PyGame - Unit 4 PyGame Unit – Object Oriented Programming OOP

PyGame - Unit 4 Text Book for OOP Module Introduction to Computer Science Using Python and PyGame –By Paul Vincent Craven It should already be on your network drive. Easily found on the Internet: –

PyGame - Unit 4 PyGame – 4.1 Introduction to Object Oriented Programming (OOP)

PyGame - Unit 4 Objectives By the end of this unit you will be able to: –Define an object and how it is useful to programmers. –Describe a class and how it relates to programming objects –Describe methods and how they relate to classes and functions –Create and use Classes, Methods and Objects.

PyGame - Unit 4 What is an Object A software construct that allows data to be merged with its related programming logic. A thing that can perform a set of related activities. Example object: Zombie: –Data/Properties: health; attackPower; etc. –Activities: walk; attack; climb; etc.

Properties and Methods PyGame - Unit 4 Why can’t they make up their minds? Properties = variables or attributes Methods = functions

PyGame - Unit 4 Object Example Shooter “1943” Airplane Object:

PyGame - Unit 4 Airplane Object in “1943” Example: “1943” (A classic top-down shooter game) –Object: airplane Properties (Data) - speed; health; shields; image Methods (functions) – move; fire; shield

PyGame - Unit 4 Class Blueprint for constructing objects Programming code and data used to create one or more objects. The code is broken into functions called Methods. The official term for the data is Properties.

PyGame - Unit 4 Classes are like Blueprints Blueprint = design for one or more homes: Class = design for one or more objects: Class EnemyPlane: …

PyGame - Unit 4 Class Diagrams Class Name: Data: Methods: (functions)

PyGame - Unit 4 Creating Objects Instance – The name of an object in memory. Format: objectVariableName = ClassName() Example: enemyObj = EnemyPlane() –Note: the suffix Obj is not necessary, it helps us remember that it is an object instance.

PyGame - Unit 4 Object Instances enemyObj = EnemyPlane() enemyObj –can be any name you like –Points to the place in memory where the object instance exists.

Instance Example (Dog Class) Dog is the class: Rayne is the object instance: After the Rayne object instance is created, it has the same properties and access to the methods defined in the class. PyGame - Unit 4

Defining our Ship Class (data) Class Ship: speed = 5 health = 20

PyGame - Unit 4 The getSpeed() Method (function) class Ship: speed = 5 health = 20 getSpeed() return self.speed Why self.speed ???

PyGame - Unit 4 Creating an Instance of “Ship” Object Creating the shipObj instance. shipObj = Ship() Printing the health for the shipObj print(shipObj.health) Returns: 20 (the default value set within the class)

PyGame - Unit 4 Modifying a Object’s Parameter shipObj = Ship() Making shipObj very healthy shipObj.health = 500

PyGame - Unit 4 Multiple Object Instances class EnemyShip: speed = 4 health = 15 enemyObj1 = EnemyShip() enemyObj2 = EnemyShip() enemyObj3 = EnemyShip() enemyObj1.speed = 5 enemyObj2.speed = 6 enemyObj3.speed = 7 print(enemyObj1.speed, enemyObj2.speed, enemyObj3.speed) Returns: 5 6 7

PyGame - Unit 4 The Power of OOP Instantiation (ie. multiple enemies) Objects can be passed into functions –Printing the data of shipObj: printShipData(shipObj) Sprites –Displaying and moving images on screen –Collision detection –Sprite Groups: Putting sprites in a list (Supports displaying, updating and collision detection)

PyGame - Unit 4 Read the textbook entitled “Introduction to Computer Science Using Python and PyGame” –Read CH 13 PP. 105 – 112 –4-1 Exercises See the Intranet for exercise details:Intranet Reading / Exercises

PyGame - Unit 4 PyGame – 4.2 Object Oriented Programming (OOP) Inheritance and Constructors

PyGame - Unit 4 Objectives By the end of this unit you will be able to: –Define inheritance and constructors as they apply to object oriented programming. –Utilize constructor methods to execute programming logic when an object is instantiated. –Create a class that inherits the methods and properties of another class.

Constructor Constructor – A special function that is called any time an instance of that class is created. » Courtsey of Borderlands 2 PyGame - Unit 4

Constructor Runs only once; only when the object is first created (instantiated) May be used to: –Get information from data source –Create variables –Etc. PyGame - Unit 4

Sample Constructor “A new dog is born!” is printed when an instance of Dog() is created. class Dog(): # Constructor # Called when creating an object of this type def __init__ (self): print ("A new dog is born !") # Create the myDog object from the Dog()class. myDog = Dog() PyGame - Unit 4

Constructor Input Parameter class Dog(): name = '' def __init__ (self, newName): self.name = newName # Create the myDog object from the # Dog()class. myDog = Dog('Spot') print (myDog.name) # Prints “Spot” PyGame - Unit 4

Constructors and self class Dog (): name = 'Rover' # Only useful the first time def __init__ (self, name): # This will print "Rover" print (self.name) # Stays in memory until object is deleted. # This will print "Spot" print(name) # Create the myDog object myDog = Dog('Spot') PyGame - Unit 4

Self class Dog (): self.breed = 'Mutt' # Stays in memory until object is deleted. def __init__ (self ): # This will print "Rover" print (self.breed) # Create the myDog object myDog = Dog() PyGame - Unit 4

Inheritance Inheritance – When a class copies all methods and properties from another class. Sprite class –Our custom classes will inherit the methods and properties of the Sprite class. PyGame - Unit 4

Inheriting From the Person Class Customer and Employee inherit the methods and parameters of the Person class. Parent Class – Person Child Classes – Employee; Customer PyGame - Unit 4

Inheritance Example PyGame - Unit 4 class Person (): self.name = '' class Employee (Person): self.job_title = '' class Customer (Person): self. ='' johnSmith = Person () johnSmith.name = 'John Smith' janeEmployee = Employee () janeEmployee.name = 'Jane Employee' janeEmployee.jobTitle = 'Web Developer' bobCustomer = Customer () bobCustomer.name = 'Bob Customer' bobCustomer. = '

PyGame - Unit 4 Pg4-2-0: Read PP from the "Introduction to Computer Science Using Python and PyGame" text (Class constructors) (Inheritance) See the Intranet for exercise details:Intranet Reading / Exercises

PyGame - Unit 4 PyGame – 4.3 PyGame Sprites An Introduction

PyGame - Unit 4 Objectives By the end of this unit you will be able to: –Define a Sprite and describe how it is used in 2d games. –Create a class that inherits the Sprite class. –Create an instance of the class that inherits from Sprite.

Sprite Sprite – 2 dimensional image that is part of a larger graphical scene. Originally supported by hardware Used for: –Animation –Collision detection –Managing groups of sprites –Much Much more… PyGame - Unit 4

Inheriting from a Sprite The Player class inherits all methods and properties of the Sprite class. The Sprite class is in the pygame.sprite module. # *** Player Class *** class Player(pygame.sprite.Sprite): PyGame - Unit 4

Call Sprite constructor Call the constructor for the Sprite from within the class that is based upon Sprite. –Allows all sprites to initialize # *** Player Class *** class Player(pygame.sprite.Sprite): def __init__(self): # Call the parent class (Sprite) constructor pygame.sprite.Sprite.__init__(self) … PyGame - Unit 4

Example (Player Class) # *** Player Class *** class Player(pygame.sprite.Sprite): def __init__(self): # Call the parent class (Sprite) constructor pygame.sprite.Sprite.__init__(self) # Set the image and rect variables self.image = pygame.image.load(PLYR_SHP).convert() self.rect = self.image.get_rect() playerObj = Player()# Create an instance of “Player” playerObj.rect.x = 10# Set the x coordinate playerObj.rect.y = 400 # Set the y coordinate PyGame - Unit 4

Pg4-3-0: Read PP from the "Introduction to Computer Science Using Python and PyGame" text (Create the Triangle class) –See the Intranet for exercise details:Intranet Reading / Exercises

PyGame - Unit 4 PyGame – 4.4 PyGame Sprites Sprite Groups; Moving Groups of Sprites; Collision Detection

PyGame - Unit 4 Objectives By the end of this unit you will be able to: –Create Sprite Groups –Use Sprite Groups to move sprites on the screen. –Define collision detection –Use Sprite Groups to implement collision detection

Sprite Groups Sprite Group – A PyGame feature that assists us with working with more than one sprite. Why Sprite Groups: –Collision Detection: Determining if a sprite in one group collides with a sprite in another group. Or if a non-grouped Sprite collides with a sprite in a group. –Group Updates: Calling update() method for all sprites in the group with one command. PyGame - Unit 4

Adding a Sprite to a Group allSpritesGroup = pygame.sprite.Group() # *** Enemy Class *** class Enemy(pygame.sprite.Sprite): def __init__(self): # Call the parent class (Sprite) constructor pygame.sprite.Sprite.__init__(self) # Set the image and rect variables self.image = pygame.image.load(ENEMY_SHIP).convert() self.rect = self.image.get_rect() enemyObj = Enemy()# Create an instance of “Enemy” enemyObj.rect.x = 10# Set the x coordinate enemyObj.rect.y = 400 # Set the y coordinate allSpritesGroup.add(enemyObj) PyGame - Unit 4

Sprite Groups (Enemy Class) allSpritesGroup = pygame.sprite.Group() # *** Enemy Class *** class Enemy(pygame.sprite.Sprite): def __init__(self, color): # Call the parent class (Sprite) constructor pygame.sprite.Sprite.__init__(self) self.image = pygame.image.load(ENEMY_SHIP_1).convert() self.rect = self.image.get_rect() enemyObj = Enemy() # Create an instance of “Enemy” enemyObj.rect.x = 10 # Set the x coordinate enemyObj.rect.y = 400 # Set the y coordinate allSpritesGroup.add(enemyObj) Several instances of the Enemy class are placed in the allSpritesGroup. –allSpritesGroup is used for collision detection and moving sprites on the screen. PyGame - Unit 4

Updating using Sprite Groups class Enemy(pygame.sprite.Sprite): def __init__(self, color): # Call the parent class (Sprite) constructor pygame.sprite.Sprite.__init__(self) self.image = pygame.image.load(ENEMY_SHIP_1).convert() self.rect = self.image.get_rect() def update(self): self.rect.y += 5 PyGame - Unit 4

Updating and Drawing Sprite Groups # Update enemyGroup to move enemy ships. enemyGroup.update() # Clear the screen DISPLAYSURF.fill(WHITE) # Draw all enemy sprites in enemyGroup enemyGroup.draw(DISPLAYSURF) fpsClock.tick(FPS) pygame.display.flip() PyGame - Unit 4

Exercise Do PyGame exercise You can find the details on the Intranet. PyGame - Unit 4

Collision Detection pygame.sprite.groupcollide(group1, group2, True, True) Group1 = The first sprite group to compare Group2 = The second sprite group to compare True (the first one) = Delete objects in group 1 that have collided with objects in group 2. True (the second one) = Delete objects in group 2 that have collided with objects in group 1. PyGame - Unit 4

Exercise Do PyGame exercise You can find the details on the Intranet. PyGame - Unit 4