## bat_ball_collision_detection.py

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## Code Snippet

``````
"""
NOTE OF POSITIONS

ball pos [0] Top left coordinate x1
ball pos [1] Top left coordinate y1
ball pos [2] Bottom right coordinate x2
ball pos [3] Bottom right coordinate y2

bat pos [0] Top left coordinate x1
bat pos [1] Top left coordinate y1
bat pos [2] Bottom right coordinate x2
bat pos [3] Bottom right coordinate y2

"""

from tkinter import *
import random
import time

class Ball:
def __init__(self,canvas,bat,color):  #change the __init__function in class Ball to pass in the bat object as a parameter
self.canvas=canvas
self.bat=bat #here we assign the bat parameter to the object variable bat
self.id=canvas.create_oval(30,30,50,50,fill=color)
self.canvas.move(self.id,100,200)
starting_position=[-3,-2,-1,1,2,3]
random.shuffle(starting_position)
self.x = starting_position[0]
self.y = -3
self.canvas_height=self.canvas.winfo_height()
self.canvas_width=self.canvas.winfo_width()

#Create the hit_bat function
def hit_bat(self,pos):
bat_pos=self.canvas.coords(self.bat.id) #retrieve the coordinates of the bat position - note the ball coordinates are being passed
if pos[2] >=bat_pos[0] and pos[0] <=bat_pos[2]: #if the right side of the ball (that is the x right hand coordinate) is greater than the left side of the bat, AND the left side of the ball is less than the right side of the bat ....move etc
if pos[3]>=bat_pos[1] and pos[3] <= bat_pos[3]: #if the bottom of the ball (pos[3]) is between the paddle's top [bat pos[1]) and bottom (pos[3])
return True
return False

def draw(self):
self.canvas.move(self.id,self.x,self.y)
pos=self.canvas.coords(self.id)
if pos[1] <=0:
self.y=6
if pos[3] >=self.canvas_height:
self.y=-6
#Call the hit_bat function
if self.hit_bat(pos) ==True: #if the hit_bat function returns a value of True, the direction of the ball is changed
self.y=-6 #if the ball hits the bat, then send the ball flying up at a rate of -6 (higher the number the faster the fly!)
if pos[0] <=0:
self.x=6
if pos[2]>=self.canvas_width:
self.x=-6

class Pongbat():
def __init__(self,canvas,color):
self.canvas=canvas
self.id=canvas.create_rectangle(0,0,100,10,fill=color)
self.canvas.move(self.id,200,300)
self.x=0
self.canvas_width=self.canvas.winfo_width()
self.canvas.bind_all('',self.left_turn)
self.canvas.bind_all('',self.right_turn)

def draw(self):
self.canvas.move(self.id,self.x,0)
pos=self.canvas.coords(self.id)
if pos[0]<=0:
self.x=0
if pos[2]>=self.canvas_width:
self.x=0

def left_turn(self,evt):
self.x=-10

def right_turn(self,evt):
self.x=10

def main():
tk=Tk()
tk.title("My 21st Century Pong Game")
tk.resizable(0,0)
tk.wm_attributes("-topmost",1)
canvas=Canvas(tk,bg="white",width=500,height=400,bd=0,highlightthickness=0)
canvas.pack()
tk.update()

bat1=Pongbat(canvas,'red') #this has to be created first, otherwise it will not recognise the call to the bat parameter in the next statement
ball1=Ball(canvas,bat1, 'green') #change this so that it includes the bat parameter (we included it in the ball's __init__method

while 1:
tk.update()
ball1.draw()
bat1.draw()
time.sleep(0.02)
main()

#note - an ERROR may be caused as Python is complaining about breaking out of the while loop when the window is closed - you can ignore that for now (or a fix is provied in the solutions section for those who are interested"""

``````