我试图让一个侧卷轴使用pygame，我一直在研究以下程序，但需要澄清几点：
#! /usr/bin/python
import pygame, platform
platform.architecture()
from pygame import *
WIN_WIDTH = 800
WIN_HEIGHT = 640
HALF_WIDTH = int(WIN_WIDTH / 2)
HALF_HEIGHT = int(WIN_HEIGHT / 2)
DISPLAY = (WIN_WIDTH, WIN_HEIGHT)
DEPTH = 32
FLAGS = 0
CAMERA_SLACK = 30
def main():
global cameraX, cameraY
pygame.init()
screen = pygame.display.set_mode(DISPLAY, FLAGS, DEPTH)
pygame.display.set_caption("Use arrows to move!")
timer = pygame.time.Clock()
up = down = left = right = running = False
bg = Surface((32,32))
bg.convert()
bg.fill(Color("#000000"))
entities = pygame.sprite.Group()
player = Player(32, 32)
platforms = []
x = y = 0
level = [
"PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP",
"P P",
"P P",
"P P",
"P PPPPPPPPPPP P",
"P P",
"P P",
"P P",
"P PPPPPPPP P",
"P P",
"P PPPPPPP P",
"P PPPPPP P",
"P P",
"P PPPPPPP P",
"P P",
"P PPPPPP P",
"P P",
"P PPPPPPPPPPP P",
"P P",
"P PPPPPPPPPPP P",
"P P",
"P P",
"P P",
"P P",
"PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP",]
# 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
total_level_width = len(level[0])*32
total_level_height = len(level)*32
#COMPLEX_CAMERA???
camera = Camera(complex_camera, total_level_width, total_level_height)
entities.add(player)
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_DOWN:
down = 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 == KEYDOWN and e.key == K_SPACE:
running = True
if e.type == KEYUP and e.key == K_UP:
up = False
if e.type == KEYUP and e.key == K_DOWN:
down = False
if e.type == KEYUP and e.key == K_RIGHT:
right = False
if e.type == KEYUP and e.key == K_LEFT:
left = False
# draw background
for y in range(32):
for x in range(32):
screen.blit(bg, (x * 32, y * 32))
camera.update(player)
# update player, draw everything else
player.update(up, down, left, right, running, platforms)
for e in entities:
screen.blit(e.image, camera.apply(e))
pygame.display.update()
class Camera(object):
#CAMERA_FUNC???
def __init__(self, camera_func, width, height):
self.camera_func = camera_func
self.state = Rect(0, 0, width, height)
def apply(self, target):
return target.rect.move(self.state.topleft)
def update(self, target):
self.state = self.camera_func(self.state, target.rect)
def simple_camera(camera, target_rect):
#UNDERLINE???
l, t, _, _ = target_rect
_, _, w, h = camera
return Rect(-l+HALF_WIDTH, -t+HALF_HEIGHT, w, h)
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 at the left edge
l = max(-(camera.width-WIN_WIDTH), l) # stop scrolling at the right edge
t = max(-(camera.height-WIN_HEIGHT), t) # stop scrolling at the bottom
t = min(0, t) # stop scrolling at the top
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(x, y, 32, 32)
def update(self, up, down, left, right, running, platforms):
if up:
# only jump if on the ground
if self.onGround: self.yvel -= 10
if down:
pass
if running:
self.xvel = 12
if left:
self.xvel = -8
if right:
self.xvel = 8
if not self.onGround:
# only accelerate with gravity if in the air
self.yvel += 0.3
# max falling speed
if self.yvel > 100: self.yvel = 100
if not(left or right):
self.xvel = 0
# increment in x direction
self.rect.left += self.xvel
# do x-axis collisions
self.collide(self.xvel, 0, platforms)
# increment in y direction
self.rect.top += self.yvel
# assuming we're in the air
self.onGround = False;
# do y-axis collisions
self.collide(0, self.yvel, platforms)
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
print "collide right"
if xvel < 0:
self.rect.left = p.rect.right
print "collide left"
if yvel > 0:
self.rect.bottom = p.rect.top
self.onGround = True
self.yvel = 0
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))
self.image.convert()
self.image.fill(Color("#DDDDDD"))
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.fill(Color("#0033FF"))
if __name__ == "__main__":
main()
首先，这行代码中的'complex_camera'是什么：
camera = Camera(complex_camera, total_level_width, total_level_height)
complex_camera是对函数的调用吗？如果是这样，是不是函数'complex_camera'期望相机的矩形和播放器的矩形？为什么没有括号，也没有传递给函数的参数？
也许在相关的说明中，在Camera的构造函数中找到的代码块中：
self.camera_func = camera_func
为什么在程序中从未使用过'camera_func'属性？
我的最后一个问题出现在以下代码块中：
def simple_camera(camera, target_rect):
l, t, _, _ = target_rect
_, _, w, h = camera
return Rect(-l+HALF_WIDTH, -t+HALF_HEIGHT, w, h)
你能解释一下下划线的含义吗？我先发出一条感谢信，以便为我清理这些问题。
答案 0 :(得分：1)
1：complex_camera是一个返回矩形的函数
并且它不是一个电话，它只是将该功能传递给Camera对象。
self.camera_func = camera_func
self.camera_func将是complex_camera。
这样，当调用update的{{1}}方法时：
Camera def update(self, target):
self.state = self.camera_func(self.state, target.rect)
将等于使用self.state和complex_camera参数调用的self.state函数的输出
target.rect2：
self.state = complex_camera(self.state, target.rect)
def simple_camera(camera, target_rect):
l, t, _, _ = target_rect
（应该是）一个4元素的元组
target_rect这一行告诉python＆＃34; unpack＆＃34;元组。
l, t, _, _ = target_rect
将等于元组的第一个元素（在这种情况下，＆＃34; left＆＃34;属性为rect）
l将等于第二个。（在这种情况下，＆＃34; top＆＃34; rect的属性）
t只是意味着没有考虑这个属性;但由于预期_是一个4元素元组，因此解包它应该提供4个变量，而不仅仅是2个。
例如：
target_rect现在my_tuple = ('a', 'b', 'c')
first, second, third = my_tuple
如果您只想使用第一个和第三个，您将会这样做：
first = 'a', second = 'b', third = 'c'