How to implement a particle mechanism

Question

How to implement a particle mechanism

So, I made a particle engine for smoke, and I am very pleased, I think it fits my game very well.
Now I have to implement it in my game, and I have a bit of a problem. I was wondering if anyone could explain how I will use my particle engine in my game.
I added both of my codes (for smoke and the game file) below.
I want the particles to be separated from the game files, but call it in my game.
In the end, I want to do more particle effects in the engine that I could name.

Can anyone help? It may take a little tweaking to work.

PARTICLE CODES:

import pygame,random
from pygame.locals import *

xmax = 1000    #width of window
ymax = 600     #height of window

class Smoke():
    def __init__(self, startx, starty, col):
        self.x = startx
        self.y = random.randint(0, starty)
        self.col = col
        self.sx = startx
        self.sy = starty

    def move(self):
        if self.y < 0:
            self.x = self.sx
            self.y = self.sy
        else:
            self.y -= 1
        self.x += random.randint(-1, 2)

def main():
    pygame.init()
    screen = pygame.display.set_mode((xmax,ymax))
    black = (0,0,0)
    grey = (145,145,145)
    light_grey = (192,192,192)
    dark_grey = (183, 183, 183)

    clock = pygame.time.Clock()

    particles = []
    for part in range(600):
        if part % 2 > 0: col = grey
        #elif part % 5 > 0: col = dark_grey
        elif part % 3 > 0: col = dark_grey
        else: col = light_grey
        particles.append( Smoke(0, 500, col) )

    exitflag = False
    while not exitflag:
        for event in pygame.event.get():
            if event.type == QUIT:
                exitflag = True
            elif event.type == KEYDOWN:
                if event.key == K_ESCAPE:
                    exitflag = True

        screen.fill(black)
        for p in particles:
            p.move()
            pygame.draw.circle(screen, p.col, (p.x, p.y), 15)

        pygame.display.flip()
        clock.tick(80)
    pygame.quit()

if __name__ == "__main__":
    main()

GAME CODE

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

levels = {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",],
             'enemies': [(9, 38)]},
             1: {'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                  PPPPPPPPPPP     PPPPPPP",
                    "PPP                         PPPP     PPPPPPP",
                    "PPP                         PPPP     PPPPPPP",
                    "PPP             PPPPPPPP    PPPP     PPPPPPP",
                    "PPP                                     PPPP",
                    "PPP                                     PPPP",
                    "PPP          PPPPP                      PPPP",
                    "PPP          P            PPPPPPPPPPPPPPPPPP",
                    "PPP          P    PPPPPPPPPPPPPPPPPPPPPPPPPP",
                    "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",
                    "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",
                    "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",
                    "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",
                    "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",],
             'enemies': [(9, 38), (18, 38), (15, 15)]}}

class Scene(object):
    def __init__(self):
        pass

    def render(self, screen):
        raise NotImplementedError

    def update(self):
        raise NotImplementedError

    def handle_events(self, events):
        raise NotImplementedError

class GameScene(Scene):
    def __init__(self, levelno):
        super(GameScene, self).__init__()
        self.bg = Surface((32,32))
        self.bg.convert()
        self.bg.fill(Color("#0094FF"))
        up = left = right = False
        self.entities = pygame.sprite.Group()
        self.player = Player(5, 40)
        self.player.scene = self
        self.platforms = []

        self.levelno = levelno

        levelinfo = levels[levelno]
        self.enemies = [Enemy(*pos) for pos in levelinfo['enemies']]

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

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

        self.camera = Camera(complex_camera, total_level_width, total_level_height)
        self.entities.add(self.player)
        for e in self.enemies:
            self.entities.add(e)

    def render(self, screen):
        for y in range(20):
            for x in range(25):
                screen.blit(self.bg, (x * 32, y * 32))

        for e in self.entities:
            screen.blit(e.image, self.camera.apply(e))

    def update(self):
        pressed = pygame.key.get_pressed()
        up, left, right = [pressed[key] for key in (K_UP, K_LEFT, K_RIGHT)]
        self.player.update(up, left, right, self.platforms)

        for e in self.enemies:
            e.update(self.platforms)

        self.camera.update(self.player)

    def exit(self):
        if self.levelno+1 in levels:
            self.manager.go_to(GameScene(self.levelno+1))
        else:
            self.manager.go_to(CustomScene("You win!"))

    def die(self):
        self.manager.go_to(CustomScene("You lose!"))

    def handle_events(self, events):
        for e in events:
            if e.type == KEYDOWN and e.key == K_ESCAPE:
                self.manager.go_to(TitleScene())

class CustomScene(object):

    def __init__(self, text):
        self.text = text
        super(CustomScene, self).__init__()
        self.font = pygame.font.SysFont('Arial', 56)

    def render(self, screen):
        # ugly! 
        screen.fill((0, 200, 0))
        text1 = self.font.render(self.text, True, (255, 255, 255))
        screen.blit(text1, (200, 50))

    def update(self):
        pass

    def handle_events(self, events):
        for e in events:
            if e.type == KEYDOWN:
                self.manager.go_to(TitleScene())

class TitleScene(object):

    def __init__(self):
        super(TitleScene, self).__init__()
        self.font = pygame.font.SysFont('Arial', 56)
        self.sfont = pygame.font.SysFont('Arial', 32)

    def render(self, screen):
        # ugly! 
        screen.fill((0, 200, 0))
        text1 = self.font.render('Crazy Game', True, (255, 255, 255))
        text2 = self.sfont.render('> press space to start <', True, (255, 255, 255))
        screen.blit(text1, (200, 50))
        screen.blit(text2, (200, 350))

    def update(self):
        pass

    def handle_events(self, events):
        for e in events:
            if e.type == KEYDOWN and e.key == K_SPACE:
                self.manager.go_to(GameScene(0))

class SceneMananger(object):
    def __init__(self):
        self.go_to(TitleScene())

    def go_to(self, scene):
        self.scene = scene
        self.scene.manager = self

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

    manager = SceneMananger()

    while running:
        timer.tick(60)

        if pygame.event.get(QUIT):
            running = False
            return
        manager.scene.handle_events(pygame.event.get())
        manager.scene.update()
        manager.scene.render(screen)
        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(x*32, y*32, 32, 32)

    def update(self, up, left, right, platforms):
        if self.rect.top > 1440 or self.rect.top < 0:
            self.scene.die()
        if self.rect.left > 1408 or self.rect.right < 0:
            self.scene.die()
        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
        if 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):
                    self.scene.exit()
                    return False
                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
        return True

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(x*32, y*32, 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 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

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 = Surface((32,32)) #makes blocks visible for building levels
        self.image.convert()
        self.rect = Rect(x, y, 32, 32)




if __name__ == "__main__":
    main()

+5

python refactoring pygame particle-system

user1758231 Feb 14 '13 at 10:35

source share

1

sloth · Accepted Answer · 2013-02-15T10:23:22+0000

! !

Smoke. , . , Particle , , :

class Particle():
    def __init__(self, col, size, *strategies):
        self.x, self.y = 0, 0
        self.col = col
        self.alive = 0
        self.strategies = strategies
        self.size = size

    def kill(self):
        self.alive = -1 # alive -1 means dead

    def move(self):
        for s in self.strategies:
            s(self)

. , ( ) __init__, move.

, , , , .

, , :

def ascending(speed):
    def _ascending(particle):
        particle.y -= speed
    return _ascending

- , , :

def kill_at(max_x, max_y):
    def _kill_at(particle):
        if particle.x < -max_x or particle.x > max_x or particle.y < -max_y or particle.y > max_y:
            particle.kill()
    return _kill_at

, ( ), , :

def age(amount):
    def _age(particle):
        particle.alive += amount
    return _age

, ( !), :

def fan_out(modifier):
    def _fan_out(particle):
        d = particle.alive / modifier
        d += 1
        particle.x += random.randint(-d, d)
    return _fan_out

! , , , :

def wind(direction, strength):
    def _wind(particle):
        if random.randint(0,100) < strength:
            particle.x += direction
    return _wind

, . . , .

: !

def smoke_machine():
    colors = {0: grey,
              1: dark_grey,
              2: light_grey}
    def create():
        for _ in xrange(random.choice([0,0,0,0,0,0,0,1,2,3])):
            behaviour = age(1), ascending(1), fan_out(400), wind(1, 15), kill_at(1000, 1000)
            p = Particle(colors[random.randint(0, 2)], random.randint(10, 15), *behaviour)
            yield p

    while True:
        yield create()

, , ? . , . , - , , create. , , 0 3 random.choice. , 0 70% 1, 2 3 10% .

. . , . , .

- .

, , :

>>> s=smoke_machine()
>>> list(next(s))
[]
>>> list(next(s))
[<particle.Particle instance at 0x02AD94B8>, <particle.Particle instance at 0x02
AD9030>]
>>> list(next(s))
[]
>>> list(next(s))
[]
>>> list(next(s))
[<particle.Particle instance at 0x02AD9030>]
>>> list(next(s))
[<particle.Particle instance at 0x02AD9418>, <particle.Particle instance at 0x02
AD93C8>]
>>> list(next(s))
[<particle.Particle instance at 0x02AD9030>]

, , , 3 .

? , :

class Emitter(object):
    def __init__(self, pos=(0, 0)):
        self.particles = []
        self.pos = pos
        self.factories = []

    def add_factory(self, factory, pre_fill=300):
        self.factories.append(factory)
        tmp = []
        for _ in xrange(pre_fill):
            n = next(factory)
            tmp.extend(n)
            for p in tmp:
                p.move()
        self.particles.extend(tmp)

    def update(self):
        for f in self.factories:
            self.particles.extend(next(f))

        for p in self.particles[:]:
            p.move()
            if p.alive == -1:
                self.particles.remove(p)

    def draw(self, screen, position_translater_func):
        for p in self.particles:
            target_pos = position_translater_func(map(sum, zip((p.x, p.y), self.pos)))
            pygame.draw.circle(screen, p.col, target_pos, int(p.size))

factory (, smoke_machine), , , self.particles, . :

factory add_factory, factory 300 ( - pre_fill) . , .

, , Emitter. , , , , , .

, Emitter . GameScene self.emitter Emitter smoke_machine factory.

render

for e in self.emitter:
    e.draw(screen, self.camera.apply)

update

for e in self.emitter:
   e.update()

!

:

game.py

, 30000 : -)

import pygame
from pygame import *
from particle import Emitter, smoke_machine
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

levels = {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    S      PPPPPPPPPPPPPPPPPP",],
             'enemies': [(9, 38)]},
             1: {'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                  PPPPPPPPPPP     PPPPPPP",
                    "PPP                         PPPP     PPPPPPP",
                    "PPP                         PPPP     PPPPPPP",
                    "PPP             PPPPPPPP    PPPP     PPPPPPP",
                    "PPP                                     PPPP",
                    "PPP                                     PPPP",
                    "PPP          PPPPP                      PPPP",
                    "PPP          P            PPPPPPPPPPPPPPPPPP",
                    "PPP          P    PPPPPPPPPPPPPPPPPPPPPPPPPP",
                    "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",
                    "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",
                    "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",
                    "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",
                    "PPPPPPPPPPPPPPP           PPPPPPPPPPPPPPPPPP",],
             'enemies': [(9, 38), (18, 38), (15, 15)]}}

...

class GameScene(Scene):
    def __init__(self, levelno):
        super(GameScene, self).__init__()
        self.bg = Surface((32,32))
        self.bg.convert()
        self.bg.fill(Color("#0094FF"))
        up = left = right = False
        self.entities = pygame.sprite.Group()
        self.player = Player(5, 40)
        self.player.scene = self
        self.platforms = []

        self.levelno = levelno

        levelinfo = levels[levelno]
        self.enemies = [Enemy(*pos) for pos in levelinfo['enemies']]

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

        self.emitter = []

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

        self.camera = Camera(complex_camera, total_level_width, total_level_height)
        self.entities.add(self.player)
        for e in self.enemies:
            self.entities.add(e)

    def render(self, screen):
        for y in range(20):
            for x in range(25):
                screen.blit(self.bg, (x * 32, y * 32))

        for e in self.emitter:
            e.draw(screen, self.camera.apply)

        for e in self.entities:
            screen.blit(e.image, self.camera.apply(e))

    def update(self):
        for e in self.emitter:
            e.update()

        pressed = pygame.key.get_pressed()
        up, left, right = [pressed[key] for key in (K_UP, K_LEFT, K_RIGHT)]
        self.player.update(up, left, right, self.platforms)

        for e in self.enemies:
            e.update(self.platforms)

        self.camera.update(self.player)

    def exit(self):
        if self.levelno+1 in levels:
            self.manager.go_to(GameScene(self.levelno+1))
        else:
            self.manager.go_to(CustomScene("You win!"))

    def die(self):
        self.manager.go_to(CustomScene("You lose!"))

    def handle_events(self, events):
        for e in events:
            if e.type == KEYDOWN and e.key == K_ESCAPE:
                self.manager.go_to(TitleScene())

...

if __name__ == "__main__":
    main()

particle.py

import pygame,random

def ascending(speed):
    def _ascending(particle):
        particle.y -= speed
    return _ascending

def kill_at(max_x, max_y):
    def _kill_at(particle):
        if particle.x < -max_x or particle.x > max_x or particle.y < -max_y or particle.y > max_y:
            particle.kill()
    return _kill_at

def age(amount):
    def _age(particle):
        particle.alive += amount
    return _age

def fan_out(modifier):
    def _fan_out(particle):
        d = particle.alive / modifier
        d += 1
        particle.x += random.randint(-d, d)
    return _fan_out

def wind(direction, strength):
    def _wind(particle):
        if random.randint(0,100) < strength:
            particle.x += direction
    return _wind

class Particle():
    def __init__(self, col, size, *strategies):
        self.x, self.y = 0, 0
        self.col = col
        self.alive = 0
        self.strategies = strategies
        self.size = size

    def kill(self):
        self.alive = -1 # alive -1 means dead

    def move(self):
        for s in self.strategies:
            s(self)        

black = (0,0,0)
grey = (145,145,145)
light_grey = (192,192,192)
dark_grey = (183, 183, 183)

def smoke_machine():
    colors = {0: grey,
              1: dark_grey,
              2: light_grey}
    def create():
        for _ in xrange(random.choice([0,0,0,0,0,0,0,1,2,3])):
            behaviour = ascending(1), kill_at(1000, 1000), fan_out(400), wind(1, 15), age(1)
            p = Particle(colors[random.randint(0, 2)], random.randint(10, 15), *behaviour)
            yield p

    while True:
        yield create()

class Emitter(object):
    def __init__(self, pos=(0, 0)):
        self.particles = []
        self.pos = pos
        self.factories = []

    def add_factory(self, factory, pre_fill=300):
        self.factories.append(factory)
        tmp = []
        for _ in xrange(pre_fill):
            n = next(factory)
            tmp.extend(n)
            for p in tmp:
                p.move()
        self.particles.extend(tmp)

    def update(self):
        for f in self.factories:
            self.particles.extend(next(f))

        for p in self.particles[:]:
            p.move()
            if p.alive == -1:
                self.particles.remove(p)

    def draw(self, screen, position_translater_func):
        for p in self.particles:
            target_pos = position_translater_func(map(sum, zip((p.x, p.y), self.pos)))
            pygame.draw.circle(screen, p.col, target_pos, int(p.size))

. , , , , factory.

, , SRP, factory - .

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, ,

def grow(amount):
    def _grow(particle):
        if random.randint(0,100) < particle.alive / 20:
            particle.size += amount
    return _grow

grow(0.5) smoke_machine

, .

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P.S.: ( ) . numpy, itertools, psyco pygame.surfarray random .

How to implement a particle mechanism

!

:

game.py

particle.py

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