Configurable xp orb merge group count (#12503)

paper-server/patches/sources/net/minecraft/world/entity/ExperienceOrb.java.patch

@@ -97,7 +97,7 @@
              Vec3 vec3 = new Vec3(
                  this.followingPlayer.getX() - this.getX(),
                  this.followingPlayer.getY() + this.followingPlayer.getEyeHeight() / 2.0 - this.getY(),
-@@ -161,16 +_,27 @@
+@@ -161,18 +_,29 @@
      }
  
      public static void award(ServerLevel level, Vec3 pos, int amount) {
@@ -124,9 +124,17 @@
      private static boolean tryMergeToExisting(ServerLevel level, Vec3 pos, int amount) {
 +        // Paper - TODO some other event for this kind of merge
          AABB aabb = AABB.ofSize(pos, 1.0, 1.0, 1.0);
-         int randomInt = level.getRandom().nextInt(40);
+-        int randomInt = level.getRandom().nextInt(40);
++        int randomInt = level.getRandom().nextInt(io.papermc.paper.configuration.GlobalConfiguration.get().misc.xpOrbGroupsPerArea.or(ORB_GROUPS_PER_AREA)); // Paper - Configure how many orb groups per area
          List<ExperienceOrb> entities = level.getEntities(EntityTypeTest.forClass(ExperienceOrb.class), aabb, orb -> canMerge(orb, randomInt, amount));
-@@ -193,9 +_,14 @@
+         if (!entities.isEmpty()) {
+             ExperienceOrb experienceOrb = entities.get(0);
+@@ -189,13 +_,18 @@
+     }
+ 
+     private static boolean canMerge(ExperienceOrb orb, int amount, int other) {
+-        return !orb.isRemoved() && (orb.getId() - amount) % 40 == 0 && orb.getValue() == other;
++        return !orb.isRemoved() && (orb.getId() - amount) % io.papermc.paper.configuration.GlobalConfiguration.get().misc.xpOrbGroupsPerArea.or(ORB_GROUPS_PER_AREA) == 0 && orb.getValue() == other; // Paper - Configure how many orbs will merge together
      }
  
      private void merge(ExperienceOrb orb) {

paper-server/src/main/java/io/papermc/paper/configuration/Configurations.java

@@ -62,7 +62,8 @@ public abstract class Configurations<G, W> {
     protected ObjectMapper.Factory.Builder createObjectMapper() {
         return ObjectMapper.factoryBuilder()
             .addConstraint(Constraint.class, new Constraint.Factory())
-            .addConstraint(Constraints.Min.class, Number.class, new Constraints.Min.Factory());
+            .addConstraint(Constraints.Min.class, Number.class, new Constraints.Min.Factory())
+            .addConstraint(Constraints.Max.class, Number.class, new Constraints.Max.Factory());
     }
 
     protected YamlConfigurationLoader.Builder createLoaderBuilder() {

paper-server/src/main/java/io/papermc/paper/configuration/GlobalConfiguration.java

@@ -356,6 +356,9 @@ public class GlobalConfiguration extends ConfigurationPart {
         public IntOr.Default compressionLevel = IntOr.Default.USE_DEFAULT;
         @Comment("Defines the leniency distance added on the server to the interaction range of a player when validating interact packets.")
         public DoubleOr.Default clientInteractionLeniencyDistance = DoubleOr.Default.USE_DEFAULT;
+        @Comment("Defines how many orbs groups can exist in an area.")
+        @Constraints.Min(1)
+        public IntOr.Default xpOrbGroupsPerArea = IntOr.Default.USE_DEFAULT;
     }
 
     public BlockUpdates blockUpdates;

paper-server/src/main/java/io/papermc/paper/configuration/constraint/Constraints.java

@@ -40,4 +40,22 @@ public final class Constraints {
             }
         }
     }
+
+    @Documented
+    @Retention(RetentionPolicy.RUNTIME)
+    @Target(ElementType.FIELD)
+    public @interface Max {
+        int value();
+
+        final class Factory implements Constraint.Factory<Max, Number> {
+            @Override
+            public Constraint<Number> make(Max data, Type type) {
+                return value -> {
+                    if (value != null && value.intValue() > data.value()) {
+                        throw new SerializationException(value + " is greater than the max " + data.value());
+                    }
+                };
+            }
+        }
+    }
 }