Classify colors as warm or cool
Use a signed hue score while keeping the neutral boundary visible.
oklch hue 30 - score 0.667
warm
oklch hue 90 - score 0
neutral
oklch hue 210 - score -0.667
cool
Keep zero as its own state
isHot() tests for a positive score and isCold() for a negative score. A score of exactly zero satisfies neither predicate.
Inspect the score behind the booleans
temperature() maps OKLCH hue to a signed value from -1 to 1. The booleans only test its sign.
<?php
use PhpColor\Color\OklchColor;
foreach ([30.0, 90.0, 210.0] as $hue) {
$color = new OklchColor(0.7, 0.15, $hue);
printf("%s %.6f hot=%d cold=%d\n",
$color->toHex(),
$color->temperature(),
$color->isHot(),
$color->isCold(),
);
}
// #ed7665 0.666667 hot=1 cold=0
// #c39900 0.000000 hot=0 cold=0
// #00b6d1 -0.666667 hot=0 cold=1Temperature is a project classification
The score describes hue placement. It is not a physical light temperature, a kelvin value, or a universal semantic judgment.
Warmtemperature() is greater than zero.
Cooltemperature() is less than zero.
NeutralA zero score is neither hot nor cold.
Achromatic colorsA hue coordinate can remain numerically present when chroma is near zero.