Pygame collidepoint（）工作不正常

Question

我正在做一个游戏，你砍树，并希望它，使你只能砍树半径为50像素（约1树在每个方向上）的位置在游戏中（由一个正方形表示）。问题是，当我测试它时，我发现它只工作了一次，我的意思是你只需要移动来阻止半径屏障工作，你就可以摧毁任何一棵树。有人能告诉我为什么会发生这种情况以及如何解决它吗？代码如下：

# I'll only put in the bit that makes the bug
# Tree objects are sorted in a Tree class with a method destroy() to destroy the tree
for tree in trees:
    if pygame.mouse.get_pressed()[0] and tree.trunk.collidepoint(pygame.mouse.get_pos()):
        mouse_x, mouse_y = pygame.mouse.get_pos()
        print('clicked tree') # For testing purposes
        if mouse_x < x + 51 and mouse_y < y + 51:
            countdown = 3
            destroy_tree = tree
        elif mouse_x < x + 51 and mouse_y < y - 51:
            countdown = 3
            destroy_tree = tree
        elif mouse_x < x - 51 and mouse_y < y - 51:
            countdown = 3
            destroy_tree = tree
        elif mouse_x < x - 51 and mouse_y < y + 51:
            countdown = 3
            destroy_tree = tree

Answer 1

您必须评估坐标是否在一个范围内，在一个相同的条件下。你实际做的是：

if x < value + 50:
   countdown = 3
elif x > value - 50:
   countdown = 3

始终满足其中一个条件，并在任何情况下设置countdown

条件必须是：

if x - 51 < mouse_x < x + 51:
    if y - 51 < mouse_y < y + 51:
        countdown = 3
        destroy_tree = tree

此外，通过使用^{}可以简化算法。例如：

mouse_x, mouse_y = pygame.mouse.get_pos()
for tree in trees:
    if pygame.mouse.get_pressed()[0] and tree.trunk.collidepoint((mouse_x, mouse_y)):
        print('clicked tree') # For testing purposes

        dx = mouse_x - x
        dy = mouse_y - y
        if abs(dx) <= 50 and abs(dy) <= 50:
            countdown = 3
            destroy_tree = tree

或者，您可以计算Euclidean distance：

mouse_x, mouse_y = pygame.mouse.get_pos()
for tree in trees:
    if pygame.mouse.get_pressed()[0] and tree.trunk.collidepoint((mouse_x, mouse_y)):
        print('clicked tree') # For testing purposes

        dx, dy = (mouse_x - x, mouse_y - y)
        if dx*dx + dy*dy <= 50*50:
            countdown = 3
            destroy_tree = tree