Get started with pyGame

Recent learning pygame I've got the module , Because the official documents are in English , Translation reading is not very friendly , So I found a lot of them on the Internet pygame Knowledge sharing of modules , A brief summary is here , I hope it will be helpful to the little partners who study together .
（1） WeChat official account ： Na translation station （ There are more detailed pygame The tutorial is accompanied by relevant practical exercises ）
（2） WeChat official account ： Data help Club( Brief content )
（3） Personal blog site ：https://www.xin3721.com/python3/（ This article is from this author , It is also the best one for me to understand briefly , As sharing ）
（4） Official documents ：https://www.pygame.org/docs/

The goal is

1. Project preparation
2. Use pygame Create a graphics window
3. understand Images And realize image rendering
4. understand Game cycle and Game clock
5. understand spirit and Spirit group

Project preparation

1. newly build Aircraft battle project
2. Create a new one hm_01_pygame introduction .py
3. Import Game material pictures

The first impression of the game

• Some of the A still image Drawn to the Game window in
• according to User interaction Or other circumstances , Move These images , Produce animation
• according to Between images Whether there is overlap , Judge Whether the enemy plane has been destroyed Other information

01. Use pygame Create a graphics window

Subsection objectives

1. Game initialization and exit
2. Understand the coordinate system in the game
3. Create the main game window
4. Simple game loop

The picture material can be draw To The window of the game On , Before developing a game, you need to know How to create a game window ！

1.1 Game initialization and exit

• To use pygame Before all the functions provided , Need to call init Method
• Before the end of the game, you need to call quit Method

import pygame

pygame.init()

#  Game code ...

pygame.quit()

1.2 Understand the coordinate system in the game

• Coordinate system
  • origin stay top left corner (0, 0)
  • x Axis Horizontally to Right , Gradually increase
  • y Axis In a vertical direction Next , Gradually increase

• In the game , All visible elements are represented by Rectangular area to describe the location

  • To describe a rectangular area, there are four elements ：(x, y) (width, height)

• pygame A special class is provided pygame.Rect Used to describe Rectangular area

Rect(x, y, width, height) -> Rect

Tips

• pygame.Rect It's a special class , It just encapsulates some digital calculations
• Don't execute pygame.init() Methods can also be used directly

Case drills

demand

1. Definition hero_rect Rectangular description The position and size of the hero
2. Output heroic Coordinate origin （x and y）
3. Output heroic Size （ Width and Height ）

hero_rect = pygame.Rect(100, 500, 120, 126)

print(" Coordinate origin  %d %d" % (hero_rect.x, hero_rect.y))
print(" Hero size  %d %d" % (hero_rect.width, hero_rect.height))
# size  Property will return the rectangle  ( wide ,  high )  Tuples 
print(" Hero size  %d %d" % hero_rect.size)

1.3 Create the main game window

• pygame There is a special modular pygame.display Used to create 、 management Game window

set_mode Method

set_mode(resolution=(0,0), flags=0, depth=0) -> Surface

• effect —— Create a game display window
• Parameters
  • resolution Specifies the of the screen wide and high , The window size created by default is consistent with the screen size
  • flags Parameter specifies additional options for the screen , For example, whether the screen is full or not , By default, there is no need to pass
  • depth The parameter represents the number of bits of the color , Default auto match
• Return value
  • temporary It can be understood as The screen of the game , Elements of the game All need to be drawn to The screen of the game On
• Be careful ： Variable records must be used set_mode method ！ because ： All subsequent image rendering is based on this return result

#  Create the main game window 
screen = pygame.display.set_mode((480, 700))

1.4 Simple game loop

• In order to make the game program start , No immediate exit , Usually add a... In the game program Game cycle

• So-called Game cycle It's just one. Infinite loop

• stay Create game window code below , Add an infinite loop

  • Be careful ： The game window does not need to be created repeatedly

#  Create the main game window 
screen = pygame.display.set_mode((480, 700))

#  Game cycle 
while True:
    pass

02. understand Images And realize image rendering

• In the game , Can see Game elements Most of them are Images

  • image file Initially saved on disk , If needed , First step Need Is loaded into memory

• On the screen See the content of an image , There are three steps to follow ：

  1. Use pygame.image.load() Load image data
  2. Use Game screen object , call blit Method Draw the image to the specified position
  3. call pygame.display.update() Method to update the display of the entire screen

Tips ： To see the results drawn on the screen , You have to call pygame.display.update() Method

Code walkthrough I —— Draw the background image

demand

1. load background.png Create a background
2. take background Drawn on the screen (0, 0) Location
3. Call the screen update to display the background image

#  Draw the background image 
# 1>  Load image 
bg = pygame.image.load("./images/background.png")

# 2>  Draw on the screen 
screen.blit(bg, (0, 0))

# 3>  Update display 
pygame.display.update()

Code walkthrough II —— Draw a hero image

demand

1. load me1.png Create a hero plane
2. take Hero plane Drawn on the screen (200, 500) Location
3. Call the screen update to display the aircraft image

# 1>  Load image 
hero = pygame.image.load("./images/me1.png")

# 2>  Draw on the screen 
screen.blit(hero, (200, 500))

# 3>  Update display 
pygame.display.update()

Transparent image

• png The format of the image is supported transparent Of
• When drawing an image , Transparent areas Nothing will be shown
• But if There is already content below , Meeting through Transparent areas Show it

understand update() The role of methods

Can be in screen Object complete all blit After method , Unified call once display.update Method , It can also be on the screen See the final drawing result

• Use display.set_mode() Created screen Object is a Screen data object in memory

  • It can be understood as Oil Painting Of canvas

• screen.blit Method can draw a lot on the canvas Images

  • for example ： hero 、 Enemy planes flying in and out 、 The bullet …
  • These images There may be Will each other Overlap or overlay

• display.update() Will canvas Of final result Draw on the screen , This can Improve screen rendering efficiency , Increase the fluency of the game

Case adjustment

#  Draw the background image 
# 1>  Load image 
bg = pygame.image.load("./images/background.png")

# 2>  Draw on the screen 
screen.blit(bg, (0, 0))

#  Draw a hero image 
# 1>  Load image 
hero = pygame.image.load("./images/me1.png")

# 2>  Draw on the screen 
screen.blit(hero, (200, 500))

# 3>  Update display  - update  Method will put all the results drawn before , Update to the screen window at one time 
pygame.display.update()

03. understand Game cycle and Game clock

Now? Hero plane It has been drawn on the screen , How can we make the plane move ？

3.1 The principle of animation in the game

• Follow The movie The principle is similar , Animation effects in the game , Essentially, Fast Draw on the screen Images

  • The movie will be multiple Still film continuity 、 Fast Playback of , Produce a coherent visual effect ！

• Usually on the computer Draw per second 60 Time , Can achieve very continuity The high quality Animation effect of

  • The result of each plot is called frame Frame

3.2 Game cycle

The two components of the game

The beginning of the game cycle Means The official start of the game

Role of game cycle

1. Make sure the game Will not exit directly

2. Change image position —— Animation effect

   • every other 1 / 60 second Move the position of all the images
   • call pygame.display.update() Update screen display

3. Detect user interaction —— Key 、 Mouse, etc. …

3.3 Game clock

• pygame A special class is provided pygame.time.Clock It is very convenient to set the screen drawing speed —— Refresh frame rate

• To use Clock object Two steps are needed. ：

  • 1） stay Game initialization Create a Clock object
  • 2） stay Game cycle Let the clock object call tick( Frame rate ) Method

• tick The method will be based on Last called time , Automatic setting Game cycle Delay in

# 3.  Create a game clock object 
clock = pygame.time.Clock()
i = 0

#  Game cycle 
while True:

    #  Set the screen refresh frame rate 
    clock.tick(60)

    print(i)
    i += 1

3.4 Simple animation of Heroes

demand

1. stay Game initialization Define a pygame.Rect The variable records the hero's initial position
2. stay Game cycle Every time hero Of y - 1 —— Move up
3. y <= 0 Move the hero to the bottom of the screen

Tips ：

• Every time you call update() Before method , Need to put All the game images are redrawn
• And it should The first Redraw background image

# 4.  Define the hero's initial position 
hero_rect = pygame.Rect(150, 500, 102, 126)

while True:

    #  You can specify the frequency of code execution inside the loop body 
    clock.tick(60)

    #  Update hero location 
    hero_rect.y -= 1

    #  If you move out of the screen , Move the top of the hero to the bottom of the screen 
    if hero_rect.y <= 0:
        hero_rect.y = 700

    #  Draw a background picture 
    screen.blit(bg, (0, 0))
    #  Draw a hero image 
    screen.blit(hero, hero_rect)

    #  Update display 
    pygame.display.update()

Homework

1. Heroes fly up , When After the hero completely flies out of the screen from above
2. Move the plane to the bottom of the screen

if hero_rect.y + hero_rect.height <= 0:
    hero_rect.y = 700

Tips

• Rect Properties of bottom = y + height

if hero_rect.bottom <= 0:
    hero_rect.y = 700

3.5 In the game cycle monitor event

event event

• After the game starts , What the user does for the game
• for example ： Click the close button , The click of a mouse , Press the keyboard …

monitor

• stay Game cycle in , Judge users Specific operation

Only Capture To the user's specific operation , In order to make a targeted response

Code implementation

• pygame Pass through pygame.event.get() You can get What the user is currently doing Of List of events

  • Users can do many things at the same time

• Tips ： This code is very fixed , Almost all pygame Game capital Be the same in essentials while differing in minor points ！

#  Game cycle 
while True:

    #  Set the screen refresh frame rate 
    clock.tick(60)

    #  Event monitoring 
    for event in pygame.event.get():

        #  Judge whether the user has clicked the close button 
        if event.type == pygame.QUIT:
            print(" Quit the game ...")

            pygame.quit()

            #  Just exit the system 
            exit()

04. understand spirit and Spirit group

4.1 spirit and Spirit group

• In the case just completed , Image loading 、 Position change 、 The plot Programmers need to write code to deal with

• To simplify development steps ,

pygame Two classes are provided :

• pygame.sprite.Sprite —— Storage Image data image and Location rect Of object
• pygame.sprite.Group

spirit

• In game development , Usually put The object that displays the image It's called spirit Sprite

• spirit There are two important attributes

  • image The image to display
  • rect The image should be displayed on the screen

• default update() Method did nothing

  • Subclasses can override this method , Every time the screen is refreshed , Update wizard location

• Be careful ：

  pygame.sprite.Sprite It didn't provide image and rect Two attributes

  • Need programmers from pygame.sprite.Sprite Parturient
  • And in Subclass Of Initialization method in , Set up image and rect attribute

Spirit group

• One Spirit group It can contain more than one spirit object

• Call the update() Method

  • Sure Automatically call Every elf in the Group Of update() Method

• Call the draw( Screen objects ) Method

  • Can be Every elf in the Group Of image Draw on rect Location

Group(*sprites) -> Group

Be careful ： You still need to call pygame.display.update() To see the final result on the screen

4.2 Derived sprite subclass

1. newly build plane_sprites.py file
2. Definition GameSprite Inherited from pygame.sprite.Sprite

Be careful

• If the Parent class No object
• In rewriting Initialization method when , must do First super() Click the parent class __init__ Method
• Ensure the implementation of... In the parent class __init__ The code can be executed normally

attribute

• image Sprite image , Use image_name load
• rect Sprite size , The default image size is
• speed Spirit movement speed , The default is 1

Method

• update Call... Within the game loop each time the screen is updated

  • Let the elves self.rect.y += self.speed

Tips

• image Of get_rect() Method , Can return pygame.Rect(0, 0, Image width , High image ) The object of

import pygame


class GameSprite(pygame.sprite.Sprite):
    """ Game wizard base class """
    
    def __init__(self, image_name, speed=1):
        
        #  Call the initialization method of the parent class 
        super().__init__()
        
        #  Load image 
        self.image = pygame.image.load(image_name)
        #  Set dimensions 
        self.rect = self.image.get_rect()
        #  Record speed 
        self.speed = speed

    def update(self, *args):
        
        #  Move vertically by default 
        self.rect.y += self.speed
        

4.3 Use Game Genie and Spirit group Create enemy aircraft

demand

• Use the just derived Game Genie and Spirit group establish Enemy planes flying in and out And realize enemy aircraft animation

step

1. Use from Import plane_sprites modular

   • from The imported module can Use it directly
   • import The imported module needs to pass Module name . To use

2. stay Game initialization establish Sprite objects and Sprite group objects

3. stay In the game cycle Give Way Spirit group Respectively called update() and draw(screen) Method

duty

• spirit
  • encapsulation Images image、 Location rect and Speed speed
  • Provide update() Method , According to the needs of the game , Update location rect
• Spirit group
  • contain Multiple Sprite objects
  • update Method , Let all sprites in the sprite group call update Method to update the location
  • draw(screen) Method , stay screen Draw all the sprites in the sprite group on

Implementation steps

1. Import plane_sprites modular

from plane_sprites import *

2. Modify the initialization code

#  Create enemy spirit and spirit group 
enemy1 = GameSprite("./images/enemy1.png")
enemy2 = GameSprite("./images/enemy1.png", 2)
enemy2.rect.x = 200
enemy_group = pygame.sprite.Group(enemy1, enemy2)

3. Modify the code of the game cycle

#  Let the enemy crew call  update  and  draw  Method 
enemy_group.update()
enemy_group.draw(screen)

#  Update screen display 
pygame.display.update()