Add color utilities (RGB & HCL/CIELCH conversion)

src/main/java/chylex/hee/render/util/ColorSpaces.kt

@@ -0,0 +1,83 @@
+package chylex.hee.render.util
+import chylex.hee.system.util.floorToInt
+import org.lwjgl.util.Color
+import kotlin.math.cos
+import kotlin.math.pow
+import kotlin.math.roundToInt
+import kotlin.math.sin
+
+interface IColor{
+	fun toRGB(): Color
+	
+	fun toInt(alpha: Float? = null): Int{
+		val rgb = toRGB()
+		return (if (alpha == null) 0 else ((alpha * 255).floorToInt() shl 24)) or (rgb.red shl 16) or (rgb.green shl 8) or rgb.blue
+	}
+}
+
+/**
+ * Represents an RGB color.
+ *
+ * @param[red] value between 0-255
+ * @param[green] value between 0-255
+ * @param[blue] value between 0-255
+ */
+data class RGB(val red: Int, val green: Int, val blue: Int) : IColor{
+	constructor(rgb: Int) : this(rgb, rgb, rgb)
+	
+	override fun toRGB(): Color{
+		return Color(red, green, blue)
+	}
+}
+
+/**
+ * Represents a CIELCH color (http://hclwizard.org/hclwizard).
+ *
+ * @param[hue] value between 0-360
+ * @param[chroma] value between 0-100
+ * @param[luminance] value between 0-100
+ */
+data class HCL(val hue: Double, val chroma: Int, val luminance: Int) : IColor{
+	companion object{
+		private const val X_NORMALIZED =  95.047
+		private const val Y_NORMALIZED = 100.000
+		private const val Z_NORMALIZED = 108.883
+		
+		private const val U_NORMALIZED = (4 * X_NORMALIZED) / (X_NORMALIZED + 15 * Y_NORMALIZED + 3 * Z_NORMALIZED)
+		private const val V_NORMALIZED = (9 * Y_NORMALIZED) / (X_NORMALIZED + 15 * Y_NORMALIZED + 3 * Z_NORMALIZED)
+	}
+	
+	override fun toRGB(): Color{
+		val hueRad = Math.toRadians(hue)
+		
+		val l = luminance
+		val u = chroma * cos(hueRad)
+		val v = chroma * sin(hueRad)
+		
+		if (luminance == 0){
+			return Color(0, 0, 0)
+		}
+		
+		val uu = (u / (13.0 * l)) + U_NORMALIZED
+		val vv = (v / (13.0 * l)) + V_NORMALIZED
+		
+		val y = 0.01 * if (l <= 8)
+			Y_NORMALIZED * l * (3.0 / 29.0).pow(3)
+		else
+			Y_NORMALIZED * ((l + 16) / 116.0).pow(3)
+		
+		val x = y * (9 * uu) / (4 * vv)
+		val z = y * (12 - 3 * uu - 20 * vv) / (4 * vv)
+		
+		fun fRGB(c: Double) = if (c <= 0.0031308)
+			c * 12.92
+		else
+			(1.055 * c.pow(1.0 / 2.4)) - 0.055
+		
+		return Color(
+			(fRGB( 3.2404542 * x - 1.5371385 * y - 0.4985314 * z) * 255).roundToInt().coerceIn(0, 255),
+			(fRGB(-0.9692660 * x + 1.8760108 * y + 0.0415560 * z) * 255).roundToInt().coerceIn(0, 255),
+			(fRGB( 0.0556434 * x - 0.2040259 * y + 1.0572252 * z) * 255).roundToInt().coerceIn(0, 255)
+		)
+	}
+}