Fixed altar detection for the alicorn amulet and make it more efficient by saving the centers of active altars

src/main/java/com/minelittlepony/unicopia/item/AlicornAmuletItem.java

@@ -15,7 +15,7 @@ import com.minelittlepony.unicopia.entity.player.*;
 import com.minelittlepony.unicopia.particle.FollowingParticleEffect;
 import com.minelittlepony.unicopia.particle.ParticleUtils;
 import com.minelittlepony.unicopia.particle.UParticles;
-import com.minelittlepony.unicopia.server.world.Altar;
+import com.minelittlepony.unicopia.server.world.UnicopiaWorldProperties;
 import com.minelittlepony.unicopia.trinkets.TrinketsDelegate;
 import com.minelittlepony.unicopia.util.VecHelper;
 
@@ -41,6 +41,7 @@ import net.minecraft.particle.ParticleEffect;
 import net.minecraft.particle.ParticleTypes;
 import net.minecraft.predicate.entity.EntityPredicates;
 import net.minecraft.registry.tag.DamageTypeTags;
+import net.minecraft.server.world.ServerWorld;
 import net.minecraft.sound.SoundCategory;
 import net.minecraft.text.Text;
 import net.minecraft.util.*;
@@ -192,7 +193,8 @@ public class AlicornAmuletItem extends AmuletItem implements ItemTracker.Trackab
 
         if (entity instanceof PlayerEntity) {
             if (entity.isOnFire() && world.getBlockState(entity.getBlockPos().up()).isOf(Blocks.SOUL_FIRE)) {
-                if (Altar.of(entity.getBlockPos().up()).isValid(world)) {
+                if (UnicopiaWorldProperties.forWorld((ServerWorld)world).isActiveAltar(entity.getBlockPos())
+                    || UnicopiaWorldProperties.forWorld((ServerWorld)world).isActiveAltar(entity.getBlockPos().up())) {
                     if (living.asEntity().getHealth() < 2) {
                         entity.setFireTicks(0);
                         world.removeBlock(entity.getBlockPos().up(), false);

src/main/java/com/minelittlepony/unicopia/server/world/Altar.java

@@ -1,14 +1,10 @@
 package com.minelittlepony.unicopia.server.world;
 
-import java.util.Arrays;
 import java.util.HashSet;
-import java.util.List;
 import java.util.Optional;
 import java.util.Set;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
-import java.util.stream.Stream;
-
 import org.jetbrains.annotations.Nullable;
 
 import com.minelittlepony.unicopia.entity.mob.FloatingArtefactEntity;
@@ -26,6 +22,7 @@ import net.minecraft.nbt.NbtCompound;
 import net.minecraft.nbt.NbtElement;
 import net.minecraft.predicate.entity.EntityPredicates;
 import net.minecraft.registry.tag.BlockTags;
+import net.minecraft.server.world.ServerWorld;
 import net.minecraft.util.BlockRotation;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Box;
@@ -54,10 +51,6 @@ public record Altar(BlockPos origin, Set<BlockPos> pillars) {
     private static final BlockPos PILLAR_A = new BlockPos(INNER_RADIUS, 0,  PILLAR_OFFSET_FROM_CENTER);
     private static final BlockPos PILLAR_B = new BlockPos(INNER_RADIUS, 0, -PILLAR_OFFSET_FROM_CENTER);
 
-    private static final List<BlockPos> PILLAR_OFFSETS = Arrays.stream(BlockRotation.values()).flatMap(rotation -> {
-        return Stream.of(PILLAR_A.rotate(rotation), PILLAR_B.rotate(rotation));
-    }).toList();
-
     public static Optional<Altar> locateAltar(World world, BlockPos startingPoint) {
 
         BlockPos.Mutable mutable = startingPoint.mutableCopy();
@@ -103,10 +96,6 @@ public record Altar(BlockPos origin, Set<BlockPos> pillars) {
         return Optional.empty();
     }
 
-    public static Altar of(BlockPos center) {
-        return new Altar(center, new HashSet<>(PILLAR_OFFSETS.stream().map(p -> p.add(center).up()).toList()));
-    }
-
     private static boolean checkSlab(World world, BlockPos pos) {
         return !PosHelper.any(pos, p -> !isObsidian(world, p), HORIZONTALS);
     }
@@ -154,9 +143,15 @@ public record Altar(BlockPos origin, Set<BlockPos> pillars) {
             removeExisting(null, world, pillar);
             world.spawnEntity(artefact);
         });
+        if (!world.isClient) {
+            UnicopiaWorldProperties.forWorld((ServerWorld)world).addAltar(origin());
+        }
     }
 
     public void tearDown(@Nullable Entity except, World world) {
+        if (!world.isClient) {
+            UnicopiaWorldProperties.forWorld((ServerWorld)world).removeAltar(origin());
+        }
         pillars.forEach(pillar -> removeExisting(except, world, pillar));
     }
 

src/main/java/com/minelittlepony/unicopia/server/world/UnicopiaWorldProperties.java

@@ -1,11 +1,17 @@
 package com.minelittlepony.unicopia.server.world;
 
+import java.util.HashSet;
+import java.util.Set;
+
 import com.minelittlepony.unicopia.Race;
 import com.minelittlepony.unicopia.network.Channel;
 import com.minelittlepony.unicopia.network.MsgSkyAngle;
+import com.minelittlepony.unicopia.util.NbtSerialisable;
 
 import net.minecraft.nbt.NbtCompound;
+import net.minecraft.nbt.NbtElement;
 import net.minecraft.server.world.ServerWorld;
+import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.MathHelper;
 import net.minecraft.world.PersistentState;
 
@@ -16,6 +22,8 @@ public class UnicopiaWorldProperties extends PersistentState {
     private Race defaultRace = Race.UNSET;
     private float tangentalSkyAngle;
 
+    private final Set<BlockPos> activeAltarPositions = new HashSet<>();
+
     public UnicopiaWorldProperties(ServerWorld world) {
         this.world = world;
     }
@@ -24,6 +32,7 @@ public class UnicopiaWorldProperties extends PersistentState {
         this(world);
         defaultRace = Race.fromName(tag.getString("defaultRace"), Race.HUMAN);
         tangentalSkyAngle = tag.getFloat("tangentalSkyAngle");
+        activeAltarPositions.addAll(NbtSerialisable.BLOCK_POS.readAll(tag.getList("activeAltars", NbtElement.COMPOUND_TYPE)).toList());
     }
 
     public Race getDefaultRace() {
@@ -46,10 +55,25 @@ public class UnicopiaWorldProperties extends PersistentState {
         Channel.SERVER_SKY_ANGLE.sendToAllPlayers(new MsgSkyAngle(tangentalSkyAngle), world);
     }
 
+    public void removeAltar(BlockPos center) {
+        activeAltarPositions.remove(center);
+        markDirty();
+    }
+
+    public void addAltar(BlockPos center) {
+        activeAltarPositions.add(center);
+        markDirty();
+    }
+
+    public boolean isActiveAltar(BlockPos center) {
+        return activeAltarPositions.contains(center);
+    }
+
     @Override
     public NbtCompound writeNbt(NbtCompound tag) {
         tag.putString("defaultRace", Race.REGISTRY.getId(defaultRace).toString());
         tag.putFloat("tangentalSkyAngle", tangentalSkyAngle);
+        tag.put("activeAltars", NbtSerialisable.BLOCK_POS.writeAll(activeAltarPositions));
         return tag;
     }