Is there really no mod that changes the color selector into HSV instead of RGB? RGB is a terrible scheme for selection color, even setting simple colors require you to move multiple sliders. And finding any "non-main" color is a nightmare. I'm honestly kinda surprised that they don't have a setting for switching this in the options.
Is this just a part of the UI that is impossible to mod?
HSV Color
Re: HSV Color
While we're talking color models, I would go with Oklab or Oklch rather than HSV, but in general a model that directly represents hue is almost always a better tool for actual humans to work with.
Another thing to consider is that exposing the full 24-bit RGB range to the player is already full overkill, and somewhat a lie. The actual in-game color comes out 1. desaturated, 2. with lightness on each pixel adjusted to represent the fine details on the in-game model (trains, spiders, player characters, etc) - which obviously helps the game look good, but you won't find a single #ff0000 pixel on an #ff0000 lamp or locomotive. So most games provide players with limited color palettes that mostly vary the hue (e.g. Minecraft has 16 color options: a dozen hues and a couple shades of gray), because the actual difference between #f20000 and #f30000 is virtually imperceptible, even without the saturation/lightness transformations.
For an actual color picker GUI, I really like this wheel picker for oklab - the wheel includes color saturation, showing the relationship between what a "more dirty" version of that color would look like. So that players obsessed with color-matching things together could work out how to make the lamp match the train.
Another thing to consider is that exposing the full 24-bit RGB range to the player is already full overkill, and somewhat a lie. The actual in-game color comes out 1. desaturated, 2. with lightness on each pixel adjusted to represent the fine details on the in-game model (trains, spiders, player characters, etc) - which obviously helps the game look good, but you won't find a single #ff0000 pixel on an #ff0000 lamp or locomotive. So most games provide players with limited color palettes that mostly vary the hue (e.g. Minecraft has 16 color options: a dozen hues and a couple shades of gray), because the actual difference between #f20000 and #f30000 is virtually imperceptible, even without the saturation/lightness transformations.
For an actual color picker GUI, I really like this wheel picker for oklab - the wheel includes color saturation, showing the relationship between what a "more dirty" version of that color would look like. So that players obsessed with color-matching things together could work out how to make the lamp match the train.
Both #FF0000.