDTH - 20) + 1), (int) (Math.random() * (Particle.HEIGHT - 20) + 1), diameter, diameter);
		this.d = diameter;
		this.x_speed = (int)(Math.random()* 10 + 1);
		this.y_speed = (int)(Math.random()* 10 + 1);
		this.points=points;
	}
 
	public void move (){
		Rectangle2D r = new Rectangle2D.Float(super.x, super.y, d+1, d+1);
 
		// collision loop -------V
		for (point p : points){
			if (p != this && p.intersects(r)){
				double txspeed = x_speed;
				double tyspeed = y_speed;
                                [COLOR="Red"]// need stuff in HERE!!!![/COLOR]
 
			}
 
		}
 
		// movement stuff ------V
		if (super.x < 0){
			super.x = 0;
			x_speed = Math.abs(x_speed)/2;
		}
		else if (super.x > width - d){
			super.x = width-d;
			x_speed = -Math.abs(x_speed)/2;
		}
		if (super.y < 0){
			super.y = 0;
			y_speed = Math.abs(y_speed)/2;
		}
		else if (super.y > height - d){
			super.y = height-d;
			y_speed = -Math.abs(x_speed)/2;
		}
		if (x_speed>5){
			x_speed--;
		}
		if (x_speed<5){
			x_speed++;
		}
		if (y_speed>5){
			y_speed--;
		}
		if (y_speed<5){
			y_speed++;
		}
		y_speed+=gravity;
		y_speed*=0.99;
		x_speed*=0.99;
		super.x+=x_speed;
		super.y+=y_speed;
	}
 
	@Override
	public void mouseClicked(MouseEvent e) {
		for (point p : points){
			x_speed=x_speed+e.getX();
 
		}
 
	}
 
	@Override
	public void mouseEntered(MouseEvent e) {
 
	}
 
	@Override
	public void mouseExited(MouseEvent e) {
		// TODO Auto-generated method stub
 
	}
 
	@Override
	public void mousePressed(MouseEvent e) {
		// TODO Auto-generated method stub
 
	}
 
	@Override
	public void mouseReleased(MouseEvent e) {
		// TODO Auto-generated method stub
 
	}
}

(ignore the mouse listener stuff i was just starting to mess with it)

I've been trying to get the particles in my simulation to collide, and yes, i know several methods of detecting collisions but i figured checking for rectangle intersection would be the quickest to code. Now what I am wondering is what mathematically i can do when a collision is detected to keep the particles out of other particles rectangles in a stable manner. (no explosive flying particles going 1,000,000 miles an hour) I've been trying to figure this out for days and i feel really dumb that after watching ton of tutorials and stuff the best i have got to work is a spastic blob of dots... thanks for any help given.

ALSO if you need the other classes for some reason you can but the collision things all that really matters.

I don't really understand your question. What do you want to happen when you detect a collision? Should the particles bounce off each other? Veer off to avoid collisions? Something else?

When posting code, it should really be in the form of an SSCCE (that's a link). That means it should be runnable just by copying and pasting it into a single file and as small as possible while still demonstrating what you're talking about.