scales.ts

1	/**
2	* Slider mappings shared by the panel and the views.
3	*
4	* This lives outside views/ on purpose: the panel needs the eye-height scale to
5	* label its slider before the interior view exists, and importing the view for it
6	* would statically pull Three.js into the entry chunk — the exact regression
7	* D-021 fixed for the exterior.
8	*/
9
10	/** Standing eye height. */
11	export const EYE_MIN_M = 1.7
12	/** High enough to be a fifth of the way to the axis, and see the world as a tube. */
13	export const EYE_MAX_M = 25_000
14
15	/** Eye height from a 0..1 slider position. Logarithmic, so 1.7 m is reachable. */
16	export const eyeHeightFromSlider = (v: number): number =>
17	EYE_MIN_M * (EYE_MAX_M / EYE_MIN_M) ** Math.min(1, Math.max(0, v))
18
19	export const sliderFromEyeHeight = (h: number): number =>
20	Math.log(Math.max(EYE_MIN_M, h) / EYE_MIN_M) / Math.log(EYE_MAX_M / EYE_MIN_M)