玩玩 3B1B 做视频的时候用的 manim

标签

开发/语言/Python

视频创作者/3Brown1Blue

视频创作者/3Brown1Blue/3B1B

开发/语言/Python/manim

操作系统/macOS

字数

1735 字

阅读时间

9 分钟

Note, there are two versions of manim. This repository began as a personal project by the author of 3Blue1Brown for the purpose of animating those videos, with video-specific code available here. In 2020 a group of developers forked it into what is now the community edition, with a goal of being more stable, better tested, quicker to respond to community contributions, and all around friendlier to get started with. See this page for more details.

正如 3b1b/manim 所说，manim 有两个版本，一个是 3Brown1Blue 最早做视频的时候作为个人项目用的 3b1b/manim，一个是后来 2020 年有一群好心的开发者 fork 了原先的 3b1b/manim 然后说希望做一个社区版本 ManimCommunity/manim，更新更快，社区支持更好。

考虑到开源社区的规模效应，接下来都会采用 ManimCommunity/manim 作为讲解，如果你需要用 3B1B 的 3b1b/manim 版本，请根据他们的文档来进行配置哦！

配置一下环境吧

跟随 Installation - Manim Community v0.18.0 文档来配置 macOS 的环境和依赖。

brew install py3cairo ffmpeg

我使用的是搭载了 Apple Silicon 芯片 M1 的 Macbook Pro，按照文档的说明，这里需要安装一些额外的依赖：

brew install pango pkg-config scipy

创建项目和依赖

Anaconda 真的有一点点反人类，既然我们是要做演示用的动画，还是应避免则避免使用 Anaconda 这么庞大和繁重的组件好了。

从这里开始，我使用 Poetry 来创建项目、管理虚拟环境，以及添加和管理依赖：

poetry new manim-test

❯ poetry new manim-test
Created package manim_test in manim-test

安装 manim 吧：

poetry add manim

如果你遇到了类似这样的错误：

❯ poetry add manim
Using version ^0.18.0 for manim

Updating dependencies
Resolving dependencies... (0.0s)

The current project's Python requirement (>=3.11,<4.0) is not compatible with some of the required packages Python requirement:
  - manim requires Python >=3.8,<3.13, so it will not be satisfied for Python >=3.13,<4.0

Because no versions of manim match >0.18.0,<0.19.0
 and manim (0.18.0) requires Python >=3.8,<3.13, manim is forbidden.
So, because manim-test depends on manim (^0.18.0), version solving failed.

  • Check your dependencies Python requirement: The Python requirement can be specified via the `python` or `markers` properties

    For manim, a possible solution would be to set the `python` property to ">=3.11,<3.13"

    https://python-poetry.org/docs/dependency-specification/#python-restricted-dependencies,
    https://python-poetry.org/docs/dependency-specification/#using-environment-markers

不用惊慌，我们按照下面的修改来更新一下 pyproject.toml 就好了：

[tool.poetry]
name = "manim-test"
version = "0.1.0"
description = ""
authors = ["Neko Ayaka <[email protected]>"]
readme = "README.md"
packages = [{include = "manim_test"}]

[tool.poetry.dependencies]
python = "^3.11"
python = ">=3.11,<3.13"

[build-system]
requires = ["poetry-core"]
build-backend = "poetry.core.masonry.api"

编写第一个 Scene 文件

可以清理一下不要的空文件，变成下面这样：

❯ tree
.
├── README.md
├── poetry.lock
└── pyproject.toml

然后我们创建一个新的目录

project/

在里面创建一个 scene.py 文件：

from manim import Scene, Circle, Create, PINK

class CreateCircle(Scene):
	def construct(self):
	circle = Circle()
	circle.set_fill(PINK, opacity=0.5)
	self.play(Create(circle))

这就是第一个 Scene 了。

接下来运行下面的命令就可以获得一个 MP4 文件：

poetry run manim -pql project/scene.py CreateCircle

对于这个命令，

• poetry run 代表了将会使用包管理器 poetry 并创建一个内联的 Python 环境来执行 Python
• manim 就是 manim 的 CLI 程序
• -pql 是 2 个命令行的合集，它们是：
  • -p 代表了 --preview，将会在渲染完成后预览
  • -q 代表了 --quality
  • 紧随其后的 l 代表了这是 -q 也就是 --quality 的一个选项，代表了低质量的渲染，将会输出到 480P 15 帧

就像是这样：

❯ poetry run manim -pql project/scene.py CreateCircle
Manim Community v0.18.0

[12/05/23 18:13:24] INFO     Animation 0 : Partial movie file written in                                                                                      scene_file_writer.py:527
                             '~/manim-test/media/videos/scene/480p15/partial_movie_files/CreateCircle/1185818338_1912650126_22313245
                             7.mp4'
                    INFO     Combining to Movie file.                                                                                                         scene_file_writer.py:617
                    INFO                                                                                                                                      scene_file_writer.py:735
                             File ready at '~/manim-test/media/videos/scene/480p15/CreateCircle.mp4'

                    INFO     Rendered CreateCircle                                                                                                                        scene.py:241
                             Played 1 animations
                    INFO     Previewed File at: '~/manim-test/media/videos/scene/480p15/CreateCircle.mp4'

这个视频会被放在

media/videos/scene/480p15/CreateCircle.mp4

目录下面，现在的目录结构也会发生变化：

❯ tree
.
├── README.md
├── media
│   ├── images
│   │   └── scene
│   └── videos
│       └── scene
│           └── 480p15
│               ├── CreateCircle.mp4
│               └── partial_movie_files
│                   └── CreateCircle
│                       ├── 1185818338_1912650126_223132457.mp4
│                       └── partial_movie_file_list.txt
├── poetry.lock
├── project
│   ├── __pycache__
│   │   └── scene.cpython-311.pyc
│   └── scene.py
└── pyproject.toml

它看起来是这样的：

渲染更高级的

刚才我们渲染出来的结果只有 480P 15 帧，所以预览的时候才感觉如此卡顿，这是正常的，这不怪你，也不怪 manim，这是因为在上面的例子中，我们使用的是这样的命令：

poetry run manim -pql project/scene.py CreateCircle

对于这个命令，

而 -pql 是 2 个命令行的合集，它们是：

• -p 代表了 --preview，将会在渲染完成后预览
• -q 代表了 --quality
• 紧随其后的 l 代表了这是 -q 也就是 --quality 的一个选项，代表了低质量的渲染，将会输出到 480P 15 帧

所以根据文档的说明，当我们在直接执行

manim -pql

的时候，实际上会自动回退到 manim render 的子命令调用上，这个时候我们可以通过执行

poetry run manim render --help

来观察 -q 都有哪些选项可以使用：

❯ poetry run manim render --help
Manim Community v0.18.0

Usage: manim render [OPTIONS] FILE [SCENE_NAMES]...

  Render SCENE(S) from the input FILE.

  FILE is the file path of the script or a config file.

  SCENES is an optional list of scenes in the file.

Global options:
  # ...

Render Options:
  -n, --from_animation_number TEXT
                                 Start rendering from n_0 until n_1. If n_1 is
                                 left unspecified, renders all scenes after n_0.
  -a, --write_all                Render all scenes in the input file.
  --format [png|gif|mp4|webm|mov]
  -s, --save_last_frame
  -q, --quality [l|m|h|p|k]      Render quality at the follow resolution
                                 framerates, respectively: 854x480 15FPS,
                                 1280x720 30FPS, 1920x1080 60FPS, 2560x1440
                                 60FPS, 3840x2160 60FPS
  -r, --resolution TEXT          Resolution in "W,H" for when 16:9 aspect ratio
                                 isn\'t possible.

  # ...

Ease of access options:
  --progress_bar [display|leave|none]
                                 Display progress bars and/or keep them
                                 displayed.
  -p, --preview                  Preview the Scene\'s animation. OpenGL does a
                                 live preview in a popup window. Cairo opens the
                                 rendered video file in the system default media
                                 player.
  -f, --show_in_file_browser     Show the output file in the file browser.
  --jupyter                      Using jupyter notebook magic.

Other options:
  --help                         Show this message and exit.

Made with <3 by Manim Community developers.

可以看到 -q 或者 --quality 有 5 个选项 l，m，h，p，k，分别是

	分辨率	帧率
l	854 x 480	15
m	1280 x 720	30
h	1920 x 1080	60
p	2560 x 1440	60
k	3840 x 2160	60

这个时候如果需要 4K 60 帧的渲染的话，就可以直接用

poetry run manim -pqk project/scene.py CreateCircle

来进行渲染，就像这样：

❯ poetry run manim -pqk project/scene.py CreateCircle
Manim Community v0.18.0

[12/05/23 18:54:04] INFO     Animation 0 : Partial movie file written in                                                                                      scene_file_writer.py:527
                             '~/manim-test/media/videos/scene/2160p60/partial_movie_files/CreateCircle/1457378895_1912650126_2231324
                             57.mp4'
                    INFO     Combining to Movie file.                                                                                                         scene_file_writer.py:617
                    INFO                                                                                                                                      scene_file_writer.py:735
                             File ready at '~/manim-test/media/videos/scene/2160p60/CreateCircle.mp4'

                    INFO     Rendered CreateCircle                                                                                                                        scene.py:241
                             Played 1 animations
                    INFO     Previewed File at: '~/manim-test/media/videos/scene/2160p60/CreateCircle.mp4'

，这个时候目录就会变成这样：

❯ tree
.
├── README.md
├── media
│   ├── images
│   │   └── scene
│   └── videos
│       └── scene
│           ├── 2160p60
│           │   ├── CreateCircle.mp4
│           │   └── partial_movie_files
│           │       └── CreateCircle
│           │           ├── 1457378895_1912650126_223132457.mp4
│           │           └── partial_movie_file_list.txt
│           └── 480p15
│               ├── CreateCircle.mp4
│               └── partial_movie_files
│                   └── CreateCircle
│                       ├── 1185818338_1912650126_223132457.mp4
│                       └── partial_movie_file_list.txt
├── poetry.lock
├── project
│   ├── __pycache__
│   │   └── scene.cpython-311.pyc
│   └── scene.py
└── pyproject.toml

锵锵，这样就可以了！清晰且丝滑。

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