我的班级在这个简单的角色移动脚本中无法正常工作

Question

import pygame, sys
from pygame.locals import *

bifl = 'screeing.jpg'
milf = 'char_fowed_walk1.png'

pygame.init()

screen = pygame.display.set_mode((640, 360),0, 32)
background = pygame.image.load(bifl).convert()
mouse_c = pygame.image.load(milf).convert_alpha()

x, y = 0, 0
movex, movey = 0, 0


class move:
    def moveUp():
        movey =- 0.3
    def moveDown():
        movey =+ 0.3
    def moveLeft():
        movex =- 0.3
    def moveRight():
        movex =+ 0.3

    def stopUp():
        movey = 0
    def stopDown():
        movey = 0
    def stopLeft():
        movex = 0
    def stopRight():
        movex = 0




while True:
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()
        if event.type == KEYDOWN:
            if event.key == K_LEFT:
                move.moveLeft()
            elif event.key == K_RIGHT:
                move.moveRight()
            elif event.key == K_UP:
                move.moveUp()
            elif event.key == K_DOWN:
                move.moveDown()

        if event.type == KEYUP:
             if event.key == K_LEFT:
                 move.stopLeft()
             elif event.key == K_RIGHT:
                 move.stopRight()
             elif event.key == K_UP:
                 move.stopUp()
             elif event.key == K_DOWN:
                 move.stopDown()

    x += movex
    y += movey

    screen.blit(background, (0, 0))
    screen.blit(mouse_c, (x, y))

    pygame.display.update()

when i run this everything works only that the player doesn't move, i testes this without classes and functions and it work so it's definitely something to do with the classes i added. pygame is installed correctly i am using python 2.7 and i have used pygame in other scripts and it works fine.

Answer 1

Since movex and movey are inside a function, they are locals, their values will never change outside the function (it will always be 0 from the movex, movey = 0, 0 line). Read about variable scopes in Python.

You have to either put a global movex and global movey inside the move class or return the value of movex and movey on the functions, and use that returned value on the event capturing loop, like:

if event.key == K_LEFT:
    y += move.stopLeft()

I'd reorganize the entire thing and have a separate file for the move functions instead of a class, though.

Answer 2

I'd take a totally different approach and store your x/y coordinations in a object that knows how to alter them:

import pygame, sys
from pygame.locals import *

class Position(object):
    def __init__(self):
        self.x = 0
        self.y = 0

    def moveUp(self):
        self.y =- 0.3

    def moveDown(self):
        self.y =+ 0.3

    def moveLeft(self):
        self.x =- 0.3

    def moveRight(self):
        self.x =+ 0.3

pos = Position()

movemap = {
    (KEYDOWN, K_LEFT): pos.moveLeft,
    (KEYDOWN, K_RIGHT): pos.moveRight,
    (KEYDOWN, K_UP): pos.moveUp,
    (KEYDOWN, K_DOWN): pos.moveDown,
}

bifl = 'screeing.jpg'
milf = 'char_fowed_walk1.png'

pygame.init()

screen = pygame.display.set_mode((640, 360),0, 32)
background = pygame.image.load(bifl).convert()
mouse_c = pygame.image.load(milf).convert_alpha()

while True:
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()

        try:
            action = movemap[(event.type, event.key)]
        except KeyError:
            continue

        action()

    screen.blit(background, (0, 0))
    screen.blit(mouse_c, (pos.x, pos.y))

    pygame.display.update()

First, the Pythony stuff: in Python 2.7, classes should explicit inherit from object . That's the class Position(object) part. Also, the first argument to an instance method is an instance object. That's all the self stuff. Finally, you don't have to put regular functions in classes. It's perfectly OK to have a dosomething(): return 5 function at the top level of a module.

Now, on to the rest:

A Position object knows how to mutate its own state. By making a dict that maps combinations of key events to methods, you don't have to have those long if/elif/elif blocks. You can also ignore every keyup event; just don't do anything unless the user is pressing a key.

Answer 3

Zooming in a bit:

movex =- 0.3

You want

movex -= 0.3

your version is actually understood by python to be:

movex = (- 0.3)

Which is to say, negate 0.3 and assign the result to a local variable named movex , Likewise: movex =+ 0.3 is "make sure 0.3 is a number and assign it to movex".

In place operators put the operator before the equal sign. Just fixing that will give you a somewhat helpful traceback, telling you that you can't assign a variable that hasn't been declared yet, since it still looks to the python interpreter like you want movex and movey to be locals. Fixing that would be:

def moveLeft(self):
    global movex
    movex -= 0.3