Python 贪吃蛇游戏数学

Question

我正在使用 python 3 并遵循[教程][1]。我遇到了问题，我的蛇没有动。它在 vec_add() 上调用无效语法，当我删除一些括号时，我得到：

Traceback (most recent call last):
  File "_ctypes/callbacks.c", line 234, in 'calling callback function'
  File "C:\Python34\lib\site-packages\OpenGL\GLUT\special.py", line 164, in deregister
    function( value )
  File "C:/Users/jay/Desktop/Python/OpenGL/Snake Game.py", line 51, in update
    snake.insert(0, vec_add(snake[0], snake_dir))      # insert new position in the beginning of the snake list
TypeError: vec_add() missing 2 required positional arguments: 'x2' and 'y2'

蛇应该向右移动。

from OpenGL.GL import *
from OpenGL.GLUT import *
from OpenGL.GLU import *

window = 0                                             # glut window number
width, height = 500, 500                               # window size
field_width, field_height = 50, 50                     # internal resolution
snake = [(20, 20)]                                       # snake list of (x, u) positions
snake_dir = (1, 0)                                     # snake movement direction
#Note: snake dir (1, 0) means that its current movement
#direction is x=1 and y=0, which means it moves to the right.
interval = 200 # update interval in milliseconds

def vec_add((x1, y1), (x2, y2)):    
    return (x1 + x2, y1 + y2)


def refresh2d_custom(width, height, internal_width, internal_height):
    glViewport(0, 0, width, height)
    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    glOrtho(0.0, internal_width, 0.0, internal_height, 0.0, 1.0)
    glMatrixMode (GL_MODELVIEW)
    glLoadIdentity()

def draw_rect(x, y, width, height):
    glBegin(GL_QUADS)                                  # start drawing a rectangle
    glVertex2f(x, y)                                   # bottom left point
    glVertex2f(x + width, y)                           # bottom right point
    glVertex2f(x + width, y + height)                  # top right point
    glVertex2f(x, y + height)                          # top left point
    glEnd()                                            # done drawing a rectangle

def draw_snake():
    glColor3f(1.0, 1.0, 1.0)  # set color to white
    for x, y in snake:        # go through each (x, y) entry
        draw_rect(x, y, 1, 1) # draw it at (x, y) with width=1 and height=1


def draw():                                            # draw is called all the time
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) # clear the screen
    glLoadIdentity()                                   # reset position
    refresh2d_custom(width, height, field_width, field_height)

    draw_snake()

    glutSwapBuffers()                                  # important for double buffering


def update(value):
    snake.insert(0, vec_add(snake[0], snake_dir))      # insert new position in the beginning of the snake list
    snake.pop()                                        # remove the last element

    glutTimerFunc(interval, update, 0)                 # trigger next update


# initialization
glutInit()                                             # initialize glut
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_ALPHA | GLUT_DEPTH)
glutInitWindowSize(width, height)                      # set window size
glutInitWindowPosition(0, 0)                           # set window position
window = glutCreateWindow(b"noobtuts.com")              # create window with title
glutDisplayFunc(draw)                                  # set draw function callback
glutIdleFunc(draw)                                     # draw all the time
glutTimerFunc(interval, update, 0)                     # trigger next update
glutMainLoop()                                         # start everything

Answer 1

在这个函数中：

def vec_add((x1, y1), (x2, y2)):    
    return (x1 + x2, y1 + y2)

Python 不支持函数参数列表中的解构。所以你可以这样写：

def vec_add(p1, p2):    
    return (p1[0] + p2[0], p1[1] + p2[1])

这与您对 vec_add 的现有调用兼容。

Answer 2

使用普通元组来存储和操作坐标很好，但您可能会发现命名元组是一种更方便的数据结构。命名元组的元素可以通过名称或索引访问，并且命名元组是 class 您可以向其添加自定义方法。

这是一个简短的演示，它向一个名为 tuple 的 2 元素添加了向量加法和减法方法，它还添加了一个有用的 __str__ 方法。通过定义 __add__ 和 __sub__ 我们可以简单地使用 + 和 - 运算符执行向量加法和减法，这比使用更容易键入（和阅读）显式函数调用。

#!/usr/bin/env python

from collections import namedtuple

Vector = namedtuple('Vector', ['x', 'y'])

Vector.__str__ = lambda self: 'Vector({s.x}, {s.y})'.format(s=self)
Vector.__add__ = lambda self, other: Vector(self.x + other.x, self.y + other.y)
Vector.__sub__ = lambda self, other: Vector(self.x - other.x, self.y - other.y)

snake = [Vector(20, 20)]
snake_dir = Vector(x=1, y=0)
print(snake_dir.x)
print(snake[0] + snake_dir)

输出

1
Vector(21, 20)

请参阅 Python 文档中的 namedtuple for further info; here's the Python 3 version 个文档。

您也可以从头开始定义自己的 Vector 或 Point class，如。如果你想存储很多点，你可能希望将 __slots__ = () 添加到你的 class 定义中以最小化内存使用，如 Python 2 命名元组文档中所述。

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