python - 如何在font.render行中包含此变量？

我正在尝试将骰子掷骰的结果包含在屏幕上的文本blit字符串中，"You rolled a" + roll

我相信问题与while循环“运行时：”或我编写代码的顺序有关，但是我不知道如何解决它。任何帮助，将不胜感激。我是StackOverflow的新手，所以如果标题/解释不够清楚，请您提前道歉。

from random import *
import pygame
import sys

from pygame import rect

"""SETTINGS"""
global roll
clock = pygame.time.Clock()
fps = 60

WHITE = (255, 255, 255)
GREY = (200, 200, 200)
BLACK = (0, 0, 0)
RED = (255, 0, 0)
BLUE = (0, 0, 255)

WIDTH = 520
HEIGHT = 500

bg = (255, 255, 255)

"""functions"""


def dice():
    roll = randint(1, 6)
    print("You rolled a ", roll)


"""init"""

pygame.init()
pygame.font.init()
screen = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("Dice")

"""dice image"""

image = pygame.image.load("diceImage.gif").convert()
image2 = image.get_rect()
imageUsed = pygame.transform.scale(image, (WIDTH, HEIGHT))

"""text object"""
surf = pygame.Surface((WIDTH, 60))
font = pygame.font.SysFont("comicsansms", 37)
text = font.render("Click the dice to roll a number", True, (30, 128, 190))

surf2 = pygame.Surface((400, 60))
text2 = font.render(("You rolled a", roll), True, (30, 128, 190))

running = True

while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            quit()
        if event.type == pygame.MOUSEBUTTONDOWN:
            dice()
            mouse_pos = event.pos
            if image2.collidepoint(mouse_pos):
                print('button was pressed at {0}'.format(mouse_pos))

    screen.fill(bg)
    screen.blit(imageUsed, (0, 0))
    screen.blit(surf, (0, 0))
    screen.blit(surf2, (50, 450))
    screen.blit(text, (0, 0))
    screen.blit(text2, (50, 450))
    pygame.display.update()
    clock.tick(fps)

错误信息：

Traceback (most recent call last):
  File "C:/Users/lee/Documents/PYTHON/Dice/Dice.py", line 50, in <module>
    text2 = font.render(("You rolled a", roll), True, (30, 128, 190))
NameError: name 'roll' is not defined

最佳答案

您将global statement放在错误的位置。 global语句意味着列出的标识符将被解释为当前范围内的全局变量。
在全局名称空间中声明并初始化roll，但在函数global中使用dice语句在全局名称空间中设置variabel roll：

roll = 1

def dice():
    global roll
    roll = randint(1, 6)
    print("You rolled a ", roll)

您必须先通过roll将数值str()转换为字符串，然后才能在render()中使用它并呈现文本Surface：

text2 = font.render(("You rolled a " + str(roll)), True, (30, 128, 190))

关于python - 如何在font.render行中包含此变量？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/60140839/