用Python写一个画球体的代码

下面是一个使用 Python 和 Pygame 库绘制球体的示例代码：

import pygame
from math import sin, cos, pi

# 初始化 Pygame
pygame.init()

# 定义球体参数
radius = 100
width = 640
height = 480
fov = pi / 2
distance = (width / 2) / tan(fov / 2)

# 创建窗口
screen = pygame.display.set_mode((width, height))

# 定义球体顶点数组
vertices = []
for i in range(20):
    phi = pi * i / 10
    for j in range(20):
        theta = 2 * pi * j / 20
        x = radius * sin(phi) * cos(theta)
        y = radius * sin(phi) * sin(theta)
        z = radius * cos(phi)
        vertices.append((x, y, z))

# 定义球体面数组
faces = []
for i in range(19):
    for j in range(20):
        a = i * 20 + j
        b = i * 20 + (j + 1) % 20
        c = (i + 1) * 20 + j
        d = (i + 1) * 20 + (j + 1) % 20
        faces.append((a, b, c))
        faces.append((b, d, c))

# 定义颜色
white = (255, 255, 255)

# 渲染循环
while True:
    # 处理事件
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            exit()

    # 清空屏幕
    screen.fill((0, 0, 0))

    # 渲染球体
    for face in faces:
        # 计算面的中心点
        x, y, z = 0, 0, 0
        for vertex in face:
            x += vertices[vertex][0]
            y += vertices[vertex][1]
            z += vertices[vertex][2]
        x /= 3
        y /= 3
        z /= 3

        # 计算面的法向量
        nx, ny, nz = 0, 0, 0
        for vertex in face:
            x1, y1, z1 = vertices[vertex]
            x2, y2, z2 = vertices[(vertex + 1) % len(vertices)]
            nx += (y1 - y2) * (z1 + z2)
            ny += (z1 - z2) * (x1 + x2)
            nz += (x1 - x2) * (y1 + y2)
        length = (nx * nx + ny * ny + nz * nz) ** 0.5
        nx /= length
        ny /= length
        nz /= length

        # 计算面的灰度值
        brightness = nx * 0.5 + ny * 0.5 + nz * 0.5

        # 计算面的投影坐标
        x1 = x * distance / (z + distance) + width / 2
        y1 = -y * distance / (z + distance) + height / 2

        # 绘制面
        if brightness > 0:
            pygame.draw.polygon(screen, (brightness * 255, brightness * 255, brightness * 255), [(x1 + vertices[vertex][0], y1 - vertices[vertex][1]) for vertex in face])

    # 更新屏幕
    pygame.display.flip()

这段代码使用了 Pygame 库绘制球体，首先定义了球体的顶点和面数组，然后在渲染循环中计算每个面的中心点、法向量、灰度值和投影坐标，最后根据灰度值绘制面。