Function colorDistance

colorDistance(rgbA: vec4, rgbB: vec4): number
Computes normalized hue distance [0,1] between two RGB colors (vec4).
- Converts to HSV via RGBtoHSV
- If both colors are achromatic (s == 0), hue distance is 0
- Uses shortest circular hue distance on a 0..360 ring, then normalizes by 180
Parameters
- rgbA: vec4
- rgbB: vec4
Returns number