13 Themed Mathematics🔗ℹ

This recipe makes a small mathematical diagram readable on light and dark backgrounds while keeping one literal institutional color fixed. The code is evaluated when the manual is built.

(define institution-blue (rgb-color 20 70 170))

(define theme-axes

(axes #:id 'axes #:stroke theme-axis))

(define diagram-grid

(axes-grid-lines theme-axes #:id 'grid #:stroke theme-grid))

(define theme-heading

(plain-text "f(x) = x²" #:id 'heading

#:color theme-foreground #:center (vec2 0 3)))

(define theme-badge

(circle #:id 'institution-mark #:radius 1/5

#:fill institution-blue #:stroke institution-blue))

(define diagram

(scene-wait

(scene-add (make-scene) diagram-grid theme-axes theme-heading theme-badge)

1))

(define heat

(diverging-color-scale #:minimum -1 #:maximum 1 #:midpoint 0

#:missing theme-muted))

The same Scene can be rendered under either theme. These two calls differ only in the explicit color theme:

> (scene->pict diagram 0 #:theme animate-light-theme)

> (scene->pict diagram 0 #:theme animate-dark-theme)

> (scene-duration diagram)

1

> (equal? (resolve-color institution-blue animate-light-theme)           (resolve-color institution-blue animate-dark-theme))

#t

Pass diagram unchanged to preview or render settings with animate-light-theme or animate-dark-theme. Semantic roles adapt; institution-blue stays fixed. The diverging scale separately records that zero is a meaningful center.

For a spatial object, material color follows the same rule:

(define material

(material3d #:color theme-surface

#:specular-color theme-highlight

#:emission institution-blue

#:emission-strength 1/10))

> (material3d? material)

#t

The preview’s Material section reports authored material colors and their resolved lighting inputs. It does not describe a final lit pixel as if it were a palette swatch.