8. 贪吃蛇游戏制作¶
8.1. 基本原理¶
可交互的动画片
跟电影的原理类似，游戏中的动画效果，本质上是快速的在屏幕上绘制图像，一般在电脑上 每秒绘制 60 次，就能够达到非常连续高品质的动画效果。
程序基本流程
- 游戏循环的作用
- 保证游戏不会直接退出
- 变化图像位置 — 动画效果
- 每隔一段时间移动或更新一下所有图像的位置
- 检测用户交互 — 按键、鼠标等
- 游戏中的坐标系描述
- 原点在左上角 (0, 0)
- x 轴水平方向向右，逐渐增加
- y 轴垂直方向向下，逐渐增加
- 在游戏中，所有可见的元素都是以矩形区域来描述位置的
- 要描述一个矩形区域有四个要素：(x, y) (width, height)
- 贪吃蛇的网格坐标
- 将屏幕分成若干10*10的网格
- 对指定网格填充颜色形成蛇的身体
- 对指定网格填充颜色形成食物
- 网格左上角坐标和屏幕坐标的变换
- x = 网格横坐标 * 10 + a
- y = 网格纵坐标 * 10 + b
- 贪吃蛇的移动
- 移动方向填充身体颜色
- 蛇尾部填充背景颜色
- 不能向自己的反方向前进
8.2. 代码分析¶
- Grid网格类
class Grid(object):
def __init__(self, master=None, x=10, y=10, w=222, h=303):
self.x = x
self.y = y
self.w = w
self.h = h
self.width = w // 10 - 1
self.height = h // 10 - 1
self.bg = 0x000000
print(self.width, self.height)
# 画背景
for i in range(320):
screen.drawline(0, i, 239, i, 1, self.bg)
# 画边界
screen.drawline(x, y, x + w - 1, y, 1, 0xFFFFFF)
screen.drawline(x + w - 1, y, x + w - 1, y + h, 1, 0xFFFFFF)
screen.drawline(x, y + h, x + w - 1, y + h, 1, 0xFFFFFF)
screen.drawline(x, y, x, y + h, 1, 0xFFFFFF)
def draw(self, pos, color):
x = pos[0] * 10 + self.x + 1
y = pos[1] * 10 + self.y + 1
for i in range(10):
screen.drawline(x, y + i, x + 10 - 1, y + i, 1, color)
- 食物类
class Food(object):
def __init__(self, grid, color=0xFF0000):
self.grid = grid
self.color = color
self.set_pos()
self.type = 1
def set_pos(self):
x = randint(0, self.grid.width - 1)
y = randint(0, self.grid.height - 1)
self.pos = (x, y)
def display(self):
self.grid.draw(self.pos, self.color)
- 蛇类
class Snake(object):
def __init__(self, grid, color=0xFFFFFF):
self.grid = grid
self.color = color
self.body = [(5, 5), (5, 6), (5, 7)]
self.direction = "Up"
for i in self.body:
self.grid.draw(i, self.color)
# 这个方法用于游戏重新开始时初始化贪吃蛇的位置
def initial(self):
while not len(self.body) == 0:
pop = self.body.pop()
self.grid.draw(pop, self.grid.bg)
self.body = [(8, 11), (8, 12), (8, 13)]
self.direction = "Up"
self.color = 0xFFFFFF
for i in self.body:
self.grid.draw(i, self.color)
# 蛇像一个指定点移动
def move(self, new):
self.body.insert(0, new)
pop = self.body.pop()
self.grid.draw(pop, self.grid.bg)
self.grid.draw(new, self.color)
# 蛇像一个指定点移动，并增加长度
def add(self, new):
self.body.insert(0, new)
self.grid.draw(new, self.color)
# 蛇吃到了特殊食物1，剪短自身的长度
def cut_down(self, new):
self.body.insert(0, new)
self.grid.draw(new, self.color)
for i in range(0, 3):
pop = self.body.pop()
self.grid.draw(pop, self.grid.bg)
# 蛇吃到了特殊食物2，回到最初长度
def init(self, new):
self.body.insert(0, new)
self.grid.draw(new, self.color)
while len(self.body) > 3:
pop = self.body.pop()
self.grid.draw(pop, self.grid.bg)
# 蛇吃到了特殊食物3，改变了自身的颜色,纯属好玩
def change(self, new, color):
self.color = color
self.body.insert(0, new)
for item in self.body:
self.grid.draw(item, self.color)
- 游戏类
class SnakeGame():
def __init__(self):
screen.clear();
self.grid = Grid()
self.snake = Snake(self.grid)
self.food = Food(self.grid)
self.gameover = False
self.score = 0
self.status = ['run', 'stop']
self.speed = 300
self.display_food()
# type1:普通食物 type2:减少2 type3:大乐透，回到最初状态 type4:吃了会变色
def display_food(self):
self.food.color = 0xFF0000
self.food.type = 1
if randint(0, 40) == 5:
self.food.color = 0x00FF00
self.food.type = 3
while (self.food.pos in self.snake.body):
self.food.set_pos()
self.food.display()
elif randint(0, 4) == 2:
self.food.color = 0x0000FF
self.food.type = 4
while (self.food.pos in self.snake.body):
self.food.set_pos()
self.food.display()
elif len(self.snake.body) > 10 and randint(0, 16) == 5:
self.food.color = 0xFFFFFF
self.food.type = 2
while (self.food.pos in self.snake.body):
self.food.set_pos()
self.food.display()
else:
while (self.food.pos in self.snake.body):
self.food.set_pos()
self.food.display()
print(self.food.type)
# 这个方法用于游戏重新开始时初始化游戏
def initial(self):
self.gameover = False
self.score = 0
# self.m.set("Score:"+str(self.score))
self.snake.initial()
def run(self):
while True:
i = 0
j = -1
for k in keys:
if k.value() == 0:
if i != j:
print("i=", i)
print("j=", j)
j = i
self.key_release(i)
i = i + 1
if i > 3:
i = 0
# 首先判断游戏是否暂停
if not self.status[0] == 'stop':
if self.gameover == True:
self.initial()
else:
# 判断游戏是否结束
self.move()
time.sleep_ms(125)
# self.after(self.speed, self.run)
def move(self, color=0xFFFFFF):
# 计算蛇下一次移动的点
head = self.snake.body[0]
# print(self.snake.direction)
if self.snake.direction == 'Up':
if head[1] - 1 < 0:
new = (head[0], 29)
else:
new = (head[0], head[1] - 1)
elif self.snake.direction == 'Down':
new = (head[0], (head[1] + 1) % 29)
elif self.snake.direction == 'Left':
if head[0] - 1 < 0:
new = (21, head[1])
else:
new = (head[0] - 1, head[1])
else:
new = ((head[0] + 1) % 21, head[1])
# 撞到自己，设置游戏结束的标志位，等待下一循环
if new in self.snake.body:
self.gameover = True
# 吃到食物
elif new == self.food.pos:
print(self.food.type)
if self.food.type == 1:
self.snake.add(new)
elif self.food.type == 2:
self.snake.cut_down(new)
elif self.food.type == 4:
self.snake.change(new, 0x0000FF)
else:
self.snake.init(new)
self.display_food()
# 什么都没撞到，继续前进
else:
self.snake.move(new)
def key_release(self, key):
keymatch = ["Down", "Left", "Up", "Right"]
key_dict = {"Up": "Down", "Down": "Up", "Left": "Right", "Right": "Left"}
print(keymatch[key])
# 蛇不可以像自己的反方向走
if keymatch[key] in key_dict and not keymatch[key] == key_dict[self.snake.direction]:
self.snake.direction = keymatch[key]
self.move()