Add projectile hit simulation API (#8816)

This adds API to force a projectile to hit a provided entity. Example usage could be if you have a player disguised as another entity, you could simulate an arrow colliding with the (fake) entity hitbox.

patches/api/0371-More-Projectile-API.patch

@@ -178,10 +178,10 @@ index d1b37530319f6d37ee37f62080289c1e45848bc8..e94c7e279356c510f60508b26277d489
 +    // Paper end
  }
 diff --git a/src/main/java/org/bukkit/entity/Projectile.java b/src/main/java/org/bukkit/entity/Projectile.java
-index a523fca4baab447181ef91df67fa69b24e010149..6935f8806ca1ed87fa761e73bc0f6c41ab60453e 100644
+index a523fca4baab447181ef91df67fa69b24e010149..d97904540ff5cf103604862a5a1a3a41f56dfe33 100644
 --- a/src/main/java/org/bukkit/entity/Projectile.java
 +++ b/src/main/java/org/bukkit/entity/Projectile.java
-@@ -43,4 +43,45 @@ public interface Projectile extends Entity {
+@@ -43,4 +43,80 @@ public interface Projectile extends Entity {
       */
      @Deprecated(forRemoval = true) // Paper
      public void setBounce(boolean doesBounce);
@@ -225,6 +225,41 @@ index a523fca4baab447181ef91df67fa69b24e010149..6935f8806ca1ed87fa761e73bc0f6c41
 +     * @param beenShot has been in shot into the world
 +     */
 +    void setHasBeenShot(boolean beenShot);
++
++    /**
++     * Gets whether this projectile can hit an entity.
++     * <p>
++     * This method returns true under the following conditions:
++     * <p>
++     * - The shooter can see the entity ({@link Player#canSee(Entity)}) <p>
++     * - The entity is alive and not a spectator <p>
++     * - The projectile has left the hitbox of the shooter ({@link #hasLeftShooter()})<p>
++     * - If this is an arrow with piercing, it has not pierced the entity already
++     *
++     * @param entity the entity to check if this projectile can hit
++     * @return true if this projectile can damage the entity, false otherwise
++     */
++    boolean canHitEntity(@org.jetbrains.annotations.NotNull Entity entity);
++
++    /**
++     * Makes this projectile hit a specific entity.
++     * This uses the current position of the projectile for the hit point.
++     * Using this method will result in {@link org.bukkit.event.entity.ProjectileHitEvent} being called.
++     * @param entity the entity to hit
++     * @see #hitEntity(Entity, org.bukkit.util.Vector)
++     * @see #canHitEntity(Entity) 
++     */
++    void hitEntity(@org.jetbrains.annotations.NotNull Entity entity);
++
++    /**
++     * Makes this projectile hit a specific entity from a specific point.
++     * Using this method will result in {@link org.bukkit.event.entity.ProjectileHitEvent} being called.
++     * @param entity the entity to hit
++     * @param vector the direction to hit from
++     * @see #hitEntity(Entity)
++     * @see #canHitEntity(Entity) 
++     */
++    void hitEntity(@org.jetbrains.annotations.NotNull Entity entity, @org.jetbrains.annotations.NotNull org.bukkit.util.Vector vector);
 +    // Paper end
  }
 diff --git a/src/main/java/org/bukkit/entity/ShulkerBullet.java b/src/main/java/org/bukkit/entity/ShulkerBullet.java

patches/server/0812-Fix-cancelling-ProjectileHitEvent-for-piercing-arrow.patch

@@ -15,7 +15,7 @@ piercing arrows to avoid duplicate damage being applied.
 protected net.minecraft.world.entity.projectile.Projectile hitCancelled
 
 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 8c08e07ba78e2ed042d79b692221008f59e92593..9788e477ff1446ad2ea3669922cc7dfc09900ce8 100644
+index 740f08e5fadf9b8d277af05cc9734ceb54f54abb..09a4c0d30898bbdc05e32b6f1d4b0436a5e4af53 100644
 --- a/src/main/java/net/minecraft/world/entity/projectile/AbstractArrow.java
 +++ b/src/main/java/net/minecraft/world/entity/projectile/AbstractArrow.java
 @@ -290,6 +290,19 @@ public abstract class AbstractArrow extends Projectile {
@@ -24,7 +24,7 @@ index 8c08e07ba78e2ed042d79b692221008f59e92593..9788e477ff1446ad2ea3669922cc7dfc
  
 +    // Paper start
 +    @Override
-+    protected void preOnHit(HitResult hitResult) {
++    public void preOnHit(HitResult hitResult) {
 +        super.preOnHit(hitResult);
 +        if (hitResult instanceof EntityHitResult entityHitResult && this.hitCancelled && this.getPierceLevel() > 0) {
 +            if (this.piercingIgnoreEntityIds == null) {

patches/server/0813-More-Projectile-API.patch

@@ -14,6 +14,8 @@ public net.minecraft.world.entity.projectile.AbstractArrow soundEvent
 public net.minecraft.world.entity.projectile.ThrownTrident dealtDamage
 public net.minecraft.world.entity.projectile.Projectile hasBeenShot
 public net.minecraft.world.entity.projectile.Projectile leftOwner
+public net.minecraft.world.entity.projectile.Projectile preOnHit(Lnet/minecraft/world/phys/HitResult;)V
+public net.minecraft.world.entity.projectile.Projectile canHitEntity(Lnet/minecraft/world/entity/Entity;)Z
 
 Co-authored-by: Nassim Jahnke <nassim@njahnke.dev>
 
@@ -43,10 +45,10 @@ index 740ff3fed9c8d637527fda8544eba2b9d7d7280a..1f1519c1b33d16eba59546c86f20a099
              }
  
 diff --git a/src/main/java/org/bukkit/craftbukkit/entity/AbstractProjectile.java b/src/main/java/org/bukkit/craftbukkit/entity/AbstractProjectile.java
-index 40e5b19bc8fa3de3b3d54da0762aee5bd7bb8d7b..825fdc6162797ade8e76e1ca3a863ed5fb48f936 100644
+index 40e5b19bc8fa3de3b3d54da0762aee5bd7bb8d7b..1c8d63e462f3ed3d5286659ae0d1ec04d8b55177 100644
 --- a/src/main/java/org/bukkit/craftbukkit/entity/AbstractProjectile.java
 +++ b/src/main/java/org/bukkit/craftbukkit/entity/AbstractProjectile.java
-@@ -21,5 +21,31 @@ public abstract class AbstractProjectile extends CraftEntity implements Projecti
+@@ -21,5 +21,46 @@ public abstract class AbstractProjectile extends CraftEntity implements Projecti
      public void setBounce(boolean doesBounce) {
          this.doesBounce = doesBounce;
      }
@@ -72,6 +74,21 @@ index 40e5b19bc8fa3de3b3d54da0762aee5bd7bb8d7b..825fdc6162797ade8e76e1ca3a863ed5
 +    }
 +
 +    @Override
++    public boolean canHitEntity(org.bukkit.entity.Entity entity) {
++        return this.getHandle().canHitEntity(((CraftEntity) entity).getHandle());
++    }
++
++    @Override
++    public void hitEntity(org.bukkit.entity.Entity entity) {
++        this.getHandle().preOnHit(new net.minecraft.world.phys.EntityHitResult(((CraftEntity) entity).getHandle()));
++    }
++
++    @Override
++    public void hitEntity(org.bukkit.entity.Entity entity, org.bukkit.util.Vector vector) {
++        this.getHandle().preOnHit(new net.minecraft.world.phys.EntityHitResult(((CraftEntity) entity).getHandle(), new net.minecraft.world.phys.Vec3(vector.getX(), vector.getY(), vector.getZ())));
++    }
++
++    @Override
 +    public net.minecraft.world.entity.projectile.Projectile getHandle() {
 +        return (net.minecraft.world.entity.projectile.Projectile) entity;
 +    }