python - Pygame问题: how to execute conditional on collision?

Question

我在 pygame 和碰撞检测方面遇到问题。我编写的程序应该在单击时绘制一个矩形，在鼠标悬停时更改阿尔法。这两个有效。但我还尝试实现仅在矩形已存在/鼠标位于现有矩形上方时才执行的功能。

现在，我试图让程序在检测到碰撞时不绘制新的标记/矩形，但我想不出一种方法来做到这一点...我在代码示例中尝试的方法不起作用，它只返回最后添加的标记的碰撞状态...

我两个月前才开始编码，所以也许我错过了一些关于 python 的基本想法。我试图在不失去其功能要点的情况下发布尽可能少的代码。抱歉，如果还是太长。

那么有没有办法获得我想要的功能？

感谢您的帮助!

import pygame


pygame.init()

clock = pygame.time.Clock()
clock.tick(20)

BLACK = (0, 0, 0)
RED = (255, 0, 0)
GREEN = (0, 255, 0)

screen = pygame.display.set_mode((500, 500))
running = True


LEFT = 1



class Marker(pygame.sprite.Sprite):

  """
used to draw the marker at a given position
  """

  def __init__(self, x, y, key, function):
    pygame.sprite.Sprite.__init__(self)

    self.image = pygame.Surface((50, 50))
    self.image.fill(RED)
    self.image.set_alpha(50)

    self.rect = self.image.get_rect()
    self.rect.x = x
    self.rect.y = y

    self.function = function

  def check_click(self, mouse):
    if self.rect.collidepoint(mouse):
      self.image.set_alpha(200)
      return True

    if not self.rect.collidepoint(mouse):
      self.image.set_alpha(50)


  def collide_check(self, mouse):
    return self.rect.collidepoint(mouse)

  def get_function(self):
    return self.function


class Connections:

  def __init__(self):
    self.switch = False
    self.con_dict = {}
    self.key_dict = []

  def generate_key(self, position): #generates a dictionary key out of mouse position
    position_x, position_y = position
    instance_name = str(position_x) + str(position_y)
    return instance_name

  def add_entrance_or_exit(self, position): 
#sets marker/rectangle at mouse position(depending on switch state)
    if not self.switch:
      key = self.generate_key(position)
      self.key_dict.append(key)
      self.con_dict[key] = position
      pos_x, pos_y = position
      new_key = key + "_entrance"
      new_key = Marker(pos_x, pos_y, key, "entrance")
      all_sprites.add(new_key)
      self.switch = True
    else:
      key = self.key_dict[-1]
      old_pos = self.con_dict[key]
      pos_x, pos_y = position
      new_key = key + "_exit"
      new_key = Marker(pos_x, pos_y, key, "exit")
      all_sprites.add(new_key)
      self.con_dict[key] = [old_pos, position]
      self.switch = False


all_sprites = pygame.sprite.Group()

connections = Connections()

running = True


while running:
  collide = None
  for s in all_sprites:
    mouse_pos = pygame.mouse.get_pos()
    s.check_click(mouse_pos)
    collide = s.check_click(mouse_pos)

  for event in pygame.event.get():
    if event.type == pygame.QUIT:
      running = False
    elif event.type == pygame.MOUSEBUTTONDOWN and event.button == LEFT:
      if collide == None:
        mouse = pygame.mouse.get_pos()
        connections.add_entrance_or_exit(mouse)

  screen.fill(BLACK)
  all_sprites.update()
  all_sprites.draw(screen)
  pygame.display.update()


pygame.quit()

Answer 1

由于 check_click 更改图像的 Alpha channel ，因此必须为每个 Sprite (s) 调用它。 collide 应该是一个 bool 值(True 或 False)，并且必须设置 if s.check_click(mouse_pos)评估True:

running = True
while running:

  mouse_pos = pygame.mouse.get_pos()

  collide = False
  for s in all_sprites:
    if s.check_click(mouse_pos):
      collide = True

  for event in pygame.event.get():
    if event.type == pygame.QUIT:
      running = False
    elif event.type == pygame.MOUSEBUTTONDOWN and event.button == LEFT:
      if not collide:
        mouse = pygame.mouse.get_pos()
        connections.add_entrance_or_exit(mouse)

请注意，这可以通过创建正在碰撞的 Sprite 列表并验证该列表是否包含不 any 来进一步简化。元素:

running = True
while running:

  mouse_pos = pygame.mouse.get_pos()
  collide_list = [s for s in all_sprites if s.check_click(mouse_pos)]

  for event in pygame.event.get():
    if event.type == pygame.QUIT:
      running = False
    elif event.type == pygame.MOUSEBUTTONDOWN and event.button == LEFT:
      if not any(collide_list):
        mouse = pygame.mouse.get_pos()
        connections.add_entrance_or_exit(mouse)

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此外，评估鼠标是否位于矩形上是不够的，您必须评估在鼠标位置绘制的矩形是否与任何其他矩形相交 colliderect() 。图像的 Alpha channel 必须根据鼠标位置进行设置 collidepoint() :
(请注意，collidepoint 分别 colliderect() 返回 True 或 False)

class Marker(pygame.sprite.Sprite):
  # [...]

  def check_click(self, mouse):
    self.image.set_alpha(200 if self.rect.collidepoint(mouse) else 50)
    return self.rect.colliderect((*mouse, 50, 50)) 

<小时/>