no day-night cycle on titlescreen demo

src/net/torvald/terrarum/blockproperties/BlockPropUtil.kt

@@ -108,7 +108,7 @@ object BlockPropUtil {
         return when (prop.dynamicLuminosityFunction) {
             1    -> getTorchFlicker(prop)
             2    -> (INGAME.world).globalLight.cpy() // current global light
-            3    -> WeatherMixer.getGlobalLightOfTime(INGAME.world, WorldTime.DAY_LENGTH / 2).cpy() // daylight at noon
+            3    -> WeatherMixer.getGlobalLightOfTimeOfNoon().cpy() // daylight at noon
             4    -> getSlowBreath(prop)
             5    -> getPulsate(prop)
             else -> prop.baseLumCol

src/net/torvald/terrarum/gameworld/WorldTime.kt

@@ -121,6 +121,17 @@ class WorldTime(initTime: Long = 0L) {
     inline val moonPhase: Double
         get() = (TIME_T.plus(1700000L) % LUNAR_CYCLE).toDouble() / LUNAR_CYCLE
 
+    fun getSolarElevationAt(ordinalDay: Int, second: Int): Double {
+        val TIME_T = DAY_LENGTH * ordinalDay + second
+
+        val x = (TIME_T % YEAR_SECONDS).toDouble() / DAY_LENGTH + 15 // decimal days. One full day = 1.0
+        val d = -23.44 * cos(TWO_PI * x / YEAR_DAYS)
+
+        // 51.56 and 23.44 will make yearly min/max elevation to be 75deg
+        // -0.2504264: a number that makes y=min when x=0 (x=0 is midnight)
+        return 51.56 * sin(TWO_PI * (x - 0.2504264)) + d
+    }
+
     val solarElevationDeg: Double
         get() {
             val x = (TIME_T % YEAR_SECONDS).toDouble() / DAY_LENGTH + 15 // decimal days. One full day = 1.0

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

@@ -287,7 +287,7 @@ class TitleScreen(batch: FlippingSpriteBatch) : IngameInstance(batch) {
 
         val forcedTime = 39693
 //        demoWorld.globalLight = WeatherMixer.globalLightNow
-        demoWorld.globalLight = WeatherMixer.getGlobalLightOfTime(demoWorld, forcedTime)
+        demoWorld.globalLight = WeatherMixer.getGlobalLightOfTimeOfNoon()
         demoWorld.updateWorldTime(delta)
 //        WeatherMixer.update(delta, cameraPlayer, demoWorld)
         WeatherMixer.forceTimeAt = forcedTime

src/net/torvald/terrarum/weather/WeatherMixer.kt

@@ -161,9 +161,7 @@ internal object WeatherMixer : RNGConsumer {
 
         // we will not care for nextSkybox for now
         val timeNow = (forceTimeAt ?: world.worldTime.TIME_T.toInt()) % WorldTime.DAY_LENGTH
-        val skyboxColourMap = currentWeather.skyboxGradColourMap
         val daylightClut = currentWeather.daylightClut
-
         // calculate global light
         val globalLight = getGradientColour2(daylightClut, world.worldTime.solarElevationDeg, timeNow)
         globalLightNow.set(globalLight)
@@ -185,7 +183,10 @@ internal object WeatherMixer : RNGConsumer {
 
         gdxBlendNormalStraightAlpha()
 
-        val deg =world.worldTime.solarElevationDeg
+        val deg = if (forceTimeAt != null)
+            world.worldTime.getSolarElevationAt(world.worldTime.ordinalDay, forceTimeAt!!)
+        else
+            world.worldTime.solarElevationDeg
         val degThis = deg.floor()
         val degNext = degThis + if (timeNow < HALF_DAY) 1 else -1 // Skybox.get has internal coerceIn
 
@@ -224,8 +225,11 @@ internal object WeatherMixer : RNGConsumer {
     /**
      * Get a GL of specific time
      */
-    fun getGlobalLightOfTime(world: GameWorld, timeInSec: Int): Cvec =
+    fun getGlobalLightOfTimeOfNoon(): Cvec {
-            getGradientColour(world, currentWeather.skyboxGradColourMap, 2, timeInSec)
+        currentWeather.daylightClut.let { it.get(it.width - 1, 0) }.let {
+            return Cvec(it.r, it.g, it.b, it.a)
+        }
+    }
 
     fun getGradientColour(world: GameWorld, colorMap: GdxColorMap, row: Int, timeInSec: Int): Cvec {
         val dataPointDistance = WorldTime.DAY_LENGTH / colorMap.width