python - Pygame - 实体移动限制 - 碰撞检测

Question

好吧，我有一个实体在两个位置之间来回走动，现在是如下所示的像素位置:

        if self.rect.left == 96:
            self.right_dis = False
        if self.rect.right == 480:
            self.right_dis = True
        if not self.right_dis:
            self.xVel = 2
        if self.right_dis:
            self.xVel = -2

我的问题是，有没有办法指定它在平台上移动直到到达平台末端然后掉头？这样它就可以来回移动，而无需我指定哪些像素位置之间？以下是我的其余代码和视频:

import pygame
from pygame import *

WIN_WIDTH = 1120 - 320
WIN_HEIGHT = 960 - 320
HALF_WIDTH = int(WIN_WIDTH / 2)
HALF_HEIGHT = int(WIN_HEIGHT / 2)

DISPLAY = (WIN_WIDTH, WIN_HEIGHT)
DEPTH = 0
FLAGS = 0
CAMERA_SLACK = 30

def main():
    global level
    pygame.init()
    screen = pygame.display.set_mode(DISPLAY, FLAGS, DEPTH)
    pygame.display.set_caption("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
    timer = pygame.time.Clock()
    level = 0

    bg = Surface((32,32))
    bg.convert()
    bg.fill(Color("#0094FF"))

    up = left = right = False
    entities = pygame.sprite.Group()
    player = Player(32, 32)
    enemy = Enemy(32,32)
    platforms = []

    x = 0
    y = 0

    if level == 0:
        level = [
            "                                            ",
            "                                            ",
            "                                            ",
            "                                            ",
            "                                            ",
            "                                            ",
            "                                            ",
            "                                            ",
            "                                            ",
            "                                            ",
            "                                            ",
            "                                            ",
            "                                            ",
            "                                            ",
            "                                            ",
            "                                         E  ",
            "                            PPPPPPPPPPPPPPPP",
            "                            PPPPPPPPPPPPPPPP",
            "                            PPPPPPPPPPPPPPPP",
            "               PPPPP        PPPPPPPPPPPPPPPP",
            "                            PPPPPPPPPPPPPPPP",
            "                            PPPP           P",
            "                            PPPP           P",
            "                            PPPP     PPPPPPP",
            "                      PPPPPPPPPP     PPPPPPP",
            "                            PPPP     PPPPPPP",
            "       PPPP                 PPPP     PPPPPPP",
            "                            PPPP     PPPPPPP",
            "                            PPPP     PPPPPPP",
            "                            PPPP     PPPPPPP",
            "PPPPP                       PPPP     PPPPPPP",
            "PPP                         PPPP     PPPPPPP",
            "PPP                         PPPP     PPPPPPP",
            "PPP                         PPPP     PPPPPPP",
            "PPP         PPPPP           PPPP     PPPPPPP",
            "PPP                                     PPPP",
            "PPP                                     PPPP",
            "PPP                                     PPPP",
            "PPP                       PPPPPPPPPPPPPPPPPP",
            "PPP                       PPPPPPPPPPPPPPPPPP",
            "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",
            "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",
            "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",
            "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",
            "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",]

        #background = pygame.image.load("Untitled.png")


    total_level_width = len(level[0]) * 32
    total_level_height = len(level) * 32

    # build the level
    for row in level:
        for col in row:
            if col == "P":
                p = Platform(x, y)
                platforms.append(p)
                entities.add(p)
            if col == "E":
                e = ExitBlock(x, y)
                platforms.append(e)
                entities.add(e)
            x += 32
        y += 32
        x = 0

    camera = Camera(complex_camera, total_level_width, total_level_height)
    entities.add(player)
    entities.add(enemy)

    while 1:
        timer.tick(60)

        for e in pygame.event.get():
            if e.type == QUIT: raise SystemExit, "QUIT"
            if e.type == KEYDOWN and e.key == K_ESCAPE:
                raise SystemExit, "ESCAPE"

            if e.type == KEYDOWN and e.key == K_UP:
                up = True
            if e.type == KEYDOWN and e.key == K_LEFT:
                left = True
            if e.type == KEYDOWN and e.key == K_RIGHT:
                right = True

            if e.type == KEYUP and e.key == K_UP:
                up = False
            if e.type == KEYUP and e.key == K_LEFT:
                left = False
            if e.type == KEYUP and e.key == K_RIGHT:
                right = False

        # draw background
        for y in range(20):
            for x in range(25):
                screen.blit(bg, (x * 32, y * 32))

        # draw background
        #screen.blit(background, camera.apply((0,0)))
        #draw entities
        for e in entities:
            screen.blit(e.image, camera.apply(e))
        # update player, update camera, and refresh
        player.update(up, left, right, platforms)
        enemy.update(platforms)
        camera.update(player)
        pygame.display.flip()

class Camera(object):
    def __init__(self, camera_func, width, height):
        self.camera_func = camera_func
        self.state = Rect(0, 0, width, height)

    def apply(self, target):
        try:
            return target.rect.move(self.state.topleft)
        except AttributeError:
            return map(sum, zip(target, self.state.topleft))

    def update(self, target):
        self.state = self.camera_func(self.state, target.rect)

def complex_camera(camera, target_rect):
    l, t, _, _ = target_rect
    _, _, w, h = camera
    l, t, _, _ = -l + HALF_WIDTH, -t +HALF_HEIGHT, w, h

    l = min(0, l)                           # stop scrolling left
    l = max(-(camera.width - WIN_WIDTH), l)   # stop scrolling right
    t = max(-(camera.height-WIN_HEIGHT), t) # stop scrolling bottom

    return Rect(l, t, w, h)

class Entity(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)

class Player(Entity):
    def __init__(self, x, y):
        Entity.__init__(self)
        self.xvel = 0
        self.yvel = 0
        self.onGround = False
        self.image = Surface((32,32))
        self.image.fill(Color("#0000FF"))
        self.image.convert()
        self.rect = Rect(200, 1200, 32, 32)


    def update(self, up, left, right, platforms):
        if self.rect.top > 1440 or self.rect.top < 0:
            main()
        if self.rect.left > 1408 or self.rect.right < 0:
            main()
        if up:
            if self.onGround:
                self.yvel = 0
                self.yvel -= 10 # only jump if on the ground
        if left:
            self.xvel = -10
        if right:
            self.xvel = 10
        if not self.onGround:
            self.yvel += 0.3 # only accelerate with gravity if in the air
            if self.yvel > 80: self.yvel = 80 # max falling speed
        if not(left or right):
            self.xvel = 0

        self.rect.left += self.xvel # increment in x direction
        self.collide(self.xvel, 0, platforms) # do x-axis collisions
        self.rect.top += self.yvel # increment in y direction
        self.onGround = False; # assuming we're in the air
        self.collide(0, self.yvel, platforms) # do y-axis collisions

    def collide(self, xvel, yvel, platforms):
        for p in platforms:
            if pygame.sprite.collide_rect(self, p):
                if isinstance(p, ExitBlock):
                    pygame.event.post(pygame.event.Event(QUIT))
                if xvel > 0: self.rect.right = p.rect.left
                if xvel < 0: self.rect.left = p.rect.right
                if yvel > 0:
                    self.rect.bottom = p.rect.top
                    self.onGround = True
                if yvel < 0:
                    self.rect.top = p.rect.bottom


class Enemy(Entity):
    def __init__(self, x, y):
        Entity.__init__(self)
        self.yVel = 0
        self.xVel = 0
        self.image = Surface((32,32))
        self.image.fill(Color("#00FF00"))
        self.image.convert()
        self.rect = Rect(300, 1200, 32, 32)
        self.onGround = False
        self.right_dis = False

    def update(self, platforms):
        if not self.onGround:
            self.yVel += 0.3

        if self.rect.left == 96:
            self.right_dis = False
        if self.rect.right == 480:
            self.right_dis = True
        if not self.right_dis:
            self.xVel = 2
        if self.right_dis:
            self.xVel = -2

        self.rect.left += self.xVel # increment in x direction
        self.collide(self.xVel, 0, platforms) # do x-axis collisions
        self.rect.top += self.yVel # increment in y direction
        self.onGround = False; # assuming we're in the air
        self.collide(0, self.yVel, platforms) # do y-axis collisions

    def collide(self, xVel, yVel, platforms):
        for p in platforms:
            if pygame.sprite.collide_rect(self, p):
                if xVel > 0: self.rect.right = p.rect.left
                if xVel < 0: self.rect.left = p.rect.right
                if yVel > 0:
                    self.rect.bottom = p.rect.top
                    self.onGround = True
                if yVel < 0:
                    self.rect.top = p.rect.bottom

class Platform(Entity):
    def __init__(self, x, y):
        Entity.__init__(self)
        #self.image = Surface([32, 32], pygame.SRCALPHA, 32) #makes blocks invisible for much better artwork
        self.image = Surface((32,32)) #makes blocks visible for building levels
        self.image.convert()
        self.rect = Rect(x, y, 32, 32)

    def update(self):
        pass

class ExitBlock(Platform):
    def __init__(self, x, y):
        Platform.__init__(self, x, y)
        self.image = pygame.image.load("end.png")




if __name__ == "__main__":
    main()

Answer 1

获取实体的矩形。

如果向右移动，则取矩形的右下点，将其向右移动一个像素并向下移动一个像素，然后检查是否这样点与平台碰撞。如果没有，您就知道它到达了平台的末端。

如果它向左移动，您只需获取左下点并将其向左移动一个像素并向下移动一个像素。

<小时/>

“移动”一个点(如果它是一个Tuple或List)的一个简单方法是使用map-sum-zip技巧:

>>> point = (8,10)
>>> to_move = (1,1)
>>> map(sum, zip(point, to_move))
[9, 11]
>>> to_move = (-1,1)
>>> map(sum, zip(point, to_move))
[7, 11]
>>>

<小时/>

只是为了好玩，这是一个完整的示例(请注意注释):

class Enemy(Entity):
    def __init__(self, x, y):
        Entity.__init__(self)
        self.yVel = 0
        self.xVel = 2 # start moving immediately
        self.image = Surface((32,32))
        self.image.fill(Color("#00FF00"))
        self.image.convert()
        self.rect = Rect(300, 1200, 32, 32)
        self.onGround = False

    def update(self, platforms):
        if not self.onGround:
            self.yVel += 0.3

        # no need for right_dis to be a member of the class,
        # since we know we are moving right if self.xVel > 0
        right_dis = self.xVel > 0

        # create a point at our left (or right) feet 
        # to check if we reached the end of the platform
        m = (1, 1) if right_dis else (-1, 1)
        p = self.rect.bottomright if right_dis else self.rect.bottomleft
        fp = map(sum, zip(m, p))

        # if there's no platform in front of us, change the direction
        collide = any(p for p in platforms if p.rect.collidepoint(fp))
        if not collide:
            self.xVel *= -1

        self.rect.left += self.xVel # increment in x direction
        self.collide(self.xVel, 0, platforms) # do x-axis collisions
        self.rect.top += self.yVel # increment in y direction
        self.onGround = False; # assuming we're in the air
        self.collide(0, self.yVel, platforms) # do y-axis collisions

    def collide(self, xVel, yVel, platforms):
        for p in platforms:
            if pygame.sprite.collide_rect(self, p):
                if xVel > 0: 
                    self.rect.right = p.rect.left
                    self.xVel *= -1 # hit wall, so change direction
                if xVel < 0: 
                    self.rect.left = p.rect.right
                    self.xVel *= -1 # hit wall, so change direction
                if yVel > 0:
                    self.rect.bottom = p.rect.top
                    self.onGround = True
                if yVel < 0:
                    self.rect.top = p.rect.bottom