video/.agents/skills/manimce-best-practices/rules/styling.md

name, description, metadata

name	description	metadata
styling	Fill, stroke, opacity and visual styling of mobjects	tags fill, stroke, opacity, style, width, appearance

Styling Mobjects

Control the visual appearance of mobjects with fill, stroke, and opacity settings.

Fill Properties

Fill controls the interior of shapes.

from manim import *

class FillExample(Scene):
    def construct(self):
        # Set fill on creation
        circle = Circle(fill_color=BLUE, fill_opacity=0.8)

        # Set fill after creation
        square = Square()
        square.set_fill(RED, opacity=0.5)

        self.add(circle, square)

Fill Methods

mobject.set_fill(color=RED)                    # Color only
mobject.set_fill(RED, opacity=0.5)             # Color and opacity
mobject.set_fill(opacity=0.5)                  # Opacity only
mobject.set_fill_color(RED)                    # Color only (alternative)
mobject.set_fill_opacity(0.5)                  # Opacity only (alternative)

Stroke Properties

Stroke controls the outline/border of shapes.

class StrokeExample(Scene):
    def construct(self):
        # Set stroke on creation
        circle = Circle(stroke_color=BLUE, stroke_width=4)

        # Set stroke after creation
        square = Square()
        square.set_stroke(RED, width=8)

        self.add(circle, square)

Stroke Methods

mobject.set_stroke(color=RED)                  # Color only
mobject.set_stroke(RED, width=4)               # Color and width
mobject.set_stroke(width=4)                    # Width only
mobject.set_stroke(opacity=0.5)                # Opacity only
mobject.set_stroke_color(RED)                  # Color only (alternative)
mobject.set_stroke_width(4)                    # Width only (alternative)
mobject.set_stroke_opacity(0.5)                # Opacity only (alternative)

Stroke Width Reference

# Common stroke widths
DEFAULT_STROKE_WIDTH = 4
thin = 1
normal = 4
thick = 8
very_thick = 12

Combined Styling

class CombinedStyling(Scene):
    def construct(self):
        square = Square()
        square.set_fill(BLUE, opacity=0.5)
        square.set_stroke(YELLOW, width=6)
        self.add(square)

Method Chaining

square = Square().set_fill(RED, 0.5).set_stroke(WHITE, 4)

The set_style Method

Set multiple style properties at once:

square = Square()
square.set_style(
    fill_color=BLUE,
    fill_opacity=0.5,
    stroke_color=WHITE,
    stroke_width=4,
    stroke_opacity=1
)

Opacity

Control transparency of mobjects:

# Overall opacity
mobject.set_opacity(0.5)  # Affects both fill and stroke

# Separate opacities
mobject.set_fill_opacity(0.8)
mobject.set_stroke_opacity(0.3)

# Fade effect
mobject.fade(0.5)  # 0.5 = 50% faded (opposite of opacity)

Background Rectangle

Add a background behind text or other mobjects:

class BackgroundExample(Scene):
    def construct(self):
        text = Text("Important!")
        bg = BackgroundRectangle(text, fill_opacity=0.8, buff=0.1)
        group = VGroup(bg, text)
        self.add(group)

Applying Style to Submobjects

# Apply to all submobjects (family=True, default)
group.set_fill(RED, opacity=0.5, family=True)

# Apply only to parent, not submobjects
group.set_fill(RED, opacity=0.5, family=False)

Style Based on Position

class GradientFill(Scene):
    def construct(self):
        squares = VGroup(*[Square() for _ in range(5)]).arrange(RIGHT)

        for i, sq in enumerate(squares):
            opacity = (i + 1) / 5
            sq.set_fill(BLUE, opacity=opacity)

        self.add(squares)

Copying Style

# Copy style from another mobject
source = Circle().set_fill(RED, 0.5).set_stroke(WHITE, 4)
target = Square()
target.match_style(source)  # Now has same fill and stroke

Best Practices

1. Use fill_opacity for shapes - Fully opaque fills can hide other elements
2. Consistent stroke width - Pick a width and stick with it
3. Contrast fill and stroke - Different colors help definition
4. Use BackgroundRectangle for readability - Behind text on busy backgrounds
5. Chain methods for concise code - But break lines if too long