Pygame bouncing bubbles

Question

I want to make a kind of screen-saver in pygame, where bubbles bounce inside the screen, and also bounce against each other. How can i do this? Below is the part for bouncing inside the screen:

import pygame
from pygame.locals import *

WIDTH=1
TV_SIZE=(800,900)

pygame.init()

CLOCK=pygame.time.Clock()
TV=pygame.display.set_mode(TV_SIZE)

class Ball(object):

    def __init__(self,pos_x,x_dir,pos_y,y_dir,color,radius):
        self.pos_x=pos_x
        self.x_dir=x_dir
        self.pos_y=pos_y
        self.y_dir=y_dir
        self.color=color
        self.radius=radius
    def move(self):
        if self.pos_x>=TV_SIZE[0]-self.radius or self.pos_x<=self.radius:
            self.x_dir=-self.x_dir
            self.pos_x+=self.x_dir
        if self.pos_y>=TV_SIZE[1]-self.radius or self.pos_y<=self.radius:
            self.y_dir=-self.y_dir
            self.pos_y+=self.y_dir
        else:
            self.pos_x+=self.x_dir
            self.pos_y+=self.y_dir
            pygame.draw.circle(TV,self.color,(self.pos_x,self.pos_y),self.radius,WIDTH)
            pygame.display.flip()

ball_1=Ball(100,5,100,5,(100,100,100),50)
ball_2=Ball(31,8,31,8,(200,200,100),30)

while True:
    for e in pygame.event.get():
        if e.type==QUIT:
            pygame.quit()

    ball_1.move()
    ball_2.move()
    TV.fill((0,0,0))

    CLOCK.tick(30)

Answer 1

This could work:

1. Check if the distance between the circle's centers. (If it is less than the sum of their radiuses, it is colliding) To find distances, find x or y pixel distances. The distance in pixels is:

   sqrt((x_dist**2) + (y_dist**2)). 
   

https://i.sstatic.net/EFR8f.png

2. If they are colliding, start the bounce. Then, you need physics. Remember: force = mass(acceleration), Total Energy = Potential Energy + Kinetic Energy. I can't really help you there, though. Just change x_dir and y_dir depending on how they collide. Experiment.

3. Feel free to ask me anything! =D