Pygame问题:精灵在树上奔跑

Question

我正在创造一款玩家可以探索地形的游戏，总是随机的&计算机生成的。作为精灵的玩家应该只在草地上奔跑，而不应该跑到树上。换句话说，玩家只能在草地上奔跑。

然而，尽管调试了几个小时，玩家仍然可以在树上跑，这是非常烦人的。

import pygame, player # the module where the Player class is defined
import block # the module where the Block class is  defined
...
#setting varibles, player, ...
run = True
clock = pygame.time.Clock()
create_world() # create the map of the world
while run:
    clock.tick(30)
    hit = pygame.sprite.spritecollide(player, blocks, False)
    location = player.rect.centerx # defined to use as return spot in case of tree
    # player is player.Player instance, blocks is group of all the blocks
    # the block.Block class has an attribute called 'type'; grass = 'block'
    # tree = 'tree'
    for e in pygame.event.get():
        if e.type == pygame.QUIT:
            run = False
        if e.type == pygame.KEYDOWN:
            if e.key == pygame.K_UP:
                speed = [-30, 0] # the varible to update player's location
                if hit[0].type == tree: # if hit tree
                    player.rect.centerx = location
                ...
        if e.type == pygame.KEYUP:
            reset_speed() # speed = [0, 0], to prevent constant movement
    player.update(speed) # update the player
    reset_speed() # not really useful
    render_world() # blit the world & player
pygame.quit()

if hit[0].type == 'tree': ...应该起作用，但它没有。为什么?

Answer 1

所以，为了帮助你自己，循环中的标准处理是先移动，然后处理碰撞，这样你就可以知道之前的位置和碰撞的位置。

在你的当前循环中，玩家可能会撞到一棵树，但只是移动到相同的位置。

一步一步地读取循环，然后试试:

。

 loop N:
  hit returns []
  location is set to (posN)
  speed is set
  player moves to (posN+1)
 loopN+1:
  hit returns [tree]
  location is set to (posN+1)
  speed is set
  player is reset to "location", but that is just (posN+1)
  player moves to (posN+2)

等等。从这里，希望你能看到它正在工作，只是不像你期望的那样，我可以挖出那句关于计算机总是正确的老话

解决方案:

稍微重写一下，考虑先处理移动，然后在循环中检查碰撞，这样会更容易理解。