mirror of
https://github.com/curioustorvald/Terrarum.git
synced 2026-06-16 21:44:05 +09:00
hosek skybox moved outside of basegame; moonlight impl
This commit is contained in:
minjaesong
240
src/net/torvald/terrarum/clut/Skybox.kt
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240
src/net/torvald/terrarum/clut/Skybox.kt
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package net.torvald.terrarum.clut
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import com.badlogic.gdx.Gdx
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import com.badlogic.gdx.graphics.Pixmap
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import com.badlogic.gdx.graphics.Texture
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import com.badlogic.gdx.graphics.g2d.TextureRegion
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import com.badlogic.gdx.utils.Disposable
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import com.jme3.math.FastMath
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import net.torvald.colourutil.CIEXYZ
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import net.torvald.colourutil.toColor
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import net.torvald.colourutil.toRGB
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import net.torvald.parametricsky.ArHosekSkyModel
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import net.torvald.terrarum.App
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import net.torvald.terrarum.App.printdbg
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import net.torvald.terrarum.abs
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import net.torvald.terrarumsansbitmap.gdx.TextureRegionPack
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import kotlin.math.*
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/**
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* Created by minjaesong on 2023-07-09.
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*/
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object Skybox : Disposable {
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private const val HALF_PI = 1.5707963267948966
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private const val PI = 3.141592653589793
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private const val TWO_PI = 6.283185307179586
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const val gradSize = 64
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private lateinit var gradTexBinLowAlbedo: Array<TextureRegion>
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private lateinit var gradTexBinHighAlbedo: Array<TextureRegion>
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private lateinit var tex: Texture
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private lateinit var texRegions: TextureRegionPack
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private lateinit var texStripRegions: TextureRegionPack
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fun loadlut() {
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tex = Texture(Gdx.files.internal("assets/clut/skybox.png"))
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tex.setFilter(Texture.TextureFilter.Linear, Texture.TextureFilter.Linear)
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texRegions = TextureRegionPack(tex, 2, gradSize - 2, 0, 2, 0, 1)
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texStripRegions = TextureRegionPack(tex, elevCnt, gradSize - 2, 0, 2, 0, 1)
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}
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// use internal LUT
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/*operator fun get(elevationDeg: Double, turbidity: Double, albedo: Double): TextureRegion {
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val elev = elevationDeg.coerceIn(-elevBias, elevBias).times(2.0).roundToInt().plus(150)
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val turb = turbidity.coerceIn(1.0, 10.0).minus(1.0).times(turbDivisor).roundToInt()
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val alb = albedo.coerceIn(0.1, 0.9).minus(0.1).times(turbDivisor).roundToInt()
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return gradTexBinLowAlbedo[elev * turbCnt + turb]
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}*/
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// use external LUT
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operator fun get(elevationDeg: Double, turbidity: Double, albedo: Double): TextureRegion {
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val elev = elevationDeg.coerceIn(-elevMax, elevMax).roundToInt().plus(elevMax).roundToInt()
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val turb = turbidity.coerceIn(1.0, 10.0).minus(1.0).times(turbDivisor).roundToInt()
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val alb = albedo.coerceIn(0.1, 0.9).minus(0.1).times(turbDivisor).roundToInt()
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//printdbg(this, "elev $elevationDeg->$elev; turb $turbidity->$turb; alb $albedo->$alb")
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return texRegions.get(alb * elevCnt + elev, turb)
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}
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fun getUV(elevationDeg: Double, turbidity: Double, albedo: Double): Pair<Texture, FloatArray> {
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val turb = turbidity.coerceIn(1.0, 10.0).minus(1.0).times(turbDivisor).roundToInt()
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val alb = albedo.coerceIn(0.1, 0.9).minus(0.1).times(turbDivisor).roundToInt()
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val region = texStripRegions.get(alb, turb)
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val elev = elevationDeg.coerceIn(-elevMax, elevMax).plus(elevMax).div(elevations.last.toDouble()).div(albedoCnt).times((elevCnt - 1.0) / elevCnt)
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val u = region.u + (0.5f / tex.width) + elev.toFloat() // because of the nature of bilinear interpolation, half pixels from the edges must be discarded
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return tex to floatArrayOf(
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u,
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region.v,
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u,
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region.v2
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)
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}
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private fun Float.scaleFun() =
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(1f - 1f / 2f.pow(this/6f)) * 0.97f
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internal fun CIEXYZ.scaleToFit(elevationDeg: Double): CIEXYZ {
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return if (elevationDeg >= 0) {
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CIEXYZ(
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this.X.scaleFun(),
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this.Y.scaleFun(),
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this.Z.scaleFun(),
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this.alpha
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)
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}
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else {
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val deg1 = (-elevationDeg / elevMax).pow(0.93).times(-elevMax)
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val elevation1 = -deg1
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val elevation2 = -deg1 / 28.5
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val scale = (1f - (1f - 1f / 1.8.pow(elevation1)) * 0.97f).toFloat()
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val scale2 = (1.0 - (elevation2.pow(E) / E.pow(elevation2))*0.8).toFloat()
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CIEXYZ(
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this.X.scaleFun() * scale * scale2,
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this.Y.scaleFun() * scale * scale2,
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this.Z.scaleFun() * scale * scale2,
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this.alpha
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)
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}
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}
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val elevations = (0..150)
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val elevMax = elevations.last / 2.0
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val elevationsD = elevations.map { -elevMax + it } // -75, -74, -73, ..., 74, 75 // (specifically using whole number of angles because angle units any finer than 1.0 would make "hack" sunsut happen too fast)
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val turbidities = (0..45) // 1, 1.2, 1.4, 1.6, ..., 10.0
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val turbDivisor = 5.0
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val turbiditiesD = turbidities.map { 1.0 + it / turbDivisor }
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val albedos = arrayOf(0.1, 0.3, 0.5, 0.7, 0.9)
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val elevCnt = elevations.count()
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val turbCnt = turbidities.count()
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val albedoCnt = albedos.size
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val albedoLow = 0.1
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val albedoHight = 0.8 // for theoretical "winter wonderland"?
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val gamma = HALF_PI
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internal fun Double.mapCircle() = sin(HALF_PI * this)
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internal fun initiate() {
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printdbg(this, "Initialising skybox model")
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gradTexBinLowAlbedo = getTexturmaps(albedoLow)
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gradTexBinHighAlbedo = getTexturmaps(albedoHight)
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App.disposables.add(this)
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printdbg(this, "Skybox model generated!")
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}
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/**
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* See https://www.desmos.com/calculator/lcvvsju3p1 for mathematical definition
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* @param p decay point. 0.0..1.0
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* @param q polynomial degree. 2+. Larger value means sharper transition around the point p
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* @param x the 'x' value of the function, as in `y=f(x)`. 0.0..1.0
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*/
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internal fun polynomialDecay(p: Double, q: Int, x: Double): Double {
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val sign = if (q % 2 == 1) -1 else 1
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val a1 = -1.0 / p
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val a2 = 1.0 / (1.0 - p)
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val q = q.toDouble()
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return if (x < p)
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sign * a1.pow(q - 1.0) * x.pow(q) + 1.0
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else
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sign * a2.pow(q - 1.0) * (x - 1.0).pow(q)
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}
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internal fun polynomialDecay2(p: Double, q: Int, x: Double): Double {
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val sign = if (q % 2 == 1) 1 else -1
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val a1 = -1.0 / p
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val a2 = 1.0 / (1.0 - p)
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val q = q.toDouble()
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return if (x < p)
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sign * a1.pow(q - 1.0) * x.pow(q)
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else
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sign * a2.pow(q - 1.0) * (x - 1.0).pow(q) + 1.0
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}
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internal fun superellipsoidDecay(p: Double, x: Double): Double {
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return 1.0 - (1.0 - (1.0 - x).pow(1.0 / p)).pow(p)
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}
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internal fun Double.coerceInSmoothly(low: Double, high: Double): Double {
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val x = this.coerceIn(low, high)
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val x2 = ((x - low) * (high - low).pow(-1.0))
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// return FastMath.interpolateLinear(polynomialDecay2(0.5, 2, x2), low, high)
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return FastMath.interpolateLinear(smoothLinear(0.2, x2), low, high)
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}
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/**
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* To get the idea what the fuck is going on here, please refer to https://www.desmos.com/calculator/snqglcu2wl
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*/
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internal fun smoothLinear(p: Double, x0: Double): Double {
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val x = x0 - 0.5
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val p1 = sqrt(1.0 - 2.0 * p)
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val t = 0.5 * p1
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val y0 = if (x < -t)
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(1.0 / p) * (x + 0.5).pow(2) - 0.5
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else if (x > t)
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-(1.0 / p) * (x - 0.5).pow(2) + 0.5
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else
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x * 2.0 / (1.0 + p1)
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return y0 + 0.5
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}
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private fun getTexturmaps(albedo: Double): Array<TextureRegion> {
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return Array(elevCnt * turbCnt) {
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val elevationDeg = elevationsD[it / turbCnt]
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val elevationRad = Math.toRadians(elevationDeg)
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val turbidity = turbiditiesD[it % turbCnt]
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val state = ArHosekSkyModel.arhosek_xyz_skymodelstate_alloc_init(turbidity, albedo, elevationRad.abs())
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val pixmap = Pixmap(1, gradSize, Pixmap.Format.RGBA8888)
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// printdbg(this, "elev $elevationDeg turb $turbidity")
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for (yp in 0 until gradSize) {
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val yi = yp - 3
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val xf = -elevationDeg / 90.0
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var yf = (yi / 58.0).coerceIn(0.0, 1.0).mapCircle().coerceInSmoothly(0.0, 0.95)
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// experiments visualisation: https://www.desmos.com/calculator/5crifaekwa
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// if (elevationDeg < 0) yf *= 1.0 - pow(xf, 0.333)
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// if (elevationDeg < 0) yf *= -2.0 * asin(xf - 1.0) / PI
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if (elevationDeg < 0) yf *= superellipsoidDecay(1.0 / 3.0, xf)
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val theta = yf * HALF_PI
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// vertical angle, where 0 is zenith, ±90 is ground (which is odd)
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// println("$yp\t$theta")
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val xyz = CIEXYZ(
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ArHosekSkyModel.arhosek_tristim_skymodel_radiance(state, theta, gamma, 0).toFloat(),
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ArHosekSkyModel.arhosek_tristim_skymodel_radiance(state, theta, gamma, 1).toFloat(),
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ArHosekSkyModel.arhosek_tristim_skymodel_radiance(state, theta, gamma, 2).toFloat()
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)
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val xyz2 = xyz.scaleToFit(elevationDeg)
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val rgb = xyz2.toRGB().toColor()
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// pixmap.setColor(if (yp in 17 until 17 + 94) Color.LIME else Color.CORAL)
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pixmap.setColor(rgb)
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pixmap.drawPixel(0, yp)
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}
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val texture = Texture(pixmap).also {
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it.setFilter(Texture.TextureFilter.Linear, Texture.TextureFilter.Linear)
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}
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pixmap.dispose()
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TextureRegion(texture)
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}
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}
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override fun dispose() {
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if (Skybox::gradTexBinLowAlbedo.isInitialized) gradTexBinLowAlbedo.forEach { it.texture.dispose() }
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if (Skybox::gradTexBinHighAlbedo.isInitialized) gradTexBinHighAlbedo.forEach { it.texture.dispose() }
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if (Skybox::tex.isInitialized) tex.dispose()
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}
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}
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