G11_C5

Understanding and creating the game loop

Activity Flow	Slide No.	Topic	Time
TA	3	Ice-breaker	1 min
	5-10	Programming Intro	2 min
	11-16	Object Oriented Programming	3 min
	17-22	Introduction to Python + Spyder + Pygame	3 min
	23-28	TA - Coding	15
SA	29-31	SA	5 min
Wrap - Up	32-36	Quiz	1 min
	38	Additional Activity	5 min

Slide No.	Topic
11	Random number code
23-25	Basic pygame code
31-32	Making rectangles
36	SA Code- Creating enemy rect.
45	Additional Activity- Code

Class Structure

Preparation and Reference

Pre-Requisites

FOR TEACHER

FOR STUDENTS

1. Computer with an Internet connection.

2. The latest browser installed.

3. Spyder IDE.

4. Projector to present the screen.

1. Computer with an Internet connection.

2. The latest browser installed.

(WARM-UP QUIZ)

x=5
for i in range(3):
  x*=5
  print(x)

25
125
625

Try to predict the output for the following code:

C

Q.1

A

B

C

loop begins

x=5

loop ends

printed

loop no.	i is:	x becomes:
1	0	5*5=25
2	1	25*5=125
3	2	125*5=625

x=5
for i in range(3):
  x*=5
  print(x)

Try to predict the output for the following code:

A

Q.2

A

B

C

loop begins

x=5

loop ends

x=625

(printed)

loop no.	i is:	x becomes:
1	0	5*5=25
2	1	25*5=125
3	2	125*5=625

Do you remember the problem we encountered in brick-ball collisions?

Let's revise

Do you remember how we created the brick wall in the previous class?

The mystery of the brick reappearance

What am I missing?

import pygame
pygame.init() 
screen = pygame.display.set_mode((600, 600))
pygame.display.set_caption("Breakout Game")
paddle=pygame.Rect(300,500,60,10)
ball=pygame.Rect(200,250,10,10)
ballx=-1
bally=-1
paddlex=2
carryOn = True
while carryOn:
    for event in pygame.event.get(): 
            if event.type == pygame.QUIT: 
                  carryOn = False            
    screen.fill((36,90,190))
    if event.type == pygame.KEYDOWN:
        if event.key == pygame.K_RIGHT:
            if paddle.x<540: 
                paddle.x+=paddlex
        if event.key == pygame.K_LEFT:
            if paddle.x>0:
                paddle.x-=paddlex
           
    pygame.draw.rect(screen,(0,176,240),paddle)
    ball.x=ball.x+ballx
    ball.y=ball.y+bally
    if ball.x>=590:
        ballx=-ballx
    if ball.x<=10:
        ballx=-ballx
    if ball.y>=590:
        bally=-bally
    if ball.y<=10:
        bally=-bally
    if paddle.collidepoint(ball.x,ball.y):
        bally=-bally
   
    pygame.draw.rect(screen,(255,255,255) ,ball)
    
    for i in range(7):
     brick=pygame.Rect(10 + i* 100,60,80,30)
     pygame.draw.rect(screen,(255,0,0),brick)
    for i in range(7):
     brick=pygame.Rect(10 + i* 100,60,80,30)
     pygame.draw.rect(screen,(255,100,0),brick)
     if brick.collidepoint(ball.x,ball.y):   
      pygame.draw.rect(screen,(36,90,190),brick)
      
    
    pygame.display.flip()
pygame.quit()

Unexplored code!

What going on here?

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

Some déjà vu !

We have learned this already!

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

Something new!

This looks new!!

Is friend busy?

YES

NO! She is coming this way!!

Let's keep decorating

Continuous decision making

while(condition):

Execute

colon

tab

space

maria_busy=True
while maria_busy:
  print("Keep decorating!")
  maria_busy=False
print("Get ready to surprise!")

How does the computer do this?

maria_busy=True
while maria_busy:
  print("Keep decorating!")
  maria_busy=False
print("Get ready to surprise!")

It's getting clearer!!

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

Flow of the while loop in the game

for i in range(5):
  #Execute task


i=0	Execute task once
1	Execute once more
2	Execute again
...	...
4	Execute for the 5th time

Creating a while loop

Let us try to recreate the output of this for loop using a while loop

i=0
while i<5:
  print(i)
  i=i+1

GREAT!

Some more new things!!

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

What is an event?

Let me press a key!!

Wow!! the paddle moved!

Let's recall

Key is pressed

Mouse is clicked

Perform some tasks

pygame.event

Events in pygame

How does the computer understand user has clicked / pressed something?

pygame.event.get()

Queue of events

Event 1

Event 2

Event 3

Getting Events

But how do i know what exactly the user did??

Queue of events

for

loop!!

for event in pygame.event.get()

event.type

pygame.QUIT

pygame.KEYDOWN

Determining the type of the event

Event 1

Event 2

Event 3

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

Now I am an expert!

Some more new things!!

Let us begin creating the game from scratch now!

Try to code!

Hints:

Import pygame
Initialize pygame
Create the screen variable [Hint:Use the 'display.set_mode' function and pass the screen length and breadth as parameter]
Create the ball and paddle rectangle objects.
Create ballx, bally, paddlex.

import pygame
pygame.init() 
screen = pygame.display.set_mode((600,600))
paddle=pygame.Rect(300,500,60,10)
ball=pygame.Rect(200,250,10,10)
ballx=1
bally=1
paddlex=2

Let create the game loop now!

Creating the game loop

Hints:

Create the 'carryOn' variable and set it to True.
Begin a while loop checking state of 'carryOn'
Run a for loop to check each event after getting the event.
if event is QUIT then change value of 'carryOn' to False and call the pyjama.quit()function.

import pygame
pygame.init() 
screen = pygame.display.set_mode((600,600))
paddle=pygame.Rect(300,500,60,10)
ball=pygame.Rect(200,250,10,10)
ballx=1
bally=1
paddlex=2

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

Filling the screen

Hints:

Use the .fill( ) function on the screen variable within the while loop.
Choose an RGB color code.

Now fill the screen with a color of your choice

import pygame
pygame.init() 
screen = pygame.display.set_mode((600,600))
paddle=pygame.Rect(300,500,60,10)
ball=pygame.Rect(200,250,10,10)
ballx=1
bally=1
paddlex=2

carryOn = True
while carryOn:
    for event in pygame.event.get(): 
            if event.type == pygame.QUIT: 
                  carryOn = False 
    screen.fill(0,176,240)

x=10
while False:
  x=x+100
print(x)

Error

Try to predict the output for the following code:

C

Q.1

A

B

C

While loop set to false by default

x=10

10 is printed

No Change in x

x=5
i=0
while i<3:
  x*=5
  print(x)
  i=i+1

25
125
625

Try to predict the output for the following code:

C

Q.2

A

B

C

loop begins

x=5

loop ends

printed

loop no.	i is:	x becomes:
1	0	5*5=25
2	0+1=1	25*5=125
3	1+1=2	125*5=625

Try to code

Hints:

Import pygame
Initiate pygame
Create the game loop
Fill the screen
Draw the required objects
Update object positions if required.

Let's create a game

Activity	Activity Name	Link
Teacher Activity 1	Space Invader game demo	https://replit.com/@ShubhamVerma9/DemoSpaceInvaders#main.py
Teacher Activity 2	Space Invader 0.5	https://bit.ly/3uePVRU
Student Activity 1	Space Invader -0	https://bit.ly/3va7RhO
Additional Activity 1- Solution	Space Invader 0.5 + AA	https://bit.ly/2SeaAZ2

Understanding and creating the game loop

Class Structure

Preparation and Reference

Pre-Requisites

FOR TEACHER

FOR STUDENTS

(WARM-UP QUIZ)

Try to predict the output for the following code:

C

Q.1

A

B

C

Try to predict the output for the following code:

A

Q.2

A

B

C

Do you remember the problem we encountered in brick-ball collisions?

Let's revise

Do you remember how we created the brick wall in the previous class?

The mystery of the brick reappearance

What am I missing?

Unexplored code!

What going on here?

Some déjà vu !

We have learned this already!

Something new!

This looks new!!

Continuous decision making

How does the computer do this?

It's getting clearer!!

Flow of the while loop in the game

Creating a while loop

Let us try to recreate the output of this for loop using a while loop

GREAT!

Some more new things!!

What is an event?

Let's recall

Events in pygame

Getting Events

Determining the type of the event

Some more new things!!

Try to code!

Creating the game loop

Filling the screen

Try to predict the output for the following code:

C

Q.1

A

B

C

Try to predict the output for the following code:

C

Q.2

A

B

C

Try to code

Links Table