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https://github.com/curioustorvald/Terrarum.git
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d817c586e9
Former-commit-id: 731df40639ccf1463238f70dd615bd1771eee259 Former-commit-id: fdf00fbe30f876731d9d952b2a65f448b90c7913
66 lines
2.0 KiB
Kotlin
66 lines
2.0 KiB
Kotlin
package net.torvald.colourutil
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import com.jme3.math.FastMath
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import net.torvald.colourutil.CIELabUtil.toLab
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import net.torvald.colourutil.CIELabUtil.toRGB
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import net.torvald.colourutil.CIELabUtil.toXYZ
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import org.newdawn.slick.Color
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/**
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* RGB in this code is always sRGB.
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* reference: http://www.brucelindbloom.com/index.html?Equations.html
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*
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* Created by minjaesong on 16-09-01.
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*/
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object CIELChUtil {
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/** Sweet LCh linear gradient */
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fun getGradient(scale: Float, fromCol: Color, toCol: Color): Color {
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val from = fromCol.toLCh()
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val to = toCol.toLCh()
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val newL = FastMath.interpolateLinear(scale, from.L, to.L)
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val newC = FastMath.interpolateLinear(scale, from.C, to.C)
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val newAlpha = FastMath.interpolateLinear(scale, from.alpha, to.alpha)
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val newH: Float
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if ((from.h - to.h).abs() == FastMath.PI) // exact opposite colour
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return CIELabUtil.getGradient(scale, fromCol, toCol)
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else if ((from.h - to.h).abs() > FastMath.PI) // reflex angle
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newH = FastMath.interpolateLinear(scale, from.h, to.h + FastMath.TWO_PI)
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else
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newH = FastMath.interpolateLinear(scale, from.h, to.h)
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return CIELCh(newL, newC, newH, newAlpha).toRGB()
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}
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fun CIELab.toLCh(): CIELCh {
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val c = (a.sqr() + b.sqr()).sqrt()
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val h = FastMath.atan2(b, a)
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return CIELCh(L, c, h, alpha)
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}
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fun CIELCh.toLab(): CIELab {
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val a = C * FastMath.cos(h)
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val b = C * FastMath.sin(h)
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return CIELab(L, a, b, alpha)
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}
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private fun Color.toLCh() = this.toXYZ().toLab().toLCh()
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private fun CIELCh.toRGB() = this.toLab().toXYZ().toRGB()
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private fun Float.sqr() = this * this
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private fun Float.sqrt() = Math.sqrt(this.toDouble()).toFloat()
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private fun Float.abs() = FastMath.abs(this)
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}
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/**
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* @param L : Luminosity in 0.0 - 1.0
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* @param C : Chroma (saturation) in 0.0 - 1.0
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* @param h : Hue in radian (-pi to pi)
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*/
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data class CIELCh(var L: Float = 0f, var C: Float = 0f, var h: Float = 0f, var alpha: Float = 1f)
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