在 pygame 中繪制線條粗細有問題

Question

這是我使用 pygame 繪制的板： https://i.stack.imgur.com/Hne6A.png

當我在圖像上標記它們時，我遇到了最后兩行粗細的錯誤。 我相信我的代碼中的 if 語句有問題，但我不太明白，它不會生效。

這是上面繪制板的代碼：

import pygame, sys


pygame.init()

width, height = 750, 750
rows, cols = 9, 9
BLACK = (0,0,0)

screen = pygame.display.set_mode((width, height))
screen.fill((255, 255, 255, 255))

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

    surf = pygame.Surface((600, 600))
    surf.fill((255,255,255))

    padding = surf.get_width()/9
    for i in range(rows+1):
        if i % 3 == 0:
            thick = 4
        else:
            thick = 1

        pygame.draw.line(surf, BLACK, (0, i*padding), (width, i*padding), width=thick)
        pygame.draw.line(surf, BLACK, (i*padding, 0), (i*padding, height), width=thick)

    

    surf_center = (
        (width-surf.get_width())/2,
        (height-surf.get_height())/2
    )
    screen.blit(surf, surf_center)
    pygame.display.update()
    pygame.display.flip()

Answer 1

要繪制粗線，將一半的粗細應用到線的兩側。 最簡單的解決方案是使目標表面稍微大一點，並向線條的坐標添加一個小的偏移量。
出於性能原因，我還建議在應用程序循環之前創建表面並在應用程序循環中連續blit它：

import pygame, sys

pygame.init()

width, height = 750, 750
rows, cols = 9, 9
BLACK = (0,0,0)

screen = pygame.display.set_mode((width, height))

surf_size = 600
surf = pygame.Surface((surf_size+4, surf_size+4))
surf.fill((255,255,255))
padding = surf_size/9
for i in range(rows+1):
    thick = 4 if i % 3 == 0 else 1
    offset = i * padding + 1
    pygame.draw.line(surf, BLACK, (0, offset), (width, offset), width=thick)
    pygame.draw.line(surf, BLACK, (offset, 0), (offset, height), width=thick)

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
            
    screen.fill((255, 255, 255, 255))
    screen.blit(surf, surf.get_rect(center = screen.get_rect().center))
    pygame.display.update()
    pygame.display.flip()

pygame.quit()
sys.exit()

Answer 2

下面的代碼應該可以解決問題。 問題是pygame.draw.line中的width繪制在線的中間。 因此，邊界線實際上被剪成兩半，因為沒有考慮一側的一半和另一側的另一半。 但要注意的是，如果厚度均勻，則邊界上的偏移量為 1，因為其中一側的寬度較大。

即使厚度 ( bold_think ) 升高或降低，下面的算法也能完美運行，網格外沒有任何間隙。

厚度4	厚度8	15的思考

import pygame
import sys

pygame.init()

width, height = 750, 750
rows, cols = 9, 9
BLACK = (0, 0, 0)

screen = pygame.display.set_mode((width, height))
screen.fill((255, 255, 255, 255))

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

    surf = pygame.Surface((600, 600))
    surf.fill((255, 255, 255))

    bold_thick = 4
    # Calculates the offset of 1 for the even widths
    thick_offset = (bold_thick - 1) % 2
    offset = (bold_thick / 2) - thick_offset

    # The padding should take into account the borders
    padding = (surf.get_width() - bold_thick) / 9
    for i in range(rows+1):
        if i % 3 == 0:
            thick = bold_thick
        else:
            thick = 1

        pygame.draw.line(surf, BLACK, (0, i*padding + offset),
                         (width, i*padding + offset), width=thick)
        pygame.draw.line(surf, BLACK, (i*padding + offset, 0),
                         (i*padding + offset, height), width=thick)

    surf_center = (
        (width-surf.get_width())/2,
        (height-surf.get_height())/2
    )
    screen.blit(surf, surf_center)
    pygame.display.update()
    pygame.display.flip()