From 4dcdc0e5027ab60a9c6c4a67d5fbb719a27af719 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Sat, 5 Mar 2022 12:45:57 -0800
Subject: [PATCH] Fix cancelling ProjectileHitEvent for piercing arrows (#7492)
---
build-data/paper.at | 3 ++
...rojectileHitEvent-for-piercing-arrow.patch | 37 +++++++++++++++++++
2 files changed, 40 insertions(+)
create mode 100644 patches/server/Fix-cancelling-ProjectileHitEvent-for-piercing-arrow.patch
diff --git a/build-data/paper.at b/build-data/paper.at
index c672e2bab1..1f7a551541 100644
--- a/build-data/paper.at
+++ b/build-data/paper.at
@@ -318,3 +318,6 @@ public-f net.minecraft.world.inventory.AbstractContainerMenu remoteDataSlots
# Fix falling block spawn methods
public net.minecraft.world.entity.item.FallingBlockEntity <init>(Lnet/minecraft/world/level/Level;DDDLnet/minecraft/world/level/block/state/BlockState;)V
+
+# Fix cancelling ProjectileHitEvent for piercing arrows
+protected net.minecraft.world.entity.projectile.Projectile hitCancelled
diff --git a/patches/server/Fix-cancelling-ProjectileHitEvent-for-piercing-arrow.patch b/patches/server/Fix-cancelling-ProjectileHitEvent-for-piercing-arrow.patch
new file mode 100644
index 0000000000..81a5ca02e6
--- /dev/null
+++ b/patches/server/Fix-cancelling-ProjectileHitEvent-for-piercing-arrow.patch
@@ -0,0 +1,37 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Jake Potrebic <jake.m.potrebic@gmail.com>
+Date: Sat, 19 Feb 2022 19:05:59 -0800
+Subject: [PATCH] Fix cancelling ProjectileHitEvent for piercing arrows
+
+Piercing arrows search for multiple entities inside a while
+loop that is checking the projectile entity's removed state.
+If the hit event is cancelled on the first entity, the event will
+be called over and over again inside that while loop until the event
+is not cancelled. The solution here, is to make use of an
+already-existing field on AbstractArrow for tracking entities hit by
+piercing arrows to avoid duplicate damage being applied.
+
+diff --git a/src/main/java/net/minecraft/world/entity/projectile/AbstractArrow.java b/src/main/java/net/minecraft/world/entity/projectile/AbstractArrow.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/world/entity/projectile/AbstractArrow.java
++++ b/src/main/java/net/minecraft/world/entity/projectile/AbstractArrow.java
+@@ -0,0 +0,0 @@ public abstract class AbstractArrow extends Projectile {
+ }
+ }
+
++ // Paper start
++ @Override
++ protected void preOnHit(HitResult hitResult) {
++ super.preOnHit(hitResult);
++ if (hitResult instanceof EntityHitResult entityHitResult && this.hitCancelled && this.getPierceLevel() > 0) {
++ if (this.piercingIgnoreEntityIds == null) {
++ this.piercingIgnoreEntityIds = new IntOpenHashSet(5);
++ }
++ this.piercingIgnoreEntityIds.add(entityHitResult.getEntity().getId());
++ }
++ }
++ // Paper end
++
+ private boolean shouldFall() {
+ return this.inGround && this.level.noCollision((new AABB(this.position(), this.position())).inflate(0.06D));
+ }