colorTemperatureToRGB.kt

import kotlin.math.ln
import kotlin.math.pow

fun colorTemperatureToRGB(kelvin: Int): Triple<Float, Float, Float> {

    val temp = kelvin / 100.0

    val red: Double
    val green: Double
    val blue: Double

    if (temp <= 66) {
        red = 255.0

        green = 99.4708025861 * ln(temp) - 161.1195681661

        blue = if (temp <= 19) {
            0.0
        } else {
            138.5177312231 * ln(temp - 10) - 305.0447927307
        }
    } else {
        red = 329.698727446 * (temp - 60).pow(-0.1332047592)
        green = 288.1221695283 * (temp - 60).pow(-0.0755148492)
        blue = 255.0
    }

    return Triple(
        red.toFloat().coerceIn(0f, 255f) / 255f,
        green.toFloat().coerceIn(0f, 255f) / 255f,
        blue.toFloat().coerceIn(0f, 255f) / 255f,
    )
}