bevy_color: adding 'palettes' module.

[viridia]

Two palettes are added:

• Basic: A basic palette with 16 colors.
• CSS: A palette with the colors from the "extended CSS"/X11/HTML4.0 color names.

[alice-i-cecile]

VGA should be spelled out, and a link would be nice.

[viridia]

Added a link. I don't want to spell it out because the name "video graphics array" is actually confusing.

[alice-i-cecile]

I like namespacing color palettes like this :) And it'll ease the migration. However, I really think we should avoid committing Python code in order to avoid complicating the developer experience.

We should either remove it completely, or swap it for a simple Rust equivalent.

[IceSentry]

I'm not personally familiar with the x11 naming and it seems to me like more people would understand if it was called css instead. As in, name the palette css so people can do css::ALICE_BLUE. I think it would be easier to understand where it comes from.

It's very possible it's just a me thing though.

[rparrett]

IMO, we should link to the spec
https://www.w3.org/TR/css-color-4/#named-colors

[viridia]

Removed python code and changed x11 -> css.

[rparrett]

Out of curiosity, how much precision is actually needed here? This certainly seems like enough at a glance, just curious.

pub const BURLYWOOD: Srgba = Srgba::new(0.871, 0.722, 0.529, 1.0);

Any reason not to just use the original integer values here? Or consistently format with 1 decimal.

/// <div style="background-color:rgb(87.1%, 72.2%, 52.900000000000006%); width: 10px; padding: 10px; border: 1px solid;"></div>

[viridia]

@rparrett My python script rounded everything to the nearest thousandth to make the code prettier. I figured one part in a thousand would be imperceptible to the human eye.

I don't really have an opinion otherwise.

[rparrett]

Seems like thousandths are good enough, hundredths would not be.

[bushrat011899]

I like this. The concept of a colour palette is distinct from the colour types themselves, so I like putting them in separate modules. Also opens up the possibility of adding more palettes with colliding names (e.g. blue in Tailwind might not be the same blue in basic, etc.)

[rparrett]

Just an interesting data point regarding float precision:

Old crimson:

pub const CRIMSON: LegacyColor = LegacyColor::rgb(0.86, 0.08, 0.24);

New crimson:

pub const CRIMSON: Srgba = Srgba::new(0.863, 0.078, 0.235, 1.0);

The increased precision resulted in CI picking up a color change in examples using CRIMSON. I am assuming the new one is actually matching the CSS4 value and the old one is not.

Seeing what I assume is the same situation in the virtual_time example which GOLD to tint a sprite. The increased precision caused a small difference there.

Neat.

[alice-i-cecile]

Yeah, the new colors actually match CSS4 values, to three decimals I believe. They were machine-generated via a Python script originally.

[rparrett]

Yeah, I had previously commented on the precision. Just commenting here to confirm that yes, the third decimal matters.

[viridia]

I saved a copy of the script, but it's not checked in anywhere. The actual colors were cut and pasted from the CSS standard website, and then converted into Rust source code.

[rparrett]

Just to be totally clear, I am saying that things are better now with the increased precision.

[viridia]

Here's a Gist containing the Python script I used to generate the color palettes: https://gist.github.com/viridia/0143965eaa7805145a115b85b04b79fd