Merge tweaks and configuration

This allows the merging of Experience orbs, as well as the configuration of the merge radius of items. Additionally it refactors the merge algorithm to be a better experience for players.

By: md_5 <git@md-5.net>

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

@@ -109,7 +109,28 @@
              }
  
          }
-@@ -287,11 +306,16 @@
+@@ -229,7 +248,10 @@
+ 
+     private void mergeWithNeighbours() {
+         if (this.isMergable()) {
+-            List<ItemEntity> list = this.level().getEntitiesOfClass(ItemEntity.class, this.getBoundingBox().inflate(0.5D, 0.0D, 0.5D), (entityitem) -> {
++            // Spigot start
++            double radius = this.level().spigotConfig.itemMerge;
++            List<ItemEntity> list = this.level().getEntitiesOfClass(ItemEntity.class, this.getBoundingBox().inflate(radius, radius - 0.5D, radius), (entityitem) -> {
++                // Spigot end
+                 return entityitem != this && entityitem.isMergable();
+             });
+             Iterator iterator = list.iterator();
+@@ -259,7 +281,7 @@
+         ItemStack itemstack1 = other.getItem();
+ 
+         if (Objects.equals(this.target, other.target) && ItemEntity.areMergable(itemstack, itemstack1)) {
+-            if (itemstack1.getCount() < itemstack.getCount()) {
++            if (true || itemstack1.getCount() < itemstack.getCount()) { // Spigot
+                 ItemEntity.merge(this, itemstack, other, itemstack1);
+             } else {
+                 ItemEntity.merge(other, itemstack1, this, itemstack);
+@@ -287,11 +309,16 @@
      }
  
      private static void merge(ItemEntity targetEntity, ItemStack targetStack, ItemEntity sourceEntity, ItemStack sourceStack) {
@@ -127,7 +148,7 @@
          }
  
      }
-@@ -320,12 +344,17 @@
+@@ -320,12 +347,17 @@
          } else if (!this.getItem().canBeHurtBy(source)) {
              return false;
          } else {
@@ -146,7 +167,7 @@
              }
  
              return true;
-@@ -382,22 +411,62 @@
+@@ -382,22 +414,62 @@
          }
  
          if (this.getItem().isEmpty()) {
@@ -163,7 +184,7 @@
              ItemStack itemstack = this.getItem();
              Item item = itemstack.getItem();
              int i = itemstack.getCount();
- 
++
 +            // CraftBukkit start - fire PlayerPickupItemEvent
 +            int canHold = player.getInventory().canHold(itemstack);
 +            int remaining = i - canHold;
@@ -178,7 +199,7 @@
 +                    itemstack.setCount(i); // SPIGOT-5294 - restore count
 +                    return;
 +                }
-+
+ 
 +                // Call newer event afterwards
 +                EntityPickupItemEvent entityEvent = new EntityPickupItemEvent((Player) player.getBukkitEntity(), (org.bukkit.entity.Item) this.getBukkitEntity(), remaining);
 +                entityEvent.setCancelled(!entityEvent.getEntity().getCanPickupItems());

paper-server/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java

@@ -703,6 +703,23 @@ public class CraftEventFactory {
             return false;
         }
 
+        // Spigot start - SPIGOT-7523: Merge after spawn event and only merge if the event was not cancelled (gets checked above)
+        if (entity instanceof net.minecraft.world.entity.ExperienceOrb xp) {
+            double radius = world.spigotConfig.expMerge;
+            if (radius > 0) {
+                List<Entity> entities = world.getEntities(entity, entity.getBoundingBox().inflate(radius, radius, radius));
+                for (Entity e : entities) {
+                    if (e instanceof net.minecraft.world.entity.ExperienceOrb loopItem) {
+                        if (!loopItem.isRemoved()) {
+                            xp.value += loopItem.value;
+                            loopItem.discard(null); // Add Bukkit remove cause
+                        }
+                    }
+                }
+            }
+        }
+        // Spigot end
+
         return true;
     }
 

paper-server/src/main/java/org/spigotmc/SpigotWorldConfig.java

@@ -134,4 +134,18 @@ public class SpigotWorldConfig
         this.weepingVinesModifier = this.getAndValidateGrowth( "WeepingVines" );
         this.caveVinesModifier = this.getAndValidateGrowth( "CaveVines" );
     }
+
+    public double itemMerge;
+    private void itemMerge()
+    {
+        this.itemMerge = this.getDouble("merge-radius.item", 2.5 );
+        this.log( "Item Merge Radius: " + this.itemMerge );
+    }
+
+    public double expMerge;
+    private void expMerge()
+    {
+        this.expMerge = this.getDouble("merge-radius.exp", 3.0 );
+        this.log( "Experience Merge Radius: " + this.expMerge );
+    }
 }