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import pygame
from pygame.locals import *
from queue import PriorityQueue
WIDTH = 800
HEIGHT = WIDTH
COLS = 50
ROWS = COLS
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 255, 0)
YELLOW = (255, 255, 0)
WHITE = (255, 255, 255)
BLACK = (0, 0, 0)
PURPLE = (128, 0, 128)
ORANGE = (255, 165, 0)
GREY = (128, 128, 128)
TURQUOISE = (64, 224, 208)
# spot
spot_width = WIDTH//COLS
spot_height = HEIGHT // ROWS
win = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption('grid world')
class Spot:
def __init__(self, r, c):
self.r = r
self.c = c
self.x = c * spot_width
self.y = r * spot_height
self.color = WHITE
self.is_start = False
self.is_barrier = False
self.is_end = False
def make_start(self):
self.color = ORANGE
self.is_start = True
def make_end(self):
self.color = TURQUOISE
self.is_end = True
def make_barrier(self):
self.color = BLACK
self.is_barrier = True
def make_open(self):
self.color = GREEN
def make_path(self):
self.color = PURPLE
def make_closed(self):
self.color = RED
def update_neighbors(self):
self.neighbors = []
if self.c > 0 and not grid_world[self.r][self.c - 1].is_barrier:
self.neighbors.append(grid_world[self.r][self.c - 1])
if self.c < COLS - 1 and not grid_world[self.r][self.c + 1].is_barrier:
self.neighbors.append(grid_world[self.r][self.c + 1])
if self.r > 0 and not grid_world[self.r-1][self.c].is_barrier:
self.neighbors.append(grid_world[self.r-1][self.c])
if self.r < ROWS - 1 and not grid_world[self.r+1][self.c].is_barrier:
self.neighbors.append(grid_world[self.r+1][self.c])
def draw(self, win):
pygame.draw.rect(win, self.color, (self.x, self.y, spot_width, spot_height))
def __lt__(self, other):
return False
grid_world = []
def make_grid_world():
for r in range(ROWS):
grid_world.append([])
for c in range(COLS):
grid_world[r].append(Spot(r, c))
def draw():
win.fill(WHITE)
for r in range(ROWS):
for c in range(COLS):
spot = grid_world[r][c]
spot.draw(win)
for i in range(ROWS):
pygame.draw.line(win, GREY, (0, i*spot_height), (WIDTH, i*spot_height))
for j in range(COLS):
pygame.draw.line(win, GREY, (j*spot_width, 0), (j * spot_width, HEIGHT))
pygame.display.update()
def map_pos_to_spot(pos):
x, y = pos
r, c = y//spot_height, x//spot_width
return r, c
# 曼哈顿距离
def h(spot1, spot2):
x1, y1 = spot1.c, spot1.r
x2, y2 = spot2.c, spot2.r
return abs(x1-x2) + abs(y1-y2)
def reconstruct_path(path_from, current):
while current in path_from:
current = path_from[current]
current.make_path()
draw()
def algo(start, end):
pq = PriorityQueue()
pq.put((float('inf'), start))
f_score = {spot: float('inf') for row in grid_world for spot in row}
g_score = {spot: float('inf') for row in grid_world for spot in row}
g_score[start] = 0
f_score[start] = h(start, end)
# f = g + h
# f(current) = g(current) + h(current)
# f(current) 经过 current 节点的预估路径
# g(current)：走到 current 需要经过的距离
# h(current)：预估的一个距离
path_from = {}
while not pq.empty():
current = pq.get()[1]
if current == end:
reconstruct_path(path_from, end)
end.make_end()
return True
for neighbor in current.neighbors:
tmp_g_score = g_score[current] + 1
if tmp_g_score < g_score[neighbor]:
neighbor.make_open()
path_from[neighbor] = current
g_score[neighbor] = tmp_g_score
f_score[neighbor] = tmp_g_score + h(neighbor, end)
pq.put((f_score[neighbor], neighbor))
draw()
if current != start:
current.make_closed()
return False
if __name__ == '__main__':
run = True
make_grid_world()
start = None
end = None
while run:
draw()
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
if event.type == KEYDOWN:
if event.key == K_ESCAPE:
run = False
left, center, right = pygame.mouse.get_pressed()
# if left:
# print('left')
# if center:
# print('center')
# if right: for r in range(ROWS):
# for c in range(COLS):
# spot = grid_world[r][c]
# spot.draw(win)
# print('right')
if left:
pos = pygame.mouse.get_pos()
r, c = map_pos_to_spot(pos)
spot = grid_world[r][c]
if not start:
start = spot
start.make_start()
elif not end:
end = spot
end.make_end()
else:
spot.make_barrier()
if event.type == KEYDOWN:
if event.key == K_SPACE and start and end:
for row in grid_world:
for spot in row:
spot.update_neighbors()
algo(start, end)
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