Manim文档及源码笔记-CE教程BE03英文笔记速览版

Manim文档及源码笔记-CE教程BE03英文笔记速览版

Animation Deep Dive _ Mathematical Animations WITH EASE

前言

这次筛选到了Behackl博士的教程，逐步拆解，更为细腻~
参考视频在此【或请自行搜索上面的英文标题】；
本页中文版传送门【建设中】；

更新【new】：

• 8月23日
• • 文首标注了“前言”与“正文”；
• • 本系列暂告段落，升级了系列目录，放到了文尾；
• 后续更新备忘：文中“【建设中】”的内容；欢迎朋友们催更~

首先，国际通则：Just GET STARTED~ JUST DO IT~

然后，让我们行动起来~
注：
1、代码实践过程根据运行环境及笔记需要略有改动；
2、经过实践理解，加入了一些自己的注释；
3、常见问题及大概率解决方案：

• Python相关：注意缩进、冒号，中英文字符、大小写；
• Manim相关：安装与运行环境；
• Coding相关：检查拼写；

正文

Animation Keyword Arguments

• moject- every animation is tied to a mobject
• run_time- the animaion’s play duration
• rate_func- a function r: [0, 1] →[0,1] controlling animation progression
• and some more technical, less relevant ones

%%manim -v WARNING -qm BasicAnimations
from manim import *
from colour import Color

class BasicAnimations(Scene):
    def construct(self):
        polys=VGroup(
            *[RegularPolygon(5,radius=1,fill_opacity=0.5,
            color=Color(hue=j/5,saturation=1,luminance=0.5))for j in range(5)]
        ).arrange(RIGHT)
        self.play(DrawBorderThenFill(polys),run_time=2)
        self.play(
            Rotate(polys[0],PI,rate_func=lambda t:t), # rate_func=linear
            Rotate(polys[1],PI,rate_func=smooth), # default behavior
            Rotate(polys[2],PI,rate_func=lambda t:np.sin(t*PI)), # 
            Rotate(polys[3],PI,rate_func=there_and_back), # 
            Rotate(polys[4],PI,rate_func=lambda t:1-abs(1-2*t)), # 
            run_time=2
        )
        self.wait()

BasicAnimations

看一下控制因子的图像，顺便练习一下第一章的作图：
Manim文档及源码笔记-CE教程BE01英文笔记速览版

%%manim -v WARNING -qm polys

class polys(Scene):
    def construct(self):
        ax=Axes(x_range=(-10,10),y_range=(-10,10))
        curve0=ax.plot(lambda t: t, color=RED)
        curve2=ax.plot(lambda t: np.sin(t*PI), color=GREEN)
        curve4=ax.plot(lambda t: 1-abs(1-2*t), color=PURPLE)
        self.add(ax, curve0,curve2,curve4)

Basic Mechanisms of Scene.play

• Multiple animations can be passed as positional arguments:
  self.play(anim1, anim2, …)
• Passing animation keyword arguments propagates them to all animations:
  self.play(anim1, anim2, run_time=3)
• Manim will not error if you try to pass conflicting animations, it cannot combine different animations for you!
  self.play(Rotate( s, PI), Rotate( s, -PI))

%%manim -v WARNING -qm ConflictingAnimations

class ConflictingAnimations(Scene):
    def construct(self):
        s=Square()
        self.add(s)
        self.play(Rotate(s,PI),Rotate(s,-PI),run_time=3)
        

ConflictingAnimations

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Overlapping Animations

• Useful for grouping animations: AnimationGroup
• Like Group or VGroup, but for animations
• Keyword argument lag_ratio, number between 0 and 1,
• controls whether animations are played simultaneously (0), successively (1), or anything in between
• Finer control possible by editing list in anims_with_timings attribute

%%manim -v WARNING -qm LaggingGroup

class LaggingGroup(Scene):
    def construct(self):
        squares=VGroup(*[Square(color=Color(hue=j/20,saturation=1,luminance=0.5),
        fill_opacity=0.5) for j in range(20)]).arrange_in_grid(4,5).scale(0.75)
        self.play(AnimationGroup(*[FadeIn(s) for s in squares],lag_ratio=1))

LaggingGroup

Part 2 Animations from Method calls and Functions

The .animate syntax

• Problem: mobj.method() usually returns a mobject, mobjects cannot be passed to play
• Solution: Mobjects have a .animate property which can bulid animations!

def construct(self):
    s=Square()
    self.play(s.animate.shift(RIGHT)) # animation of shift by RIGHT
    self.play(s.animate(run_time=2).scale(3)) # supports animation keywords
    self.play(s.animate.scale(1/2).shift(2*LEFT)) # supports chaining

Note:
.animate is not aware of how your mobjects change knows only start& end and interpolates linearly between them!

%%manim -v WARNING -qm AnimateSyntax

class AnimateSyntax(Scene):
    def construct(self):
        s=Square(color=GREEN,fill_opacity=0.5)
        c=Circle(color=RED,fill_opacity=0.5)
        self.add(s,c)

        self.play(s.animate.shift(UP),c.animate.shift(DOWN))

AnimateSyntax

%%manim -v WARNING -qm AnimateSyntax1

class AnimateSyntax1(Scene):
    def construct(self):
        s=Square(color=GREEN,fill_opacity=0.5)
        c=Circle(color=RED,fill_opacity=0.5)
        self.add(s,c)

        self.play(s.animate.shift(UP),c.animate.shift(DOWN))
        self.play(VGroup(s,c).animate.arrange(RIGHT,buff=1))

AnimateSyntax1

%%manim -v WARNING -qm AnimateSyntax2

class AnimateSyntax2(Scene):
    def construct(self):
        s=Square(color=GREEN,fill_opacity=0.5)
        c=Circle(color=RED,fill_opacity=0.5)
        self.add(s,c)

        self.play(s.animate.shift(UP),c.animate.shift(DOWN))
        self.play(VGroup(s,c).animate.arrange(RIGHT,buff=1))
        self.play(c.animate(rate_func=linear).shift(RIGHT).scale(2))

AnimateSyntax2

%%manim -v WARNING -qm AnimateProblem
class AnimateProblem(Scene):
    def construct(self):
        left_square=Square()
        right_square=Square()
        VGroup(left_square,right_square).arrange(RIGHT,buff=1)
        self.add(left_square,right_square)
        self.play(left_square.animate.rotate(PI),
                    Rotate(right_square,PI),run_time=2)
        self.wait()

AnimateProblem

Related animations: MoveToTarget and Restore

• General philosophy: create a copy of a mobject, modify it however you like, then transform between original mobject and modified copy
• MoveToTarget: call mob.generate_target(), then modify mob.target- animate with MoveToTarget(mob)
• Restore: call mob.save_state(), then keep modifying mob- animate return to saved state with Restore(mob)

%%manim -v WARNING -qm Animationchanisms
class Animationchanisms(Scene):
    def construct(self):
        c=Circle()

        c.generate_target()
        c.target.set_fill(color=GREEN,opacity=0.5)
        c.target.shift(2*RIGHT+UP).scale(0.5)

        self.add(c)
        self.wait()
        self.play(MoveToTarget(c))

Animationchanisms

%%manim -v WARNING -qm Animationchanisms1
class Animationchanisms1(Scene):
    def construct(self):
        c=Circle()

        c.generate_target()
        c.target.set_fill(color=GREEN,opacity=0.5)
        c.target.shift(2*RIGHT+UP).scale(0.5)

        self.add(c)
        self.wait()
        self.play(MoveToTarget(c))

        s=Square()
        s.save_state()
        self.play(FadeIn(s))
        self.play(s.animate.set_color(PURPLE).set_opacity(0.5).shift(2*LEFT).scale(3))
        self.play(s.animate.shift(5*DOWN).rotate(PI/4))
        self.wait()
        self.play(Restore(s),run_time=2)
        self.wait()
        

Animationchanisms1

Custom Animations via Functions

• Abstraction: an animation is a function mapping( mobject, completion ratio) to a mobject

def move_somewhere(mobj,alpha):
    mobj.move_to(alpha*RIGHT+alpha**2*2*UP)

• Given such a function, UpdateFromAlphaFunc constructs the corresponding animation!
• Tip: store initial state in custom mobject attribute to allow for more flexibility!
  mobj.initial_position=mobj.get_center() … then mobj.initial_position is available in the animation function- or write custom animation

%%manim -v WARNING -qm SimpleCustomAnimation
from colour import Color
class SimpleCustomAnimation(Scene):
    def construct(self):
        def spiral_out(mobject,t):
            radius=4*t
            angle=2*5*2*PI
            mobject.move_to(radius*(np.cos(angle)*RIGHT+np.sin(angle)*UP))
            mobject.set_color(Color(hue=t,saturation=1,luminance=0.5))
            mobject.set_opacity(1-t)
            
        d=Dot(color=WHITE)
        self.add(d)
        self.play(UpdateFromAlphaFunc(d,spiral_out,run_time=3))

SimpleCustomAnimation

Part 3 Anatomy of Animations

Animation methods called in a lifecycle

• begin() - prepares first animation frame; stores mobject copy in self.starting_mobject
• interpolate_mobject(alpha) - brings self.mobject to the state of $\alpha$% of animation completed; default: delegates to submobjects
• interpolate_submobject(sub, sub_start, alpha) - same as above, but for a specific submobjedt( in argument)
• finish() - finishes animation, produces last frame
• clean_up_from_scend(scene)- all remaining mobject and scene cleanup( e.g., removing mobjects)

Implementing your own Animatin class

• Basically: inherit from Animation, override
  interpolate_mobject or interpolate_submobject
• Compare how other Animations in the library are
• Good luck~

%%manim -v WARNING -qm CustomAnimationExample

from colour import Color
class Disperse(Animation):
    def __init__(self,mobject,dot_radius=0.05,dot_number=100, **kwargs):
        super().__init__(mobject,**kwargs)
        self.dot_radius=dot_radius
        self.dot_number=dot_number

    def begin(self):
        dots=VGroup(
            *[Dot(radius=self.dot_radius).move_to(self.mobject.point_from_proportion(p))
             for p in np.linspace(0,1,self.dot_number)]
             )
        for dot in dots:
            dot.initial_position=dot.get_center()
            dot.shift_vector=2*(dot.get_center()-self.mobject.get_center())
        dots.set_opacity(0)
        self.mobject.add(dots)
        self.dots=dots
        super().begin()
        
    def clean_up_from_scene(self,scene:"Scene") -> None:
        super().clean_up_from_scene(scene)
        scene.remove(self.dots)

    def interpolate_mobject(self,alpha):
        if alpha<=0.5:
            self.mobject.set_opacity(1-2*alpha,family=False)
            self.dots.set_opacity(2*alpha)
        else:
            self.mobject.set_opacity(0)
            self.dots.set_opacity(2*(1-alpha))
            for dot in self.dots:
                dot.move_to(dot.initial_position+2*(alpha-0.5)*dot.shift_vector)

class CustomAnimationExample(Scene):
    def construct(self):
        st=Star(color=YELLOW, fill_opacity=1).scale(3)
        self.add(st)
        self.wait()
        self.play(Disperse(st,dot_number=200,run_time=4))

CustomAnimationExample

本系列目录【new】

Manim文档及源码笔记-CE教程BE01英文笔记速览版
Manim文档及源码笔记-CE教程BE02英文笔记速览版
Manim文档及源码笔记-CE教程BE03英文笔记速览版【本文】
Manim文档及源码笔记-CE教程BE04英文笔记速览版
Manim文档及源码笔记-CE教程BE05英文笔记速览版