Backport Starlight patch to lazily init emptiness maps

build.gradle

@@ -99,6 +99,7 @@ dependencies {
     modCompileOnly("team.chisel.ctm:CTM:${ctm_version}")
     modCompileOnly("curse.maven:supermartijncore-454372:4455378")
     modCompileOnly("curse.maven:valhesiastructures-347488:3476252")
+    modCompileOnly files("deps/starlight-1.2.jar")
 }
 
 tasks.withType(JavaCompile) {

src/main/java/org/embeddedt/modernfix/core/config/ModernFixEarlyConfig.java

@@ -46,6 +46,7 @@ public class ModernFixEarlyConfig {
         this.addMixinRule("perf.compress_blockstate", false);
         this.addMixinRule("bugfix.concurrency", true);
         this.addMixinRule("bugfix.edge_chunk_not_saved", true);
+        this.addMixinRule("bugfix.starlight_emptiness", modPresent("starlight"));
         this.addMixinRule("bugfix.packet_leak", false);
         this.addMixinRule("perf.dynamic_structure_manager", true);
         this.addMixinRule("bugfix.mc218112", true);

src/main/java/org/embeddedt/modernfix/mixin/bugfix/starlight_emptiness/StarLightEngineMixin.java

@@ -0,0 +1,34 @@
+package org.embeddedt.modernfix.mixin.bugfix.starlight_emptiness;
+
+import ca.spottedleaf.starlight.common.light.StarLightEngine;
+import net.minecraft.world.level.chunk.ChunkAccess;
+import net.minecraft.world.level.chunk.LevelChunkSection;
+import net.minecraft.world.level.chunk.LightChunkGetter;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Pseudo;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+
+@Mixin(StarLightEngine.class)
+public abstract class StarLightEngineMixin {
+    @Shadow protected abstract LevelChunkSection getChunkSection(int chunkX, int chunkY, int chunkZ);
+
+    @Shadow @Final protected int minSection;
+
+    @Inject(method = "handleEmptySectionChanges(Lnet/minecraft/world/level/chunk/LightChunkGetter;Lnet/minecraft/world/level/chunk/ChunkAccess;[Ljava/lang/Boolean;Z)[Z",
+            at = @At(value = "INVOKE", target = "Lca/spottedleaf/starlight/common/light/StarLightEngine;setEmptinessMapCache(II[Z)V",
+            shift = At.Shift.AFTER))
+    private void lazyInitMapIfNeeded(LightChunkGetter lightAccess, ChunkAccess chunk, Boolean[] emptinessChanges, boolean unlit, CallbackInfoReturnable<int[]> cir) {
+        final int chunkX = chunk.getPos().x;
+        final int chunkZ = chunk.getPos().z;
+        for (int sectionIndex = (emptinessChanges.length - 1); sectionIndex >= 0; --sectionIndex) {
+            if(emptinessChanges[sectionIndex] == null) {
+                final LevelChunkSection section = this.getChunkSection(chunkX, sectionIndex + this.minSection, chunkZ);
+                emptinessChanges[sectionIndex] = section == null || section.isEmpty() ? Boolean.TRUE : Boolean.FALSE;
+            }
+        }
+    }
+}

src/main/resources/modernfix.mixins.json

@@ -7,6 +7,7 @@
   "refmap": "modernfix.refmap.json",
   "mixins": [
     "bugfix.edge_chunk_not_saved.ChunkManagerMixin",
+    "bugfix.starlight_emptiness.StarLightEngineMixin",
     "perf.dynamic_structure_manager.StructureManagerMixin",
     "bugfix.tf_cme_on_load.TwilightForestModMixin",
     "bugfix.refinedstorage.te_bug.ItemExternalStorageProviderMixin",