http://eyehere.net/2011/python-pygame-novice-professional-index/

FSM(Finite-state machine)的嚴(yán)格定義，需要state和action和轉(zhuǎn)移函數(shù)都是確定性的输虱，也就是說颜启，必須要在完全把握所有交互可能性的時(shí)候榔幸，限定一個(gè)有限的交互狀態(tài)豪诲、交互動(dòng)作和轉(zhuǎn)移函數(shù)霉囚。

使用場(chǎng)景: 根據(jù)上面的定義就可以知道FSM在使用前必須已經(jīng)確定了所有的狀態(tài),所有的狀態(tài)轉(zhuǎn)移情況

可以這樣簡單的理解生活中但凡有流程性質(zhì)的東西都可以使用狀態(tài)機(jī)來處理

class State(object):
    def __init__(self, name):
        self.name = name
    def do_actions(self):
        pass

    def check_conditions(self):
        pass

    def entry_actions(self):
        pass

    def exit_actions(self):
        pass


class StateMachine(object):
    def __init__(self):
        self.states = {}
        self.active_state = None

    def add_state(self, state):
        self.states[state.name] = state

    def main_task(self):
        if self.active_state is None:
            return
        self.active_state.do_actions()
        new_state_name = self.active_state.check_conditions()
        if new_state_name is not None:
            self.set_state(new_state_name)

    def set_state(self, new_state_name):
        if self.active_state is not None:
            self.active_state.exit_actions()
        self.active_state = self.states[new_state_name]
        self.active_state.entry_actions()

上面是狀態(tài)機(jī)抽象模型
懶得寫 直接看別人寫好的吧.(上面鏈接教程 index_16)

SCREEN_SIZE = (640, 480)
NEST_POSITION = (320, 240)
ANT_COUNT = 20
NEST_SIZE = 100.
 
import pygame
from pygame.locals import *
 
from random import randint, choice
from gameobjects.vector2 import Vector2
 
class State(object):
    def __init__(self, name):
        self.name = name
    def do_actions(self):
        pass
    def check_conditions(self):
        pass
    def entry_actions(self):
        pass
    def exit_actions(self):
        pass        
 
class StateMachine(object):
    def __init__(self):
        self.states = {}
        self.active_state = None
 
    def add_state(self, state):
        self.states[state.name] = state
 
    def think(self):
        if self.active_state is None:
            return
        self.active_state.do_actions()
        new_state_name = self.active_state.check_conditions()
        if new_state_name is not None:
            self.set_state(new_state_name)
 
    def set_state(self, new_state_name):
        if self.active_state is not None:
            self.active_state.exit_actions()
        self.active_state = self.states[new_state_name]
        self.active_state.entry_actions()
 
class World(object):
    def __init__(self):
        self.entities = {}
        self.entity_id = 0
        self.background = pygame.surface.Surface(SCREEN_SIZE).convert()
        self.background.fill((255, 255, 255))
        pygame.draw.circle(self.background, (200, 255, 200), NEST_POSITION, int(NEST_SIZE))
 
    def add_entity(self, entity):
        self.entities[self.entity_id] = entity
        entity.id = self.entity_id
        self.entity_id += 1
 
    def remove_entity(self, entity):
        del self.entities[entity.id]
 
    def get(self, entity_id):
        if entity_id in self.entities:
            return self.entities[entity_id]
        else:
            return None
 
    def process(self, time_passed):
        time_passed_seconds = time_passed / 1000.0
        for entity in self.entities.values():
            entity.process(time_passed_seconds)
 
    def render(self, surface):
        surface.blit(self.background, (0, 0))
        for entity in self.entities.itervalues():
            entity.render(surface)
 
    def get_close_entity(self, name, location, range=100.):
        location = Vector2(*location)
        for entity in self.entities.itervalues():
            if entity.name == name:
                distance = location.get_distance_to(entity.location)
                if distance < range:
                    return entity
        return None
 
class GameEntity(object):
 
    def __init__(self, world, name, image):
 
        self.world = world
        self.name = name
        self.image = image
        self.location = Vector2(0, 0)
        self.destination = Vector2(0, 0)
        self.speed = 0.
        self.brain = StateMachine()
        self.id = 0
 
    def render(self, surface):
        x, y = self.location
        w, h = self.image.get_size()
        surface.blit(self.image, (x-w/2, y-h/2))   
 
    def process(self, time_passed):
        self.brain.think()
        if self.speed > 0. and self.location != self.destination:
            vec_to_destination = self.destination - self.location
            distance_to_destination = vec_to_destination.get_length()
            heading = vec_to_destination.get_normalized()
            travel_distance = min(distance_to_destination, time_passed * self.speed)
            self.location += travel_distance * heading
 
class Leaf(GameEntity):
    def __init__(self, world, image):
        GameEntity.__init__(self, world, "leaf", image)
 
class Spider(GameEntity):
    def __init__(self, world, image):
        GameEntity.__init__(self, world, "spider", image)
        self.dead_image = pygame.transform.flip(image, 0, 1)
        self.health = 25
        self.speed = 50. + randint(-20, 20)
 
    def bitten(self):
        self.health -= 1
        if self.health <= 0:
            self.speed = 0.
            self.image = self.dead_image
        self.speed = 140.
 
    def render(self, surface):
        GameEntity.render(self, surface)
        x, y = self.location
        w, h = self.image.get_size()
        bar_x = x - 12
        bar_y = y + h/2
        surface.fill( (255, 0, 0), (bar_x, bar_y, 25, 4))
        surface.fill( (0, 255, 0), (bar_x, bar_y, self.health, 4))
 
    def process(self, time_passed):
        x, y = self.location
        if x > SCREEN_SIZE[0] + 2:
            self.world.remove_entity(self)
            return
        GameEntity.process(self, time_passed)
 
class Ant(GameEntity):
    def __init__(self, world, image):
        GameEntity.__init__(self, world, "ant", image)
        exploring_state = AntStateExploring(self)
        seeking_state = AntStateSeeking(self)
        delivering_state = AntStateDelivering(self)
        hunting_state = AntStateHunting(self)
        self.brain.add_state(exploring_state)
        self.brain.add_state(seeking_state)
        self.brain.add_state(delivering_state)
        self.brain.add_state(hunting_state)
        self.carry_image = None
 
    def carry(self, image):
        self.carry_image = image
 
    def drop(self, surface):
        if self.carry_image:
            x, y = self.location
            w, h = self.carry_image.get_size()
            surface.blit(self.carry_image, (x-w, y-h/2))
            self.carry_image = None
 
    def render(self, surface):
        GameEntity.render(self, surface)
        if self.carry_image:
            x, y = self.location
            w, h = self.carry_image.get_size()
            surface.blit(self.carry_image, (x-w, y-h/2))
 
class AntStateExploring(State):
    def __init__(self, ant):
        State.__init__(self, "exploring")
        self.ant = ant
 
    def random_destination(self):
        w, h = SCREEN_SIZE
        self.ant.destination = Vector2(randint(0, w), randint(0, h))    
 
    def do_actions(self):
        if randint(1, 20) == 1:
            self.random_destination()
 
    def check_conditions(self):
        leaf = self.ant.world.get_close_entity("leaf", self.ant.location)
        if leaf is not None:
            self.ant.leaf_id = leaf.id
            return "seeking"
        spider = self.ant.world.get_close_entity("spider", NEST_POSITION, NEST_SIZE)
        if spider is not None:
            if self.ant.location.get_distance_to(spider.location) < 100.:
                self.ant.spider_id = spider.id
                return "hunting"
        return None
 
    def entry_actions(self):
        self.ant.speed = 120. + randint(-30, 30)
        self.random_destination()
 
class AntStateSeeking(State):
    def __init__(self, ant):
        State.__init__(self, "seeking")
        self.ant = ant
        self.leaf_id = None
 
    def check_conditions(self):
        leaf = self.ant.world.get(self.ant.leaf_id)
        if leaf is None:
            return "exploring"
        if self.ant.location.get_distance_to(leaf.location) < 5.0:
            self.ant.carry(leaf.image)
            self.ant.world.remove_entity(leaf)
            return "delivering"
        return None
 
    def entry_actions(self):
        leaf = self.ant.world.get(self.ant.leaf_id)
        if leaf is not None:
            self.ant.destination = leaf.location
            self.ant.speed = 160. + randint(-20, 20)
 
class AntStateDelivering(State):
    def __init__(self, ant):
        State.__init__(self, "delivering")
        self.ant = ant
 
    def check_conditions(self):
        if Vector2(*NEST_POSITION).get_distance_to(self.ant.location) < NEST_SIZE:
            if (randint(1, 10) == 1):
                self.ant.drop(self.ant.world.background)
                return "exploring"
        return None
 
    def entry_actions(self):
        self.ant.speed = 60.
        random_offset = Vector2(randint(-20, 20), randint(-20, 20))
        self.ant.destination = Vector2(*NEST_POSITION) + random_offset       
 
class AntStateHunting(State):
    def __init__(self, ant):
        State.__init__(self, "hunting")
        self.ant = ant
        self.got_kill = False
 
    def do_actions(self):
        spider = self.ant.world.get(self.ant.spider_id)
        if spider is None:
            return
        self.ant.destination = spider.location
        if self.ant.location.get_distance_to(spider.location) < 15.:
            if randint(1, 5) == 1:
                spider.bitten()
                if spider.health <= 0:
                    self.ant.carry(spider.image)
                    self.ant.world.remove_entity(spider)
                    self.got_kill = True
 
    def check_conditions(self):
        if self.got_kill:
            return "delivering"
        spider = self.ant.world.get(self.ant.spider_id)
        if spider is None:
            return "exploring"
        if spider.location.get_distance_to(NEST_POSITION) > NEST_SIZE * 3:
            return "exploring"
        return None
 
    def entry_actions(self):
        self.speed = 160. + randint(0, 50)
 
    def exit_actions(self):
        self.got_kill = False
 
def run():
    pygame.init()
    screen = pygame.display.set_mode(SCREEN_SIZE, 0, 32)
    world = World()
    w, h = SCREEN_SIZE
    clock = pygame.time.Clock()
    ant_image = pygame.image.load("ant.png").convert_alpha()
    leaf_image = pygame.image.load("leaf.png").convert_alpha()
    spider_image = pygame.image.load("spider.png").convert_alpha()
 
    for ant_no in xrange(ANT_COUNT):
        ant = Ant(world, ant_image)
        ant.location = Vector2(randint(0, w), randint(0, h))
        ant.brain.set_state("exploring")
        world.add_entity(ant)
 
    while True:
        for event in pygame.event.get():
            if event.type == QUIT:
                return
        time_passed = clock.tick(30)
 
        if randint(1, 10) == 1:
            leaf = Leaf(world, leaf_image)
            leaf.location = Vector2(randint(0, w), randint(0, h))
            world.add_entity(leaf)
 
        if randint(1, 100) == 1:
            spider = Spider(world, spider_image)
            spider.location = Vector2(-50, randint(0, h))
            spider.destination = Vector2(w+50, randint(0, h))
            world.add_entity(spider)
 
        world.process(time_passed)
        world.render(screen)
 
        pygame.display.update()
 
if __name__ == "__main__":
    run()