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manim Learning by Doing - Shape Matching

Popularity：612 ℃/2024-10-01 18:13:32

manimThere are a couple of special applications forShape Matchingobjects, their role is to mark and annotate existing objects, itself is generally not used alone.

Shape MatchingThere are a total of 4 types of objects:

  1. BackgroundRectangle: provide a rectangular background for existing objects
  2. Cross: Mark existing objects with a cross-hatch
  3. SurroundingRectangle: Enclose an object in a rectangular box
  4. Underline: Add an underscore to an object

Shape MatchingThe role of the animation is to highlight some objects in the animation, easy to better express the content of the animation.

1. Main parameters

BackgroundRectangleThe main parameters are:

Parameter name typology clarification
mobject Mobject The object to which the background is added
color Color Color of the background
stroke_width float The thickness of the background border
stroke_opacity float Transparency of the background border
fill_opacity float Transparency of the background
buff float The size of the background, the bigger the buff, the bigger the range of the background

The background is borderless by default, via thestroke_widthparameter to add a border.

CrossThe main parameters are:

Parameter name typology clarification
mobject Mobject Objects that have been cross-marked
stroke_color Color Color of the cross-hairs
stroke_width float Thickness of cross-hairs
scale_factor float Length of cross-hairs

SurroundingRectangleThe main parameters are:

Parameter name typology clarification
mobject Mobject The object that the rectangular box is dimensioned by
color Color Rectangular box color
buff float Spacing between the rectangular box and its contents
corner_radius float Curvature of the sharp corners of rectangular frames

UnderlineThe main parameters are:

Parameter name typology clarification
mobject Mobject Adding underlined objects
buff float Spacing between underscores and objects

2. Examples of use

Shape Matchingobjects are generally simple, and they are mostly used in scenes where they supplement the display of other main objects.

Here's a look at what they do with some examples.

2.1. Example of a rectangular background

manimThe animation in the default is on a black background, which can be changed via theBackgroundRectangleAdds a rectangular background of another color to an object.

Used to highlight or emphasize an object.

# Red background
c = Circle()
BackgroundRectangle(c, color=RED)

# Red background+transparency0.2
c = Circle()
BackgroundRectangle(c, color=RED, fill_opacity=0.2)

# Background with Border
c = Circle()
BackgroundRectangle(
    c,
    color=RED,
    fill_opacity=0.2,
    stroke_width=1,
    stroke_opacity=1,
)

# Background rotation
c = Circle()
b = BackgroundRectangle(
    c,
    color=RED,
    fill_opacity=0.2,
).rotate(PI / 4)

2.2 Examples of cross-marking

The intersection point of the cross mark is the center of the marked object, and the color, thickness and length of the mark can be adjusted.

# Color of markers
c1 = Circle(color=GREEN)
Cross(c1, stroke_color=RED)

c2 = Circle(color=YELLOW)
Cross(c2, stroke_color=BLUE)

c3 = Circle(color=BLUE)
Cross(c3, stroke_color=GREEN)

# Marker thickness
c1 = Circle(color=GREEN)
Cross(c1, stroke_width=2)

c2 = Circle(color=YELLOW)
Cross(c2, stroke_width=5)

c3 = Circle(color=BLUE)
Cross(c3, stroke_width=10)

# Length of markers
c1 = Circle(color=GREEN)
Cross(c1, scale_factor=0.5)

c2 = Circle(color=YELLOW)
Cross(c2, scale_factor=1)

c3 = Circle(color=BLUE)
Cross(c3, scale_factor=2)

2.3. Rectangular Border Example

Rectangular borders are generally used to highlight certain text, the sharp corners of the border and the spacing with the text can be adjusted.

# Border spacing
fu1 = Text("good fortune")
SurroundingRectangle(fu1, buff=0.1)

fu2 = Text("good fortune")
SurroundingRectangle(fu2, buff=0.3)

fu3 = Text("good fortune")
SurroundingRectangle(fu3, buff=0.6)

# Rounded corners for borders
fu1 = Text("good fortune")
SurroundingRectangle(fu1, corner_radius=0.1)

fu2 = Text("good fortune")
SurroundingRectangle(fu2, corner_radius=0.3)

fu3 = Text("good fortune")
SurroundingRectangle(fu3, corner_radius=0.8)

2.4. Underlining example

Underlining is one of the simplest types of markup, not just for Chinese and English characters; it can also be added underneath formulas and graphs.

# Underlining of text
t1 = Text("English")
Underline(t1, color=GREEN)

t2 = Text("Chinese")
Underline(t2, color=BLUE)

t3 = Tex("$a^2+b^2=c^2$")
Underline(t3, color=YELLOW)

# Underlining of graphics
t1 = Square(side_length=1)
Underline(t1, color=GREEN)

t2 = Circle(radius=0.5)
Underline(t2, color=BLUE)

t3 = Star(outer_radius=0.6)
Underline(t3, color=YELLOW)

3. Annexes

The complete code for the article is on a web disk (shape_matcher.py），

Download at.Full Code (Access code: 6872)

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