From ba76e746a2f772ee3d4be97af8995f2a0328c3b9 Mon Sep 17 00:00:00 2001
From: Konstantin Shandurenko <k.shandurenko@tinkoff.ru>
Date: Sun, 17 Oct 2021 22:07:59 +0300
Subject: [PATCH] Entity#lookAt and updating view in melee/ranged/combined
 attack goals when within attackable range (#494)

---
 .../net/minestom/server/entity/Entity.java    | 24 +++++++++++++++++++
 .../entity/ai/goal/CombinedAttackGoal.java    |  1 +
 .../entity/ai/goal/FollowTargetGoal.java      |  3 +--
 .../entity/ai/goal/MeleeAttackGoal.java       |  1 +
 .../entity/ai/goal/RangedAttackGoal.java      |  1 +
 5 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/main/java/net/minestom/server/entity/Entity.java b/src/main/java/net/minestom/server/entity/Entity.java
index 222001be6..006883b79 100644
--- a/src/main/java/net/minestom/server/entity/Entity.java
+++ b/src/main/java/net/minestom/server/entity/Entity.java
@@ -40,6 +40,7 @@ import net.minestom.server.utils.block.BlockIterator;
 import net.minestom.server.utils.chunk.ChunkUtils;
 import net.minestom.server.utils.entity.EntityUtils;
 import net.minestom.server.utils.player.PlayerUtils;
+import net.minestom.server.utils.position.PositionUtils;
 import net.minestom.server.utils.time.Cooldown;
 import net.minestom.server.utils.time.TimeUnit;
 import net.minestom.server.utils.validate.Check;
@@ -280,6 +281,29 @@ public class Entity implements Viewable, Tickable, TagHandler, PermissionHandler
         sendPacketToViewersAndSelf(new EntityRotationPacket(getEntityId(), yaw, pitch, onGround));
     }
 
+    /**
+     * Changes the view of the entity so that it looks in a direction to the given position.
+     *
+     * @param position the position to look at.
+     */
+    public void lookAt(@NotNull Pos position) {
+        Vec delta = position.sub(getPosition()).asVec().normalize();
+        setView(
+                PositionUtils.getLookYaw(delta.x(), delta.z()),
+                PositionUtils.getLookPitch(delta.x(), delta.y(), delta.z())
+        );
+    }
+
+    /**
+     * Changes the view of the entity so that it looks in a direction to the given entity.
+     *
+     * @param entity the entity to look at.
+     */
+    public void lookAt(@NotNull Entity entity) {
+        Check.argCondition(entity.instance != instance, "Entity can look at another entity that is within it's own instance");
+        lookAt(entity.position);
+    }
+
     /**
      * When set to true, the entity will automatically get new viewers when they come too close.
      * This can be use to have complete control over which player can see it, without having to deal with
diff --git a/src/main/java/net/minestom/server/entity/ai/goal/CombinedAttackGoal.java b/src/main/java/net/minestom/server/entity/ai/goal/CombinedAttackGoal.java
index 5cfa0f406..5dff8b4ef 100644
--- a/src/main/java/net/minestom/server/entity/ai/goal/CombinedAttackGoal.java
+++ b/src/main/java/net/minestom/server/entity/ai/goal/CombinedAttackGoal.java
@@ -198,6 +198,7 @@ public class CombinedAttackGoal extends GoalSelector {
             if (pathPosition != null) {
                 navigator.setPathTo(null);
             }
+            this.entityCreature.lookAt(target);
             return;
         }
         // Otherwise going to the target.
diff --git a/src/main/java/net/minestom/server/entity/ai/goal/FollowTargetGoal.java b/src/main/java/net/minestom/server/entity/ai/goal/FollowTargetGoal.java
index 74b192b94..183b56c6e 100644
--- a/src/main/java/net/minestom/server/entity/ai/goal/FollowTargetGoal.java
+++ b/src/main/java/net/minestom/server/entity/ai/goal/FollowTargetGoal.java
@@ -60,8 +60,7 @@ public class FollowTargetGoal extends GoalSelector {
             navigator.setPathTo(null);
             return;
         }
-        if (navigator.getPathPosition() == null ||
-                (!navigator.getPathPosition().samePoint(lastTargetPos))) {
+        if (navigator.getPathPosition() == null || !navigator.getPathPosition().samePoint(lastTargetPos)) {
             navigator.setPathTo(lastTargetPos);
         } else {
             forceEnd = true;
diff --git a/src/main/java/net/minestom/server/entity/ai/goal/MeleeAttackGoal.java b/src/main/java/net/minestom/server/entity/ai/goal/MeleeAttackGoal.java
index 0527d4c6e..d96ae1c9b 100644
--- a/src/main/java/net/minestom/server/entity/ai/goal/MeleeAttackGoal.java
+++ b/src/main/java/net/minestom/server/entity/ai/goal/MeleeAttackGoal.java
@@ -81,6 +81,7 @@ public class MeleeAttackGoal extends GoalSelector {
 
             // Attack the target entity
             if (entityCreature.getDistance(target) <= range) {
+                entityCreature.lookAt(target);
                 if (!Cooldown.hasCooldown(time, lastHit, delay)) {
                     entityCreature.attack(target, true);
                     this.lastHit = time;
diff --git a/src/main/java/net/minestom/server/entity/ai/goal/RangedAttackGoal.java b/src/main/java/net/minestom/server/entity/ai/goal/RangedAttackGoal.java
index 17efa45e9..d9b5a02f5 100644
--- a/src/main/java/net/minestom/server/entity/ai/goal/RangedAttackGoal.java
+++ b/src/main/java/net/minestom/server/entity/ai/goal/RangedAttackGoal.java
@@ -124,6 +124,7 @@ public class RangedAttackGoal extends GoalSelector {
             if (pathPosition != null) {
                 navigator.setPathTo(null);
             }
+            this.entityCreature.lookAt(target);
             return;
         }
         final var targetPosition = target.getPosition();