python 3d 动画 python动画引擎

Python视频制作引擎Manim安装教程2021版

• 0 写在前面
• 1 效果展示
• 2 安装教程(Windows)

• 2.1 安装ffmpeg
• 2.2 安装Latex
• 2.3 安装dvisvgm
• 2.4 安装Manim

• 3 测试与开发

0 写在前面

相信很多同学就算没听过3Blue1Brown，也一定曾看过他们出品的视频，其从独特的视觉角度解说各种数学概念，内容包括线性代数、微积分、神经网络、傅里叶变换以及四元数等晦涩难懂的知识点。例如最火的《线性代数本质》系列视频。

那么这些视频是如何制作的呢？

这里需要引入的是Python的Manim视频支持引擎——专门用于支持数学可视化的媒体引擎，通过Manim并结合Python编程就可以实现3Blue1Brown的视频效果。本文给出Manim最新发行版的安装教程，因为网上的教程基本都过时了，容易踩坑。

1 效果展示

动画1：

动画2：(动图始终超过大小，放不上来)

2 安装教程(Windows)

2.1 安装ffmpeg

进入ffmpeg官网，点击如图所示的按钮

接着下载安装包

下载完后直接解压，并设置环境变量

2.2 安装Latex

进入官网MikTex官网，下载对应操作系统的安装包。

解压后运行安装程序.exe即可(环境变量会自动配置)

2.3 安装dvisvgm

进入官网dvisvgm下载相应操作系统的安装包，解压后运行安装程序即可。

2.4 安装Manim

通过git bash运行下面命令

git clone https://github.com/3b1b/manim.git
cd manim
# 安装python依赖
pip install -e .
python -m pip install -r requirements.txt

2021版重点：错误复现如下

LaTeX Error!  Not a worry, it happens to the best of us.

Traceback (most recent call last):
  File "D:\Program Files\Python3\Scripts\manimgl-script.py", line 33, in <module>
    sys.exit(load_entry_point('manimgl', 'console_scripts', 'manimgl')())
  File "d:\public\manim\manimlib\__main__.py", line 17, in main
    scene.run()
  File "d:\public\manim\manimlib\scene\scene.py", line 75, in run
    self.construct()
  File "example_scenes.py", line 29, in construct
    IntegerMatrix(matrix, include_background_rectangle=True),
  File "d:\public\manim\manimlib\mobject\matrix.py", line 81, in __init__
    self.add_brackets()
  File "d:\public\manim\manimlib\mobject\matrix.py", line 111, in add_brackets
    bracket_pair = Tex("".join([
  File "d:\public\manim\manimlib\mobject\svg\tex_mobject.py", line 167, in __init__
    super().__init__(full_string, **kwargs)
  File "d:\public\manim\manimlib\mobject\svg\tex_mobject.py", line 42, in __init__
    filename = tex_to_svg_file(full_tex)
  File "d:\public\manim\manimlib\utils\tex_file_writing.py", line 54, in tex_to_svg_file
    tex_to_svg(tex_file_content, svg_file)
  File "d:\public\manim\manimlib\utils\tex_file_writing.py", line 62, in tex_to_svg
    svg_file = dvi_to_svg(tex_to_dvi(tex_file))
  File "d:\public\manim\manimlib\utils\tex_file_writing.py", line 97, in tex_to_dvi
    with open(log_file, "r") as file:
FileNotFoundError: [Errno 2] No such file or directory: 'C:\\Users\\ADMINI~1\\AppData\\Local\\Temp\\Tex\\cf5d7f9f2e57398a.log'

该问题的最终解决方案是配置manim/manimlib/default_config.yml的缓存路径，其中"D:\\AIProject\\test\\manim\\tex"是manim目录下新建的一个空文件夹，用来存放tex输出文件。

3 测试与开发

进入manim目录下运行：

manimgl example_scenes.py OpeningManimExample

即可得到动画2的效果。

新建main.py文件，运行下面代码

from manimlib import *
class GraphExample(Scene):
    def construct(self):
        axes = Axes((-3, 10), (-1, 8))
        axes.add_coordinate_labels()

        self.play(Write(axes, lag_ratio=0.01, run_time=1))

        # Axes.get_graph will return the graph of a function
        sin_graph = axes.get_graph(
            lambda x: 2 * math.sin(x),
            color=BLUE,
        )
        # By default, it draws it so as to somewhat smoothly interpolate
        # between sampled points (x, f(x)).  If the graph is meant to have
        # a corner, though, you can set use_smoothing to False
        relu_graph = axes.get_graph(
            lambda x: max(x, 0),
            use_smoothing=False,
            color=YELLOW,
        )
        # For discontinuous functions, you can specify the point of
        # discontinuity so that it does not try to draw over the gap.
        step_graph = axes.get_graph(
            lambda x: 2.0 if x > 3 else 1.0,
            discontinuities=[3],
            color=GREEN,
        )

        # Axes.get_graph_label takes in either a string or a mobject.
        # If it's a string, it treats it as a LaTeX expression.  By default
        # it places the label next to the graph near the right side, and
        # has it match the color of the graph
        sin_label = axes.get_graph_label(sin_graph, "\\sin(x)")
        relu_label = axes.get_graph_label(relu_graph, Text("ReLU"))
        step_label = axes.get_graph_label(step_graph, Text("Step"), x=4)

        self.play(
            ShowCreation(sin_graph),
            FadeIn(sin_label, RIGHT),
        )
        self.wait(2)
        self.play(
            ReplacementTransform(sin_graph, relu_graph),
            FadeTransform(sin_label, relu_label),
        )
        self.wait()
        self.play(
            ReplacementTransform(relu_graph, step_graph),
            FadeTransform(relu_label, step_label),
        )
        self.wait()

        parabola = axes.get_graph(lambda x: 0.25 * x**2)
        parabola.set_stroke(BLUE)
        self.play(
            FadeOut(step_graph),
            FadeOut(step_label),
            ShowCreation(parabola)
        )
        self.wait()

        # You can use axes.input_to_graph_point, abbreviated
        # to axes.i2gp, to find a particular point on a graph
        dot = Dot(color=RED)
        dot.move_to(axes.i2gp(2, parabola))
        self.play(FadeIn(dot, scale=0.5))

        # A value tracker lets us animate a parameter, usually
        # with the intent of having other mobjects update based
        # on the parameter
        x_tracker = ValueTracker(2)
        f_always(
            dot.move_to,
            lambda: axes.i2gp(x_tracker.get_value(), parabola)
        )

        self.play(x_tracker.animate.set_value(4), run_time=3)
        self.play(x_tracker.animate.set_value(-2), run_time=3)
        self.wait()

即可得到动画1的效果。

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