G11_C5

Understanding and creating the game loop

Activity Flow	Slide No.	Topic	Time
TA	4-7	Quiz	1 min
	8-9	Revision	2 min
	10-23	While loop	3 min
	24-29	Events	3 min
SA	30-37	Game loop -Coding	15
Wrap - Up	38-41	Quiz	1 min
SA	42	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

Prerequisites

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.

3. Spyder IDE.

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?

Revision

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 Daisy 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?

TA1 Template

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

Teacher Activity 1

TA1 Solution

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

TA2 Template

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

Teacher Activity 2

TA2 Solution

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!

Student Activity 1

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.

SA1 Template

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

SA1 Solution

Let's create the game loop now!

Student Activity 2

Hints:

Create the "carryOn" variable and set it to "True".
Begin a "while" loop by checking the state of 'carryOn'.
Run a "for" loop to check each "event" after getting the events queue.
If the event is 'QUIT' then change the value of 'carryOn' to "False" and call the "pygame.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()

SA2 Solution

Student Activity 3

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)

SA3 Solution

Additional Activities>>

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

Student Additional Activity 1

Hints:

Create a variable "num" and set it to value 1.
Create a "while" loop and check if num is less than 50.
Print the value of num.
Increment num by 1

Print the numbers 1 to 50 using "while" loop.

SAA1 Template

Quiz>>

num=1
while num<50:
  print(num)
  num+=1

SAA1:Solution

SAA1 Solution

Student Additional Activity 2

Hints:

Create a variable "num" and set it to value 1.
Create a "while" loop and check if num is less than 50
If num is even, print the value of num.
Increment num by 1

Print all even numbers between 1 to 50 using "while" loop.

SAA2 Template

Quiz>>

num=1
while num<50:
  if num%2==0:
  	print(num)
  num+=1

SAA2:Solution

SAA2 Solution

Links Table

Activity	Activity Name	Link
TEACHER ACTIVITY 1	While loop
TEACHER ACTIVITY 2	For loop encoding using while
TEACHER ACTIVITY 1 SOLUTION	Solution of TA1
TEACHER ACTIVITY 2 SOLUTION	Solution of TA2
STUDENT ACTIVITY 1	Game loop creation-I
STUDENT ACTIVITY 2	Game loop creation-II
STUDENT ACTIVITY 3	Game loop creation-III
TEACHER REFERENCE: STUDENT ACTIVITY 1 SOLUTION	Solution of SA1
TEACHER REFERENCE: STUDENT ACTIVITY 2 SOLUTION	Solution of SA2
TEACHER REFERENCE: STUDENT ACTIVITY 3 SOLUTION	Solution of SA3
STUDENT ADDITIONAL ACTIVITY 1	Printing Natural Numbers
STUDENT ADDITIONAL ACTIVITY 2	Printing Even Numbers
TEACHER REFERENCE: STUDENT ADDITIONAL ACTIVITY 1 SOLUTION	Solution of SAA1
TEACHER REFERENCE: STUDENT ADDITIONAL ACTIVITY 2 SOLUTION	Solution of SAA2

Understanding and creating the game loop

Class Structure

Preparation and Reference

Prerequisites

FOR TEACHER

FOR STUDENTS

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?

Revision

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?

Teacher Activity 1

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.

Teacher Activity 2

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!!

Student Activity 1

Student Activity 2

Student Activity 3

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

Student Additional Activity 1

SAA1:Solution

Student Additional Activity 2

SAA2:Solution

Links Table

G11_C5

More from Sanjukta Bhattacharya