Core principles of video games

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Have you ever played with such a toy when you were a child ： A piece of hard paper , One side is painted with a bird , A cage is painted on one side . Stick a thin stick under the hard paper . Use your hand to rotate the thin rod , Let the two sides of the hard paper alternate quickly , You will see the bird being caged .

This phenomenon is called Visual persistence , also called afterglow effect . The nature of the human eye makes the light signal after entering , It will last for a short time , This period of time is about 0.1~0.4 second . The movie 、 Animation is achieved by using this phenomenon , Play static pictures quickly and continuously , Form a moving picture that looks continuous . Games are no exception .

Take a look at a passage Python Famous game library in  pygame（ To be installed ） Write a “ Empty game ” Code ：

Although this code only shows a background image , There is no game function at all , But this is already a basic game code framework .

Notice one in the code while True The cycle of , The note is “ The main cycle of the game ”. This is the main part of the game . Each cycle is equivalent to a static picture , The program is running , Just modify this picture , There is a dynamic effect .

Different from animation , In the game, you should not only play pictures , It also needs to deal with the interaction between the player's operation and the content in the game . So here while In circulation , I have to receive the input of players , And deal with various logical judgments in the game 、 motion 、 Collision and so on .

In the main loop of the above code , Made a response to the exit event ：

for event in pygame.event.get():
    if event.type == pygame.QUIT:
        # Exit the program after receiving the exit event 
        pygame.quit()
        exit()

Then draw the image into the window ：

screen.blit(background, (0,0))

Last , Update the whole window ：

pygame.display.update()

If you've seen it “ Clay animation ”, Then you can imagine the whole game process as the process of shooting clay animation ：

• every time ,screen.blit() It's equivalent to putting a doll 、 The set moves a little bit

• pygame.display.update() Press the shutter to take a new picture

• and if event.type == pygame.QUIT: Is judging , Did the director call it quits

All this is handled by the computer in a very short time , So that players feel coherent .

Although this is a very simple game logic , But in terms of core principles , Most games are interlinked . Even cool 3D Games or large-scale online games , They also pass through a main game loop , Update various game logic and display effects in the cycle to operate .

Some large 3D The game needs to do many things in one cycle , Complex physical operations are required 、 Calculate the illumination effect of light 、 Intelligence to handle a large number of computer characters 、 Network information communication, etc . On computers with low configuration , These calculations take more time , The game refreshes the screen more slowly . This is what we often hear “ The frame rate of a game is low ” Why , At this time, you will feel that the game is not smooth .

The above is a brief introduction to the core principles of video games . If you are a novice interested in game development , You can see what I wrote before pygame Series of tutorials ：

Pygame introduction - Imitate wechat to play airplane Games

Although not as popular as the game engine now “ Foolishness ” operation , But implementing the game through code can make you have a deeper understanding of the underlying logic of the game .

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