用Python实现光线追踪效果：逼真的光影动画

屿小夏

发布于 2024-09-25 08:36:00

1040

发布于 2024-09-25 08:36:00

文章被收录于专栏：IT杂谈学习

引言

光线追踪是一种生成高质量图像的技术，通过模拟光线与物体之间的交互来生成逼真的光影效果。在这篇博客中，我们将使用Python来实现一个简单的光线追踪算法，生成一个具有光影效果的三维场景。本文将带你一步步实现这一效果，并展示如何使用Python编程实现光线追踪。

准备工作

前置条件

在开始之前，你需要确保你的系统已经安装了以下库：

Numpy：用于高效的数值计算
Pillow：用于图像处理

如果你还没有安装这些库，可以使用以下命令进行安装：

pip install numpy pillow

代码实现与解析

导入必要的库

我们首先需要导入Numpy和Pillow库：

import numpy as np
from PIL import Image

定义光线追踪函数

我们定义一个函数来处理光线追踪的主要逻辑：

def normalize(v):
    norm = np.linalg.norm(v)
    if norm == 0:
       return v
    return v / norm

def intersect_sphere(origin, direction, sphere):
    oc = origin - sphere['center']
    a = np.dot(direction, direction)
    b = 2.0 * np.dot(oc, direction)
    c = np.dot(oc, oc) - sphere['radius']**2
    discriminant = b**2 - 4*a*c
    if discriminant < 0:
        return False, None
    else:
        t = (-b - np.sqrt(discriminant)) / (2.0 * a)
        return True, t

def ray_trace(origin, direction, spheres):
    closest_t = float('inf')
    hit_sphere = None
    for sphere in spheres:
        hit, t = intersect_sphere(origin, direction, sphere)
        if hit and t < closest_t:
            closest_t = t
            hit_sphere = sphere
    if hit_sphere is None:
        return np.array([0, 0, 0])
    hit_point = origin + closest_t * direction
    normal = normalize(hit_point - hit_sphere['center'])
    light_dir = normalize(np.array([1, 1, -1]))
    intensity = max(np.dot(normal, light_dir), 0)
    color = intensity * hit_sphere['color']
    return color

设置场景和渲染图像

我们定义场景中的球体及其属性，然后进行光线追踪并渲染图像：

width, height = 800, 600
camera = np.array([0, 0, 1])
viewport = np.array([2, 1.5, 1])
image = Image.new("RGB", (width, height))
pixels = image.load()

spheres = [
    {'center': np.array([0, 0, -5]), 'radius': 1, 'color': np.array([255, 0, 0])},
    {'center': np.array([-2, 1, -6]), 'radius': 1, 'color': np.array([0, 255, 0])},
    {'center': np.array([2, 1, -6]), 'radius': 1, 'color': np.array([0, 0, 255])}
]

for y in range(height):
    for x in range(width):
        px = (x / width) * viewport[0] - viewport[0] / 2
        py = -(y / height) * viewport[1] + viewport[1] / 2
        direction = normalize(np.array([px, py, -viewport[2]]) - camera)
        color = ray_trace(camera, direction, spheres)
        pixels[x, y] = tuple(color.astype(int))

image.show()

完整代码

import numpy as np
from PIL import Image

def normalize(v):
    norm = np.linalg.norm(v)
    if norm == 0:
       return v
    return v / norm

def intersect_sphere(origin, direction, sphere):
    oc = origin - sphere['center']
    a = np.dot(direction, direction)
    b = 2.0 * np.dot(oc, direction)
    c = np.dot(oc, oc) - sphere['radius']**2
    discriminant = b**2 - 4*a*c
    if discriminant < 0:
        return False, None
    else:
        t = (-b - np.sqrt(discriminant)) / (2.0 * a)
        return True, t

def ray_trace(origin, direction, spheres):
    closest_t = float('inf')
    hit_sphere = None
    for sphere in spheres:
        hit, t = intersect_sphere(origin, direction, sphere)
        if hit and t < closest_t:
            closest_t = t
            hit_sphere = sphere
    if hit_sphere is None:
        return np.array([0, 0, 0])
    hit_point = origin + closest_t * direction
    normal = normalize(hit_point - hit_sphere['center'])
    light_dir = normalize(np.array([1, 1, -1]))
    intensity = max(np.dot(normal, light_dir), 0)
    color = intensity * hit_sphere['color']
    return color

width, height = 800, 600
camera = np.array([0, 0, 1])
viewport = np.array([2, 1.5, 1])
image = Image.new("RGB", (width, height))
pixels = image.load()

spheres = [
    {'center': np.array([0, 0, -5]), 'radius': 1, 'color': np.array([255, 0, 0])},
    {'center': np.array([-2, 1, -6]), 'radius': 1, 'color': np.array([0, 255, 0])},
    {'center': np.array([2, 1, -6]), 'radius': 1, 'color': np.array([0, 0, 255])}
]

for y in range(height):
    for x in range(width):
        px = (x / width) * viewport[0] - viewport[0] / 2
        py = -(y / height) * viewport[1] + viewport[1] / 2
        direction = normalize(np.array([px, py, -viewport[2]]) - camera)
        color = ray_trace(camera, direction, spheres)
        pixels[x, y] = tuple(color.astype(int))

image.show()

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原始发表：2024-09-23，如有侵权请联系 cloudcommunity@tencent.com 删除

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