Compass

Original author: jj-math (Bilibili creator Jiujin Math)

Source repository: GitHub

License: MIT (see the upstream repository for the full license text)

Compass provides compass-and-straightedge construction tools for Manim. It includes Compass, Ruler and Pencil mobjects plus matching animation classes. The code is bundled inside manim_extensions as the manim_extensions.compass subpackage and is also kept as a Git submodule under third_party/.

Features

• Compass mobject and compass animations: MoveNiddleTipTo, RotateCompass, SplitCompass, PutCompass, PutCompassAway, DrawArc.

• Pencil mobject and pencil animations: MovePencilTipTo, PutPencilAway, MovePencilAlongPath, DrawPath.

• Ruler mobject and ruler animations: PutRuler, PutRulerAway.

• CompassScene – a convenience Scene subclass pre-equipped with a compass, ruler, and pencil.

Quick start

Import directly from manim_extensions (from manim_extensions.compass import *).

Compass example

Example: CompassExample

from manim import *
from manim_extensions.compass import Compass, MoveNiddleTipTo, SplitCompass, RotateCompass

class CompassExample(Scene):
    def construct(self):
        compass = Compass().to_edge(LEFT)
        self.play(MoveNiddleTipTo(compass, ORIGIN))
        self.play(SplitCompass(compass, 2))
        self.play(RotateCompass(compass, PI / 2))

from manim import *
from manim_extensions.compass import Compass, MoveNiddleTipTo, SplitCompass, RotateCompass

class CompassExample(Scene):
    def construct(self):
        compass = Compass().to_edge(LEFT)
        self.play(MoveNiddleTipTo(compass, ORIGIN))
        self.play(SplitCompass(compass, 2))
        self.play(RotateCompass(compass, PI / 2))

Drawing a line with ruler and pencil

Example: DrawLineExample

from manim import *
from manim_extensions.compass import Ruler, Pencil, PutRuler, MovePencilTipTo, DrawPath

class DrawLineExample(Scene):
    def construct(self):
        ruler = Ruler().to_edge(LEFT)
        pencil = Pencil().to_edge(LEFT)
        path = Line(LEFT, UR)

        self.play(
            PutRuler(ruler, start=LEFT, end=UR),
            MovePencilTipTo(pencil, LEFT),
        )
        self.play(DrawPath(pencil, path))

from manim import *
from manim_extensions.compass import Ruler, Pencil, PutRuler, MovePencilTipTo, DrawPath

class DrawLineExample(Scene):
    def construct(self):
        ruler = Ruler().to_edge(LEFT)
        pencil = Pencil().to_edge(LEFT)
        path = Line(LEFT, UR)

        self.play(
            PutRuler(ruler, start=LEFT, end=UR),
            MovePencilTipTo(pencil, LEFT),
        )
        self.play(DrawPath(pencil, path))

Using CompassScene

For more involved constructions, inherit from CompassScene instead of Scene. It exposes ready-to-use compass, ruler and pencil attributes plus helper methods such as draw_arc and draw_line. See the demo/compass_scene_demo.py file in the upstream repository for a complete example.

See the original README for full animated examples and further details.