pythonpygamecollision-detection
Pygame - Entity movement limitations - collison detection
Ok so I have an entity that walks back and forth between two positions that right now are pixel locations shown below:
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
My question is, is there a way to specify while its on a platform move till it reaches the end of the platform then turn around? So that it moves back and forth without me having to specify between what pixel locations? Below is the rest of my code and a video:
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()
Solution
Take the Rect of your Entity.
If it is moving to the right, take the bottomright point of the Rect, move it one pixel to the right and one pixel down, and then check if this point collides with a Platform. If it does not, you know it reached the end of the platform.
If it is moving left, you just take the bottomleft point and move it one pixel to the left and one down.
An easy way to "move" a point (if it's a Tuple or List) is to use the map-sum-zip trick:
>>> 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]
>>>
Just for fun, here's a complete example (note the comments):
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
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