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)


625
25
125
625
125

Try to predict the output for the following code:

C

Q.1

A

B

C

loop begins

x=5

loop ends

printed

printed

printed

loop no. i is: x becomes:
1 0 5*5=25
2 1 25*5=125
3 2 125*5=625 
5
x=5
for i in range(3):
  x*=5
  print(x)


625
125

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

B

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
Execute
Execute
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

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)
10
110
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
625
25
125
625
125

Try to predict the output for the following code:

C

Q.2

A

B

C

loop begins

x=5

loop ends

printed

printed

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

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Copy of G11 C5

By anjali_sharma

Source: Sanjukta Bhattacharya

Copy of G11 C5

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