hosek skybox moved outside of basegame; moonlight impl

2026-06-14 12:34:05 +09:00 · 2023-08-04 13:43:14 +09:00
parent 9fe6618cc9
commit 18631064d4
10 changed files with 43 additions and 55 deletions
--- a/src/net/torvald/terrarum/clut/GenerateSkyboxTextureAtlas.kt
+++ b/src/net/torvald/terrarum/clut/GenerateSkyboxTextureAtlas.kt
@@ -0,0 +1,99 @@
+package net.torvald.terrarum.clut
+
+import net.torvald.colourutil.CIEXYZ
+import net.torvald.colourutil.toColor
+import net.torvald.colourutil.toRGB
+import net.torvald.parametricsky.ArHosekSkyModel
+import net.torvald.terrarum.abs
+import net.torvald.terrarum.clut.Skybox.coerceInSmoothly
+import net.torvald.terrarum.clut.Skybox.mapCircle
+import net.torvald.terrarum.clut.Skybox.scaleToFit
+import net.torvald.terrarum.modulebasegame.worldgenerator.HALF_PI
+import net.torvald.terrarum.serialise.toLittle
+import java.io.File
+
+/**
+ * Created by minjaesong on 2023-08-01.
+ */
+fun main() {
+    // y: increasing turbidity (1.0 .. 10.0, in steps of 0.333)
+    // x: elevations (-75 .. 75 in steps of 1, then albedo of [0.1, 0.3, 0.5, 0.7, 0.9])
+    val texh = Skybox.gradSize * Skybox.turbCnt
+    val texw = Skybox.elevCnt * Skybox.albedoCnt
+    val TGA_HEADER_SIZE = 18
+
+    val bytes = ByteArray(TGA_HEADER_SIZE + texw * texh * 4 + 26)
+    // write header
+    byteArrayOf(
+        0, // ID field
+        0, // colour map (none)
+        2, // colour type (unmapped RGB)
+        0,0,0,0,0, // colour map spec (empty)
+        0,0, // x origin (0)
+        0,0, // y origin (0)
+        (texw and 255).toByte(),(texw.ushr(8) and 255).toByte(), // width
+        (texh and 255).toByte(),(texh.ushr(8) and 255).toByte(), // height
+        32, // bits-per-pixel (8bpp RGBA)
+        8 // image descriptor
+    ).forEachIndexed { i,b -> bytes[i] = b }
+    // write footer
+    "\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000TRUEVISION-XFILE\u002E\u0000".forEachIndexed { i, c -> bytes[18 + texw * texh * 4 + i] =
+        c.code.toByte()
+    }
+
+    println("Generating texture atlas ($texw x $texh)...")
+
+    // write pixels
+    for (albedo0 in 0 until Skybox.albedoCnt) {
+        val albedo = Skybox.albedos[albedo0]
+        println("Albedo=$albedo")
+        for (turb0 in 0 until Skybox.turbCnt) {
+            val turbidity = Skybox.turbiditiesD[turb0]
+            println("....... Turbidity=$turbidity")
+            for (elev0 in 0 until Skybox.elevCnt) {
+                val elevationDeg = Skybox.elevationsD[elev0]
+                val elevationRad = Math.toRadians(elevationDeg)
+//                println("... Elevation: $elevationDeg")
+
+                val state = ArHosekSkyModel.arhosek_xyz_skymodelstate_alloc_init(turbidity, albedo, elevationRad.abs())
+
+                for (yp in 0 until Skybox.gradSize) {
+                    val yi = yp - 3
+                    val xf = -elevationDeg / 90.0
+                    var yf = (yi / 58.0).coerceIn(0.0, 1.0).mapCircle().coerceInSmoothly(0.0, 0.95)
+
+                    // experiments visualisation: https://www.desmos.com/calculator/5crifaekwa
+//                    if (elevationDeg < 0) yf *= 1.0 - pow(xf, 0.333)
+//                    if (elevationDeg < 0) yf *= -2.0 * asin(xf - 1.0) / PI
+                    if (elevationDeg < 0) yf *= Skybox.superellipsoidDecay(1.0 / 3.0, xf)
+                    val theta = yf * HALF_PI
+                    // vertical angle, where 0 is zenith, ±90 is ground (which is odd)
+
+//                    println("$yp\t$theta")
+
+                    val xyz = CIEXYZ(
+                        ArHosekSkyModel.arhosek_tristim_skymodel_radiance(state, theta, HALF_PI, 0).toFloat(),
+                        ArHosekSkyModel.arhosek_tristim_skymodel_radiance(state, theta, HALF_PI, 1).toFloat(),
+                        ArHosekSkyModel.arhosek_tristim_skymodel_radiance(state, theta, HALF_PI, 2).toFloat()
+                    )
+                    val xyz2 = xyz.scaleToFit(elevationDeg)
+                    val rgb = xyz2.toRGB().toColor()
+                    val colour = rgb.toIntBits().toLittle()
+
+                    val imgOffX = (albedo0 * Skybox.elevCnt + elev0)
+                    val imgOffY = texh - 1 - (Skybox.gradSize * turb0 + yp)
+                    val fileOffset = TGA_HEADER_SIZE + 4 * (imgOffY * texw + imgOffX)
+                    for (i in 0..3) {
+                        bytes[fileOffset + i] = colour[bytesLut[i]]
+                    }
+                }
+            }
+        }
+    }
+
+    println("Atlas generation done!")
+
+    File("./assets/mods/basegame/weathers/main_skybox.tga").writeBytes(bytes)
+}
+
+private val bytesLut = arrayOf(2,1,0,3,2,1,0,3) // For some reason BGRA order is what makes it work