deploying new skybox model

src/net/torvald/terrarum/modulebasegame/TerrarumIngame.kt

@@ -28,6 +28,7 @@ import net.torvald.terrarum.gameparticles.ParticleBase
 import net.torvald.terrarum.gameworld.GameWorld
 import net.torvald.terrarum.gameworld.WorldSimulator
 import net.torvald.terrarum.langpack.Lang
+import net.torvald.terrarum.modulebasegame.clut.Skybox
 import net.torvald.terrarum.modulebasegame.gameactors.*
 import net.torvald.terrarum.modulebasegame.gameactors.physicssolver.CollisionSolver
 import net.torvald.terrarum.modulebasegame.gameitems.PickaxeCore

src/net/torvald/terrarum/modulebasegame/TitleScreen.kt

@@ -27,6 +27,7 @@ import net.torvald.terrarum.gameworld.GameWorld
 import net.torvald.terrarum.gameworld.WorldTime
 import net.torvald.terrarum.gameworld.fmod
 import net.torvald.terrarum.langpack.Lang
+import net.torvald.terrarum.modulebasegame.clut.Skybox
 import net.torvald.terrarum.modulebasegame.ui.UILoadGovernor
 import net.torvald.terrarum.modulebasegame.ui.UIRemoCon
 import net.torvald.terrarum.modulebasegame.ui.UITitleRemoConYaml
@@ -239,6 +240,7 @@ class TitleScreen(batch: FlippingSpriteBatch) : IngameInstance(batch) {
         uiContainer.add(uiRemoCon)
 
         CommandDict // invoke
+        Skybox // invoke
         // TODO add console here
 
 

src/net/torvald/terrarum/modulebasegame/clut/Skybox.kt

@@ -1,16 +1,123 @@
 package net.torvald.terrarum.modulebasegame.clut
 
+import com.badlogic.gdx.graphics.Pixmap
 import com.badlogic.gdx.graphics.Texture
+import com.badlogic.gdx.utils.Disposable
+import net.torvald.colourutil.CIEXYZ
+import net.torvald.colourutil.toColor
+import net.torvald.colourutil.toRGB
+import net.torvald.parametricsky.ArHosekSkyModel
+import net.torvald.terrarum.App
+import net.torvald.terrarum.App.printdbg
+import net.torvald.terrarum.abs
+import net.torvald.terrarum.modulebasegame.worldgenerator.HALF_PI
+import kotlin.math.*
 
 /**
  * Created by minjaesong on 2023-07-09.
  */
-object Skybox {
+object Skybox : Disposable {
 
-    const val gradSize = 64
+    const val gradSize = 128
 
-    operator fun get(elevation: Double, turbidity: Double): Array<Texture> {
-        TODO()
+    private val gradTexBin: Array<Texture>
+
+    operator fun get(elevationDeg: Double, turbidity: Double): Texture {
+//        if (elevationDeg !in elevationsD) {
+//            throw IllegalArgumentException("Elevation not in ±75° (got $elevationDeg)")
+//        }
+//        if (turbidity !in turbiditiesD) {
+//            throw IllegalArgumentException("Turbidity not in 1..10 (got $turbidity)")
+//        }
+
+        val elev = elevationDeg.coerceIn(elevationsD).toInt() - elevations.first
+        val turb = ((turbidity.coerceIn(turbiditiesD) - turbiditiesD.start) / (turbidities.step / 100.0)).toInt()
+
+//        printdbg(this, "$elevationDeg $turbidity ; $elev $turb")
+
+        return gradTexBin[elev * turbCnt + turb]
     }
 
+    private fun Float.scaleFun() =
+        (1f - 1f / 2f.pow(this/6f)) * 0.97f
+
+    private fun CIEXYZ.scaleToFit(elevationDeg: Double): CIEXYZ {
+        return if (elevationDeg >= 0) {
+            CIEXYZ(
+                this.X.scaleFun(),
+                this.Y.scaleFun(),
+                this.Z.scaleFun(),
+                this.alpha
+            )
+        }
+        else {
+            val elevation1 = -elevationDeg
+            val elevation2 = -elevationDeg / 28.5
+            val scale = (1f - (1f - 1f / 1.8.pow(elevation1)) * 0.97f).toFloat()
+            val scale2 = (1.0 - (elevation2.pow(E) / E.pow(elevation2))*0.8).toFloat()
+            CIEXYZ(
+                this.X.scaleFun() * scale * scale2,
+                this.Y.scaleFun() * scale * scale2,
+                this.Z.scaleFun() * scale * scale2,
+                this.alpha
+            )
+        }
+    }
+
+    private val elevations = (-75..75) // 151
+    private val elevationsD = (elevations.first.toDouble() .. elevations.last.toDouble())
+    private val turbidities = (1_00..10_00 step 50) // 19
+    private val turbiditiesD = (turbidities.first / 100.0..turbidities.last / 100.0)
+    private val elevCnt = elevations.count()
+    private val turbCnt = turbidities.count()
+    private val albedo = 0.1
+    private val gamma = HALF_PI
+
+    private fun Double.mapCircle() = sin(HALF_PI * this)
+
+    init {
+        printdbg(this, "Initialising skybox model")
+
+        gradTexBin = Array(elevCnt * turbCnt) {
+
+            val elevationDeg = (it / turbCnt).plus(elevations.first).toDouble()
+            val elevationRad = Math.toRadians(elevationDeg)
+            val turbidity = 1.0 + (it % turbCnt) / 100.0
+
+            val state = ArHosekSkyModel.arhosek_xyz_skymodelstate_alloc_init(turbidity, albedo, elevationRad.abs())
+            val pixmap = Pixmap(1, gradSize, Pixmap.Format.RGBA8888)
+
+//            printdbg(this, "elev $elevationDeg turb $turbidity")
+
+            for (y in 0 until gradSize) {
+                val theta = (y.toDouble() / gradSize * 1.0).coerceIn(0.0, 1.0).mapCircle() * HALF_PI
+                // vertical angle, where 0 is zenith, ±90 is ground (which is odd)
+
+                val xyz = CIEXYZ(
+                    ArHosekSkyModel.arhosek_tristim_skymodel_radiance(state, theta, gamma, 0).toFloat(),
+                    ArHosekSkyModel.arhosek_tristim_skymodel_radiance(state, theta, gamma, 1).toFloat(),
+                    ArHosekSkyModel.arhosek_tristim_skymodel_radiance(state, theta, gamma, 2).toFloat()
+                )
+                val xyz2 = xyz.scaleToFit(elevationDeg)
+                val rgb = xyz2.toRGB().toColor()
+
+                pixmap.setColor(rgb)
+                pixmap.drawPixel(0, gradSize - 1 - y)
+            }
+
+            val texture = Texture(pixmap).also {
+                it.setFilter(Texture.TextureFilter.Linear, Texture.TextureFilter.Linear)
+            }
+            pixmap.dispose()
+            texture
+        }
+
+        App.disposables.add(this)
+
+        printdbg(this, "Skybox model generated!")
+    }
+
+    override fun dispose() {
+        gradTexBin.forEach { it.dispose() }
+    }
 }