Context steering for NPCs (#12915)

Content.Client/NPC/NPCSteeringComponent.cs

@@ -0,0 +1,14 @@
+namespace Content.Client.NPC;
+
+[RegisterComponent]
+public sealed class NPCSteeringComponent : Component
+{
+    /* Not hooked up to the server component as it's used for debugging only.
+     */
+
+    public Vector2 Direction;
+
+    public float[] DangerMap = Array.Empty<float>();
+    public float[] InterestMap = Array.Empty<float>();
+    public List<Vector2> DangerPoints = new();
+}

Content.Client/NPC/NPCSteeringSystem.cs

@@ -0,0 +1,120 @@
+using Content.Client.Physics.Controllers;
+using Content.Shared.Movement.Components;
+using Content.Shared.NPC;
+using Content.Shared.NPC.Events;
+using Robust.Client.Graphics;
+using Robust.Shared.Enums;
+
+namespace Content.Client.NPC;
+
+public sealed class NPCSteeringSystem : SharedNPCSteeringSystem
+{
+    [Dependency] private readonly IOverlayManager _overlay = default!;
+
+    public bool DebugEnabled
+    {
+        get => _debugEnabled;
+        set
+        {
+            if (_debugEnabled == value)
+                return;
+
+            _debugEnabled = value;
+
+            if (_debugEnabled)
+            {
+                _overlay.AddOverlay(new NPCSteeringOverlay(EntityManager));
+                RaiseNetworkEvent(new RequestNPCSteeringDebugEvent()
+                {
+                    Enabled = true
+                });
+            }
+            else
+            {
+                _overlay.RemoveOverlay<NPCSteeringOverlay>();
+                RaiseNetworkEvent(new RequestNPCSteeringDebugEvent()
+                {
+                    Enabled = false
+                });
+
+                foreach (var comp in EntityQuery<NPCSteeringComponent>(true))
+                {
+                    RemCompDeferred<NPCSteeringComponent>(comp.Owner);
+                }
+            }
+        }
+    }
+
+    private bool _debugEnabled;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeNetworkEvent<NPCSteeringDebugEvent>(OnDebugEvent);
+    }
+
+    private void OnDebugEvent(NPCSteeringDebugEvent ev)
+    {
+        if (!DebugEnabled)
+            return;
+
+        foreach (var data in ev.Data)
+        {
+            if (!Exists(data.EntityUid))
+                continue;
+
+            var comp = EnsureComp<NPCSteeringComponent>(data.EntityUid);
+            comp.Direction = data.Direction;
+            comp.DangerMap = data.Danger;
+            comp.InterestMap = data.Interest;
+            comp.DangerPoints = data.DangerPoints;
+        }
+    }
+}
+
+public sealed class NPCSteeringOverlay : Overlay
+{
+    public override OverlaySpace Space => OverlaySpace.WorldSpace;
+
+    private readonly IEntityManager _entManager;
+
+    public NPCSteeringOverlay(IEntityManager entManager)
+    {
+        _entManager = entManager;
+    }
+
+    protected override void Draw(in OverlayDrawArgs args)
+    {
+        foreach (var (comp, mover, xform) in _entManager.EntityQuery<NPCSteeringComponent, InputMoverComponent, TransformComponent>(true))
+        {
+            if (xform.MapID != args.MapId)
+            {
+                continue;
+            }
+
+            var (worldPos, worldRot) = xform.GetWorldPositionRotation();
+
+            if (!args.WorldAABB.Contains(worldPos))
+                continue;
+
+            args.WorldHandle.DrawCircle(worldPos, 1f, Color.Green, false);
+            var rotationOffset = _entManager.System<MoverController>().GetParentGridAngle(mover);
+
+            foreach (var point in comp.DangerPoints)
+            {
+                args.WorldHandle.DrawCircle(point, 0.1f, Color.Red.WithAlpha(0.6f));
+            }
+
+            for (var i = 0; i < SharedNPCSteeringSystem.InterestDirections; i++)
+            {
+                var danger = comp.DangerMap[i];
+                var interest = comp.InterestMap[i];
+                var angle = Angle.FromDegrees(i * (360 / SharedNPCSteeringSystem.InterestDirections));
+                args.WorldHandle.DrawLine(worldPos, worldPos + (rotationOffset + angle).RotateVec(new Vector2(interest, 0f)), Color.LimeGreen);
+                args.WorldHandle.DrawLine(worldPos, worldPos + (rotationOffset + angle).RotateVec(new Vector2(danger, 0f)), Color.Red);
+            }
+
+            args.WorldHandle.DrawLine(worldPos, worldPos + rotationOffset.RotateVec(comp.Direction), Color.Cyan);
+        }
+    }
+}

Content.Server/NPC/Components/NPCSteeringComponent.cs

@@ -1,6 +1,6 @@
 using System.Threading;
-using Content.Server.CPUJob.JobQueues;
 using Content.Server.NPC.Pathfinding;
+using Content.Shared.NPC;
 using Robust.Shared.Map;
 
 namespace Content.Server.NPC.Components;
@@ -11,6 +11,43 @@ namespace Content.Server.NPC.Components;
 [RegisterComponent]
 public sealed class NPCSteeringComponent : Component
 {
+    #region Context Steering
+
+    /// <summary>
+    /// Used to override seeking behavior for context steering.
+    /// </summary>
+    [ViewVariables]
+    public bool CanSeek = true;
+
+    /// <summary>
+    /// Radius for collision avoidance.
+    /// </summary>
+    [ViewVariables(VVAccess.ReadWrite)]
+    public float Radius = 0.35f;
+
+    [ViewVariables]
+    public readonly float[] Interest = new float[SharedNPCSteeringSystem.InterestDirections];
+
+    [ViewVariables]
+    public readonly float[] Danger = new float[SharedNPCSteeringSystem.InterestDirections];
+
+    // TODO: Update radius, also danger points debug only
+    public readonly List<Vector2> DangerPoints = new();
+
+    #endregion
+
+    /// <summary>
+    /// How many times per second we're allowed to update our steering frequency.
+    /// </summary>
+    public const byte SteerFrequency = 10;
+
+    /// <summary>
+    /// Last time the NPC steered.
+    /// </summary>
+    public TimeSpan LastTimeSteer;
+
+    public Vector2 LastSteer;
+
     /// <summary>
     /// Have we currently requested a path.
     /// </summary>

Content.Server/NPC/Events/NPCSteeringEvent.cs

@@ -0,0 +1,24 @@
+using Content.Server.NPC.Components;
+
+namespace Content.Server.NPC.Events;
+
+/// <summary>
+/// Raised directed on an NPC when steering.
+/// </summary>
+[ByRefEvent]
+public readonly record struct NPCSteeringEvent(
+    NPCSteeringComponent Steering,
+    float[] Interest,
+    float[] Danger,
+    float AgentRadius,
+    Angle OffsetRotation,
+    Vector2 WorldPosition)
+{
+    public readonly NPCSteeringComponent Steering = Steering;
+    public readonly float[] Interest = Interest;
+    public readonly float[] Danger = Danger;
+
+    public readonly float AgentRadius = AgentRadius;
+    public readonly Angle OffsetRotation = OffsetRotation;
+    public readonly Vector2 WorldPosition = WorldPosition;
+}

Content.Server/NPC/HTN/PrimitiveTasks/Operators/NPCCombatOperator.cs

@@ -92,7 +92,8 @@ public abstract class NPCCombatOperator : HTNOperator
         {
             if (mobQuery.TryGetComponent(target, out var mobState) &&
                 mobState.CurrentState > DamageState.Alive ||
-                target == existingTarget)
+                target == existingTarget ||
+                target == owner)
             {
                 continue;
             }

Content.Server/NPC/Pathfinding/PathfindingSystem.cs

@@ -60,7 +60,7 @@ namespace Content.Server.NPC.Pathfinding
         private const int PathTickLimit = 256;
 
         private int _portalIndex;
-        private Dictionary<int, PathPortal> _portals = new();
+        private readonly Dictionary<int, PathPortal> _portals = new();
 
         public override void Initialize()
         {
@@ -317,6 +317,21 @@ namespace Content.Server.NPC.Pathfinding
             return await GetPath(request);
         }
 
+        /// <summary>
+        /// Gets a path in a thread-safe way.
+        /// </summary>
+        public async Task<PathResultEvent> GetPathSafe(
+            EntityUid entity,
+            EntityCoordinates start,
+            EntityCoordinates end,
+            float range,
+            CancellationToken cancelToken,
+            PathFlags flags = PathFlags.None)
+        {
+            var request = GetRequest(entity, start, end, range, cancelToken, flags);
+            return await GetPath(request, true);
+        }
+
         /// <summary>
         /// Asynchronously gets a path.
         /// </summary>
@@ -428,12 +443,22 @@ namespace Content.Server.NPC.Pathfinding
         }
 
         private async Task<PathResultEvent> GetPath(
-            PathRequest request)
+            PathRequest request, bool safe = false)
         {
             // We could maybe try an initial quick run to avoid forcing time-slicing over ticks.
             // For now it seems okay and it shouldn't block on 1 NPC anyway.
 
+            if (safe)
+            {
+                lock (_pathRequests)
+                {
                     _pathRequests.Add(request);
+                }
+            }
+            else
+            {
+                _pathRequests.Add(request);
+            }
 
             await request.Task;
 

Content.Server/NPC/Systems/FactionSystem.cs

@@ -139,6 +139,14 @@ namespace Content.Server.NPC.Systems
             }
         }
 
+        public bool IsFriendly(EntityUid uidA, EntityUid uidB, FactionComponent? factionA = null, FactionComponent? factionB = null)
+        {
+            if (!Resolve(uidA, ref factionA, false) || !Resolve(uidB, ref factionB, false))
+                return false;
+
+            return factionA.Factions.Overlaps(factionB.Factions) || factionA.FriendlyFactions.Overlaps(factionB.Factions);
+        }
+
         /// <summary>
         /// Makes the source faction friendly to the target faction, 1-way.
         /// </summary>

Content.Server/NPC/Systems/NPCCombatSystem.Melee.cs

@@ -1,7 +1,7 @@
 using Content.Server.CombatMode;
 using Content.Server.NPC.Components;
-using Content.Shared.MobState;
-using Content.Shared.MobState.Components;
+using Content.Server.NPC.Events;
+using Content.Shared.NPC;
 using Content.Shared.Weapons.Melee;
 using Robust.Shared.Map;
 using Robust.Shared.Physics.Components;
@@ -17,6 +17,52 @@ public sealed partial class NPCCombatSystem
     {
         SubscribeLocalEvent<NPCMeleeCombatComponent, ComponentStartup>(OnMeleeStartup);
         SubscribeLocalEvent<NPCMeleeCombatComponent, ComponentShutdown>(OnMeleeShutdown);
+        SubscribeLocalEvent<NPCMeleeCombatComponent, NPCSteeringEvent>(OnMeleeSteering);
+    }
+
+    private void OnMeleeSteering(EntityUid uid, NPCMeleeCombatComponent component, ref NPCSteeringEvent args)
+    {
+        args.Steering.CanSeek = true;
+
+        if (TryComp<MeleeWeaponComponent>(component.Weapon, out var weapon))
+        {
+            var cdRemaining = weapon.NextAttack - _timing.CurTime;
+
+            // If CD remaining then backup.
+            if (cdRemaining < TimeSpan.FromSeconds(1f / weapon.AttackRate) * 0.5f)
+                return;
+
+            if (!_physics.TryGetNearestPoints(uid, component.Target, out _, out var pointB))
+                return;
+
+            var idealDistance = weapon.Range * 1.25f;
+            var obstacleDirection = pointB - args.WorldPosition;
+            var obstacleDistance = obstacleDirection.Length;
+
+            if (obstacleDistance > idealDistance)
+            {
+                // Don't want to get too far.
+                return;
+            }
+
+            args.Steering.CanSeek = false;
+            obstacleDirection = args.OffsetRotation.RotateVec(obstacleDirection);
+            var norm = obstacleDirection.Normalized;
+
+            var weight = (obstacleDistance <= args.AgentRadius
+                ? 1f
+                : (idealDistance - obstacleDistance) / idealDistance);
+
+            for (var i = 0; i < SharedNPCSteeringSystem.InterestDirections; i++)
+            {
+                var result = -Vector2.Dot(norm, NPCSteeringSystem.Directions[i]) * weight;
+
+                if (result < 0f)
+                    continue;
+
+                args.Interest[i] = MathF.Max(args.Interest[i], result);
+            }
+        }
     }
 
     private void OnMeleeShutdown(EntityUid uid, NPCMeleeCombatComponent component, ComponentShutdown args)
@@ -107,7 +153,7 @@ public sealed partial class NPCCombatSystem
         // Gets unregistered on component shutdown.
         _steering.TryRegister(component.Owner, new EntityCoordinates(component.Target, Vector2.Zero), steering);
 
-        if (weapon.NextAttack > curTime)
+        if (weapon.NextAttack > curTime || !Enabled)
             return;
 
         if (_random.Prob(component.MissChance) &&

Content.Server/NPC/Systems/NPCCombatSystem.Ranged.cs

@@ -140,7 +140,7 @@ public sealed partial class NPCCombatSystem
 
             // TODO: Check if we can face
 
-            if (!_gun.CanShoot(gun))
+            if (!Enabled || !_gun.CanShoot(gun))
                 continue;
 
             EntityCoordinates targetCordinates;

Content.Server/NPC/Systems/NPCCombatSystem.cs

@@ -2,6 +2,7 @@ using Content.Server.Interaction;
 using Content.Server.Weapons.Ranged.Systems;
 using Content.Shared.Weapons.Melee;
 using Robust.Shared.Map;
+using Robust.Shared.Physics.Systems;
 using Robust.Shared.Random;
 using Robust.Shared.Timing;
 
@@ -20,8 +21,14 @@ public sealed partial class NPCCombatSystem : EntitySystem
     [Dependency] private readonly SharedAudioSystem _audio = default!;
     [Dependency] private readonly NPCSteeringSystem _steering = default!;
     [Dependency] private readonly SharedMeleeWeaponSystem _melee = default!;
+    [Dependency] private readonly SharedPhysicsSystem _physics = default!;
     [Dependency] private readonly SharedTransformSystem _transform = default!;
 
+    /// <summary>
+    /// If disabled we'll move into range but not attack.
+    /// </summary>
+    public bool Enabled = true;
+
     public override void Initialize()
     {
         base.Initialize();

Content.Server/NPC/Systems/NPCSteeringSystem.Context.cs

@@ -0,0 +1,425 @@
+using System.Linq;
+using Content.Server.NPC.Components;
+using Content.Server.NPC.Pathfinding;
+using Content.Shared.Interaction;
+using Content.Shared.Movement.Components;
+using Content.Shared.NPC;
+using Robust.Shared.Map;
+using Robust.Shared.Physics.Components;
+
+namespace Content.Server.NPC.Systems;
+
+public sealed partial class NPCSteeringSystem
+{
+    private void ApplySeek(float[] interest, Vector2 direction, float weight)
+    {
+        if (weight == 0f || direction == Vector2.Zero)
+            return;
+
+        var directionAngle = (float) direction.ToAngle().Theta;
+
+        for (var i = 0; i < InterestDirections; i++)
+        {
+            if (interest[i].Equals(-1f))
+                continue;
+
+            var angle = i * InterestRadians;
+            var dot = MathF.Cos(directionAngle - angle);
+            dot = (dot + 1) * 0.5f;
+            interest[i] += dot * weight;
+        }
+    }
+
+    #region Seek
+
+    /// <summary>
+    /// Attempts to head to the target destination, either via the next pathfinding node or the final target.
+    /// </summary>
+    private bool TrySeek(
+        EntityUid uid,
+        InputMoverComponent mover,
+        NPCSteeringComponent steering,
+        PhysicsComponent body,
+        TransformComponent xform,
+        Angle offsetRot,
+        float moveSpeed,
+        float[] interest,
+        EntityQuery<PhysicsComponent> bodyQuery,
+        float frameTime)
+    {
+        var ourCoordinates = xform.Coordinates;
+        var destinationCoordinates = steering.Coordinates;
+
+        // We've arrived, nothing else matters.
+        if (xform.Coordinates.TryDistance(EntityManager, destinationCoordinates, out var distance) &&
+            distance <= steering.Range)
+        {
+            steering.Status = SteeringStatus.InRange;
+            return true;
+        }
+
+        // Grab the target position, either the next path node or our end goal..
+        var targetCoordinates = GetTargetCoordinates(steering);
+        var needsPath = false;
+
+        // If the next node is invalid then get new ones
+        if (!targetCoordinates.IsValid(EntityManager))
+        {
+            if (steering.CurrentPath.TryPeek(out var poly) &&
+                (poly.Data.Flags & PathfindingBreadcrumbFlag.Invalid) != 0x0)
+            {
+                steering.CurrentPath.Dequeue();
+                // Try to get the next node temporarily.
+                targetCoordinates = GetTargetCoordinates(steering);
+                needsPath = true;
+            }
+        }
+
+        // Need to be pretty close if it's just a node to make sure LOS for door bashes or the likes.
+        float arrivalDistance;
+
+        if (targetCoordinates.Equals(steering.Coordinates))
+        {
+            // What's our tolerance for arrival.
+            // If it's a pathfinding node it might be different to the destination.
+            arrivalDistance = steering.Range;
+        }
+        else
+        {
+            arrivalDistance = SharedInteractionSystem.InteractionRange - 0.8f;
+        }
+
+        // Check if mapids match.
+        var targetMap = targetCoordinates.ToMap(EntityManager);
+        var ourMap = ourCoordinates.ToMap(EntityManager);
+
+        if (targetMap.MapId != ourMap.MapId)
+        {
+            steering.Status = SteeringStatus.NoPath;
+            return false;
+        }
+
+        var direction = targetMap.Position - ourMap.Position;
+
+        // Are we in range
+        if (direction.Length <= arrivalDistance)
+        {
+            // Node needs some kind of special handling like access or smashing.
+            if (steering.CurrentPath.TryPeek(out var node))
+            {
+                var status = TryHandleFlags(steering, node, bodyQuery);
+
+                // TODO: Need to handle re-pathing in case the target moves around.
+                switch (status)
+                {
+                    case SteeringObstacleStatus.Completed:
+                        break;
+                    case SteeringObstacleStatus.Failed:
+                        // TODO: Blacklist the poly for next query
+                        steering.Status = SteeringStatus.NoPath;
+                        return false;
+                    case SteeringObstacleStatus.Continuing:
+                        CheckPath(steering, xform, needsPath, distance);
+                        return true;
+                    default:
+                        throw new ArgumentOutOfRangeException();
+                }
+            }
+
+            // Otherwise it's probably regular pathing so just keep going a bit more to get to tile centre
+            if (direction.Length <= TileTolerance)
+            {
+                // It was just a node, not the target, so grab the next destination (either the target or next node).
+                if (steering.CurrentPath.Count > 0)
+                {
+                    steering.CurrentPath.Dequeue();
+
+                    // Alright just adjust slightly and grab the next node so we don't stop moving for a tick.
+                    // TODO: If it's the last node just grab the target instead.
+                    targetCoordinates = GetTargetCoordinates(steering);
+                    targetMap = targetCoordinates.ToMap(EntityManager);
+
+                    // Can't make it again.
+                    if (ourMap.MapId != targetMap.MapId)
+                    {
+                        SetDirection(mover, steering, Vector2.Zero);
+                        steering.Status = SteeringStatus.NoPath;
+                        return false;
+                    }
+
+                    // Gonna resume now business as usual
+                    direction = targetMap.Position - ourMap.Position;
+                }
+                else
+                {
+                    // This probably shouldn't happen as we check above but eh.
+                    steering.Status = SteeringStatus.NoPath;
+                    return false;
+                }
+            }
+        }
+
+        // Do we have no more nodes to follow OR has the target moved sufficiently? If so then re-path.
+        if (!needsPath)
+        {
+            needsPath = steering.CurrentPath.Count == 0 || (steering.CurrentPath.Peek().Data.Flags & PathfindingBreadcrumbFlag.Invalid) != 0x0;
+        }
+
+        // TODO: Probably need partial planning support i.e. patch from the last node to where the target moved to.
+        CheckPath(steering, xform, needsPath, distance);
+
+        // If we don't have a path yet then do nothing; this is to avoid stutter-stepping if it turns out there's no path
+        // available but we assume there was.
+        if (steering is { Pathfind: true, CurrentPath.Count: 0 })
+            return true;
+
+        if (moveSpeed == 0f || direction == Vector2.Zero)
+        {
+            steering.Status = SteeringStatus.NoPath;
+            return false;
+        }
+
+        var input = direction.Normalized;
+        var tickMovement = moveSpeed * frameTime;
+
+        // We have the input in world terms but need to convert it back to what movercontroller is doing.
+        input = offsetRot.RotateVec(input);
+        var norm = input.Normalized;
+        var weight = MapValue(direction.Length, tickMovement * 0.5f, tickMovement * 0.75f);
+
+        ApplySeek(interest, norm, weight);
+
+        // Prefer our current direction
+        if (weight > 0f && body.LinearVelocity.LengthSquared > 0f)
+        {
+            const float SameDirectionWeight = 0.1f;
+            norm = body.LinearVelocity.Normalized;
+
+            ApplySeek(interest, norm, SameDirectionWeight);
+        }
+
+        return true;
+    }
+
+
+    private void CheckPath(NPCSteeringComponent steering, TransformComponent xform, bool needsPath, float targetDistance)
+    {
+        if (!_pathfinding)
+        {
+            steering.CurrentPath.Clear();
+            steering.PathfindToken?.Cancel();
+            steering.PathfindToken = null;
+            return;
+        }
+
+        if (!needsPath)
+        {
+            // If the target has sufficiently moved.
+            var lastNode = GetCoordinates(steering.CurrentPath.Last());
+
+            if (lastNode.TryDistance(EntityManager, steering.Coordinates, out var lastDistance) &&
+                lastDistance > steering.RepathRange)
+            {
+                needsPath = true;
+            }
+        }
+
+        // Request the new path.
+        if (needsPath)
+        {
+            RequestPath(steering, xform, targetDistance);
+        }
+    }
+
+    /// <summary>
+    /// We may be pathfinding and moving at the same time in which case early nodes may be out of date.
+    /// </summary>
+    public void PrunePath(MapCoordinates mapCoordinates, Vector2 direction, Queue<PathPoly> nodes)
+    {
+        if (nodes.Count == 0)
+            return;
+
+        // Prune the first node as it's irrelevant.
+        nodes.Dequeue();
+
+        while (nodes.TryPeek(out var node))
+        {
+            if (!node.Data.IsFreeSpace)
+                break;
+
+            var nodeMap = node.Coordinates.ToMap(EntityManager);
+
+            // If any nodes are 'behind us' relative to the target we'll prune them.
+            // This isn't perfect but should fix most cases of stutter stepping.
+            if (nodeMap.MapId == mapCoordinates.MapId &&
+                Vector2.Dot(direction, nodeMap.Position - mapCoordinates.Position) < 0f)
+            {
+                nodes.Dequeue();
+                continue;
+            }
+
+            break;
+        }
+    }
+
+    /// <summary>
+    /// Get the coordinates we should be heading towards.
+    /// </summary>
+    private EntityCoordinates GetTargetCoordinates(NPCSteeringComponent steering)
+    {
+        // Depending on what's going on we may return the target or a pathfind node.
+
+        // Even if we're at the last node may not be able to head to target in case we get stuck on a corner or the likes.
+        if (_pathfinding && steering.CurrentPath.Count >= 1 && steering.CurrentPath.TryPeek(out var nextTarget))
+        {
+            return GetCoordinates(nextTarget);
+        }
+
+        return steering.Coordinates;
+    }
+
+    /// <summary>
+    /// Gets the fraction this value is between min and max
+    /// </summary>
+    /// <returns></returns>
+    private float MapValue(float value, float minValue, float maxValue)
+    {
+        if (maxValue > minValue)
+        {
+            var mapped = (value - minValue) / (maxValue - minValue);
+            return Math.Clamp(mapped, 0f, 1f);
+        }
+
+        return value >= minValue ? 1f : 0f;
+    }
+
+    #endregion
+
+    #region Static Avoidance
+
+    /// <summary>
+    /// Tries to avoid static blockers such as walls.
+    /// </summary>
+    private void CollisionAvoidance(
+        EntityUid uid,
+        Angle offsetRot,
+        Vector2 worldPos,
+        float agentRadius,
+        float moveSpeed,
+        PhysicsComponent body,
+        TransformComponent xform,
+        float[] danger,
+        List<Vector2> dangerPoints,
+        EntityQuery<PhysicsComponent> bodyQuery,
+        EntityQuery<TransformComponent> xformQuery)
+    {
+        var detectionRadius = agentRadius + moveSpeed;
+
+        foreach (var ent in _lookup.GetEntitiesInRange(uid, detectionRadius, LookupFlags.Static))
+        {
+            // TODO: If we can access the door or smth.
+            if (ent == uid ||
+                !bodyQuery.TryGetComponent(ent, out var otherBody) ||
+                !otherBody.Hard ||
+                !otherBody.CanCollide ||
+                ((body.CollisionMask & otherBody.CollisionLayer) == 0x0 &&
+                (body.CollisionLayer & otherBody.CollisionMask) == 0x0))
+            {
+                continue;
+            }
+
+            if (!_physics.TryGetNearestPoints(uid, ent, out var pointA, out var pointB, xform, xformQuery.GetComponent(ent)))
+                continue;
+
+            var obstacleDirection = (pointB - worldPos);
+            var obstableDistance = obstacleDirection.Length;
+
+            if (obstableDistance > detectionRadius)
+                continue;
+
+            dangerPoints.Add(pointB);
+            obstacleDirection = offsetRot.RotateVec(obstacleDirection);
+            var norm = obstacleDirection.Normalized;
+            var weight = obstableDistance <= agentRadius ? 1f : (detectionRadius - obstableDistance) / detectionRadius;
+
+            for (var i = 0; i < InterestDirections; i++)
+            {
+                var dot = Vector2.Dot(norm, Directions[i]);
+                danger[i] = MathF.Max(dot * weight, danger[i]);
+            }
+        }
+
+    }
+
+    #endregion
+
+    #region Dynamic Avoidance
+
+    /// <summary>
+    /// Tries to avoid mobs of the same faction.
+    /// </summary>
+    private void Separation(
+        EntityUid uid,
+        Angle offsetRot,
+        Vector2 worldPos,
+        float agentRadius,
+        PhysicsComponent body,
+        TransformComponent xform,
+        float[] interest,
+        float[] danger,
+        EntityQuery<PhysicsComponent> bodyQuery,
+        EntityQuery<TransformComponent> xformQuery)
+    {
+        var detectionRadius = agentRadius + 0.1f;
+        var ourVelocity = body.LinearVelocity;
+        var factionQuery = GetEntityQuery<FactionComponent>();
+        factionQuery.TryGetComponent(uid, out var ourFaction);
+
+        foreach (var ent in _lookup.GetEntitiesInRange(uid, detectionRadius, LookupFlags.Dynamic))
+        {
+            // TODO: If we can access the door or smth.
+            if (ent == uid ||
+                !bodyQuery.TryGetComponent(ent, out var otherBody) ||
+                !otherBody.Hard ||
+                !otherBody.CanCollide ||
+                (body.CollisionMask & otherBody.CollisionLayer) == 0x0 &&
+                (body.CollisionLayer & otherBody.CollisionMask) == 0x0 ||
+                !factionQuery.TryGetComponent(ent, out var otherFaction) ||
+                !_faction.IsFriendly(uid, ent, ourFaction, otherFaction) ||
+                Vector2.Dot(otherBody.LinearVelocity, ourVelocity) < 0f)
+            {
+                continue;
+            }
+
+            var xformB = xformQuery.GetComponent(ent);
+
+            if (!_physics.TryGetNearestPoints(uid, ent, out var pointA, out var pointB, xform, xformB))
+            {
+                continue;
+            }
+
+            var obstacleDirection = (pointB - worldPos);
+            var obstableDistance = obstacleDirection.Length;
+
+            if (obstableDistance > detectionRadius)
+                continue;
+
+            obstacleDirection = offsetRot.RotateVec(obstacleDirection);
+            var norm = obstacleDirection.Normalized;
+            var weight = obstableDistance <= agentRadius ? 1f : (detectionRadius - obstableDistance) / detectionRadius;
+            weight *= 1.5f;
+
+            for (var i = 0; i < InterestDirections; i++)
+            {
+                var dot = Vector2.Dot(norm, Directions[i]);
+                danger[i] = MathF.Max(dot * weight, danger[i]);
+            }
+        }
+    }
+
+    #endregion
+
+    // TODO: Alignment
+
+    // TODO: Cohesion
+}

Content.Server/NPC/Systems/NPCSteeringSystem.cs

@@ -1,31 +1,54 @@
 using System.Linq;
 using System.Threading;
+using System.Threading.Tasks;
+using Content.Server.Administration.Managers;
 using Content.Server.Doors.Systems;
 using Content.Server.NPC.Components;
+using Content.Server.NPC.Events;
 using Content.Server.NPC.Pathfinding;
 using Content.Shared.CCVar;
 using Content.Shared.Interaction;
 using Content.Shared.Movement.Components;
 using Content.Shared.Movement.Systems;
 using Content.Shared.NPC;
+using Content.Shared.NPC.Events;
 using Content.Shared.Weapons.Melee;
+using Robust.Server.Player;
 using Robust.Shared.Configuration;
 using Robust.Shared.Map;
 using Robust.Shared.Physics.Components;
 using Robust.Shared.Physics.Systems;
+using Robust.Shared.Player;
+using Robust.Shared.Players;
 using Robust.Shared.Random;
+using Robust.Shared.Threading;
 using Robust.Shared.Timing;
+using Robust.Shared.Utility;
 
 namespace Content.Server.NPC.Systems
 {
-    public sealed partial class NPCSteeringSystem : EntitySystem
+    public sealed partial class NPCSteeringSystem : SharedNPCSteeringSystem
     {
-        // http://www.red3d.com/cwr/papers/1999/gdc99steer.html for a steering overview
+        /*
+         * We use context steering to determine which way to move.
+         * This involves creating an array of possible directions and assigning a value for the desireability of each direction.
+         *
+         * There's multiple ways to implement this, e.g. you can average all directions, or you can choose the highest direction
+         * , or you can remove the danger map entirely and only having an interest map (AKA game endeavour).
+         * See http://www.gameaipro.com/GameAIPro2/GameAIPro2_Chapter18_Context_Steering_Behavior-Driven_Steering_at_the_Macro_Scale.pdf
+         * (though in their case it was for an F1 game so used context steering across the width of the road).
+         */
+
+        [Dependency] private readonly IAdminManager _admin = default!;
         [Dependency] private readonly IConfigurationManager _configManager = default!;
         [Dependency] private readonly IGameTiming _timing = default!;
         [Dependency] private readonly IMapManager _mapManager = default!;
+        [Dependency] private readonly IParallelManager _parallel = default!;
         [Dependency] private readonly IRobustRandom _random = default!;
         [Dependency] private readonly DoorSystem _doors = default!;
+        [Dependency] private readonly EntityLookupSystem _lookup = default!;
+        [Dependency] private readonly FactionSystem _faction = default!;
+        // [Dependency] private readonly MetaDataSystem _metadata = default!;
         [Dependency] private readonly PathfindingSystem _pathfindingSystem = default!;
         [Dependency] private readonly SharedInteractionSystem _interaction = default!;
         [Dependency] private readonly SharedMeleeWeaponSystem _melee = default!;
@@ -37,19 +60,28 @@ namespace Content.Server.NPC.Systems
 
         private bool _enabled;
 
+        private bool _pathfinding = true;
+
+        public static readonly Vector2[] Directions = new Vector2[InterestDirections];
+
+        private readonly HashSet<ICommonSession> _subscribedSessions = new();
+
         public override void Initialize()
         {
             base.Initialize();
-            UpdatesBefore.Add(typeof(SharedPhysicsSystem));
-            InitializeAvoidance();
-            _configManager.OnValueChanged(CCVars.NPCEnabled, SetNPCEnabled, true);
 
-            SubscribeLocalEvent<NPCSteeringComponent, ComponentShutdown>(OnSteeringShutdown);
+            for (var i = 0; i < InterestDirections; i++)
+            {
+                Directions[i] = new Angle(InterestRadians * i).ToVec();
             }
 
-        private void OnSteeringShutdown(EntityUid uid, NPCSteeringComponent component, ComponentShutdown args)
-        {
-            component.PathfindToken?.Cancel();
+            UpdatesBefore.Add(typeof(SharedPhysicsSystem));
+            InitializeAvoidance();
+            _configManager.OnValueChanged(CCVars.NPCEnabled, SetNPCEnabled);
+            _configManager.OnValueChanged(CCVars.NPCPathfinding, SetNPCPathfinding);
+
+            SubscribeLocalEvent<NPCSteeringComponent, ComponentShutdown>(OnSteeringShutdown);
+            SubscribeNetworkEvent<RequestNPCSteeringDebugEvent>(OnDebugRequest);
         }
 
         private void SetNPCEnabled(bool obj)
@@ -65,6 +97,20 @@ namespace Content.Server.NPC.Systems
             _enabled = obj;
         }
 
+        private void SetNPCPathfinding(bool value)
+        {
+            _pathfinding = value;
+
+            if (!_pathfinding)
+            {
+                foreach (var comp in EntityQuery<NPCSteeringComponent>(true))
+                {
+                    comp.PathfindToken?.Cancel();
+                    comp.PathfindToken = null;
+                }
+            }
+        }
+
         public override void Shutdown()
         {
             base.Shutdown();
@@ -72,6 +118,22 @@ namespace Content.Server.NPC.Systems
             _configManager.UnsubValueChanged(CCVars.NPCEnabled, SetNPCEnabled);
         }
 
+        private void OnDebugRequest(RequestNPCSteeringDebugEvent msg, EntitySessionEventArgs args)
+        {
+            if (!_admin.IsAdmin((IPlayerSession) args.SenderSession))
+                return;
+
+            if (msg.Enabled)
+                _subscribedSessions.Add(args.SenderSession);
+            else
+                _subscribedSessions.Remove(args.SenderSession);
+        }
+
+        private void OnSteeringShutdown(EntityUid uid, NPCSteeringComponent component, ComponentShutdown args)
+        {
+            component.PathfindToken?.Cancel();
+        }
+
         /// <summary>
         /// Adds the AI to the steering system to move towards a specific target
         /// </summary>
@@ -137,15 +199,41 @@ namespace Content.Server.NPC.Systems
             // Not every mob has the modifier component so do it as a separate query.
             var bodyQuery = GetEntityQuery<PhysicsComponent>();
             var modifierQuery = GetEntityQuery<MovementSpeedModifierComponent>();
+            var xformQuery = GetEntityQuery<TransformComponent>();
 
             var npcs = EntityQuery<NPCSteeringComponent, ActiveNPCComponent, InputMoverComponent, TransformComponent>()
                 .ToArray();
-
-            // TODO: Do this in parallel.
-            // Main obstacle is requesting a new path needs to be done synchronously
-            foreach (var (steering, _, mover, xform) in npcs)
+            var options = new ParallelOptions()
             {
-                Steer(steering, mover, xform, modifierQuery, bodyQuery, frameTime);
+                MaxDegreeOfParallelism = _parallel.ParallelProcessCount,
+            };
+
+            Parallel.For(0, npcs.Length, options, i =>
+            {
+                var (steering, _, mover, xform) = npcs[i];
+
+                Steer(steering, mover, xform, modifierQuery, bodyQuery, xformQuery, frameTime);
+                steering.LastSteer = mover.CurTickSprintMovement;
+            });
+
+            if (_subscribedSessions.Count > 0)
+            {
+                var data = new List<NPCSteeringDebugData>(npcs.Length);
+
+                foreach (var (steering, _, mover, _) in npcs)
+                {
+                    data.Add(new NPCSteeringDebugData(
+                        mover.Owner,
+                        mover.CurTickSprintMovement,
+                        steering.Interest,
+                        steering.Danger,
+                        steering.DangerPoints));
+                }
+
+                var filter = Filter.Empty();
+                filter.AddPlayers(_subscribedSessions);
+
+                RaiseNetworkEvent(new NPCSteeringDebugEvent(data), filter);
             }
         }
 
@@ -170,6 +258,7 @@ namespace Content.Server.NPC.Systems
             TransformComponent xform,
             EntityQuery<MovementSpeedModifierComponent> modifierQuery,
             EntityQuery<PhysicsComponent> bodyQuery,
+            EntityQuery<TransformComponent> xformQuery,
             float frameTime)
         {
             if (Deleted(steering.Coordinates.EntityId))
@@ -179,242 +268,93 @@ namespace Content.Server.NPC.Systems
                 return;
             }
 
-            var ourCoordinates = xform.Coordinates;
-            var destinationCoordinates = steering.Coordinates;
-
-            // We've arrived, nothing else matters.
-            if (xform.Coordinates.TryDistance(EntityManager, destinationCoordinates, out var distance) &&
-                distance <= steering.Range)
+            // No path set from pathfinding or the likes.
+            if (steering.Status == SteeringStatus.NoPath)
             {
                 SetDirection(mover, steering, Vector2.Zero);
-                steering.Status = SteeringStatus.InRange;
                 return;
             }
 
             // Can't move at all, just noop input.
             if (!mover.CanMove)
-            {
-                SetDirection(mover, steering, Vector2.Zero);
-                steering.Status = SteeringStatus.Moving;
-                return;
-            }
-
-            // Grab the target position, either the next path node or our end goal.
-            // TODO: Some situations we may not want to move at our target without a path.
-            var targetCoordinates = GetTargetCoordinates(steering);
-            var needsPath = false;
-
-            // If the next node is invalid then get new ones
-            if (!targetCoordinates.IsValid(EntityManager))
-            {
-                if (steering.CurrentPath.TryPeek(out var poly) &&
-                    (poly.Data.Flags & PathfindingBreadcrumbFlag.Invalid) != 0x0)
-                {
-                    steering.CurrentPath.Dequeue();
-                    // Try to get the next node temporarily.
-                    targetCoordinates = GetTargetCoordinates(steering);
-                    needsPath = true;
-                }
-            }
-
-            // Need to be pretty close if it's just a node to make sure LOS for door bashes or the likes.
-            float arrivalDistance;
-
-            if (targetCoordinates.Equals(steering.Coordinates))
-            {
-                // What's our tolerance for arrival.
-                // If it's a pathfinding node it might be different to the destination.
-                arrivalDistance = steering.Range;
-            }
-            else
-            {
-                arrivalDistance = SharedInteractionSystem.InteractionRange - 0.8f;
-            }
-
-            // Check if mapids match.
-            var targetMap = targetCoordinates.ToMap(EntityManager);
-            var ourMap = ourCoordinates.ToMap(EntityManager);
-
-            if (targetMap.MapId != ourMap.MapId)
             {
                 SetDirection(mover, steering, Vector2.Zero);
                 steering.Status = SteeringStatus.NoPath;
                 return;
             }
 
-            var direction = targetMap.Position - ourMap.Position;
+            // TODO: Pause time
+            // Need it on the paused event which needs an engine PR.
+            var nextSteer = steering.LastTimeSteer + TimeSpan.FromSeconds(1f / NPCSteeringComponent.SteerFrequency);
 
-            // Are we in range
-            if (direction.Length <= arrivalDistance)
+            if (nextSteer > _timing.CurTime)
             {
-                // Node needs some kind of special handling like access or smashing.
-                if (steering.CurrentPath.TryPeek(out var node))
-                {
-                    var status = TryHandleFlags(steering, node, bodyQuery);
-
-                    // TODO: Need to handle re-pathing in case the target moves around.
-                    switch (status)
-                    {
-                        case SteeringObstacleStatus.Completed:
-                            break;
-                        case SteeringObstacleStatus.Failed:
-                            // TODO: Blacklist the poly for next query
-                            SetDirection(mover, steering, Vector2.Zero);
-                            steering.Status = SteeringStatus.NoPath;
-                            return;
-                        case SteeringObstacleStatus.Continuing:
-                            SetDirection(mover, steering, Vector2.Zero, false);
-                            CheckPath(steering, xform, needsPath, distance);
-                            return;
-                        default:
-                            throw new ArgumentOutOfRangeException();
-                    }
-                }
-
-                // Otherwise it's probably regular pathing so just keep going a bit more to get to tile centre
-                if (direction.Length <= TileTolerance)
-                {
-                    // It was just a node, not the target, so grab the next destination (either the target or next node).
-                    if (steering.CurrentPath.Count > 0)
-                    {
-                        steering.CurrentPath.Dequeue();
-
-                        // Alright just adjust slightly and grab the next node so we don't stop moving for a tick.
-                        // TODO: If it's the last node just grab the target instead.
-                        targetCoordinates = GetTargetCoordinates(steering);
-                        targetMap = targetCoordinates.ToMap(EntityManager);
-
-                        // Can't make it again.
-                        if (ourMap.MapId != targetMap.MapId)
-                        {
-                            SetDirection(mover, steering, Vector2.Zero);
-                            steering.Status = SteeringStatus.NoPath;
+                SetDirection(mover, steering, steering.LastSteer, false);
                 return;
             }
 
-                        // Gonna resume now business as usual
-                        direction = targetMap.Position - ourMap.Position;
-                    }
-                    else
-                    {
-                        // This probably shouldn't happen as we check above but eh.
-                        SetDirection(mover, steering, Vector2.Zero);
-                        steering.Status = SteeringStatus.InRange;
-                        return;
-                    }
-                }
-            }
+            steering.LastTimeSteer = _timing.CurTime;
+            var uid = mover.Owner;
+            var interest = steering.Interest;
+            var danger = steering.Danger;
+            var agentRadius = steering.Radius;
+            var worldPos = xform.WorldPosition;
 
-            // Do we have no more nodes to follow OR has the target moved sufficiently? If so then re-path.
-            if (!needsPath)
-            {
-                needsPath = steering.CurrentPath.Count == 0 || (steering.CurrentPath.Peek().Data.Flags & PathfindingBreadcrumbFlag.Invalid) != 0x0;
-            }
-
-            // TODO: Probably need partial planning support i.e. patch from the last node to where the target moved to.
-            CheckPath(steering, xform, needsPath, distance);
-
-            if (steering.Pathfind && steering.CurrentPath.Count == 0)
-            {
-                SetDirection(mover, steering, Vector2.Zero, false);
-                return;
-            }
-
-            modifierQuery.TryGetComponent(steering.Owner, out var modifier);
+            // Use rotation relative to parent to rotate our context vectors by.
+            var offsetRot = -_mover.GetParentGridAngle(mover);
+            modifierQuery.TryGetComponent(uid, out var modifier);
             var moveSpeed = GetSprintSpeed(steering.Owner, modifier);
+            var tickMove = moveSpeed * frameTime;
+            var body = bodyQuery.GetComponent(uid);
+            var dangerPoints = steering.DangerPoints;
+            dangerPoints.Clear();
 
-            var input = direction.Normalized;
+            for (var i = 0; i < InterestDirections; i++)
+            {
+                steering.Interest[i] = 0f;
+                steering.Danger[i] = 0f;
+            }
 
-            // If we're going to overshoot then... don't.
-            // TODO: For tile / movement we don't need to get bang on, just need to make sure we don't overshoot the far end.
-            var tickMovement = moveSpeed * frameTime;
+            var ev = new NPCSteeringEvent(steering, interest, danger, agentRadius, offsetRot, worldPos);
+            RaiseLocalEvent(uid, ref ev);
 
-            if (tickMovement.Equals(0f))
+            if (steering.CanSeek && !TrySeek(uid, mover, steering, body, xform, offsetRot, moveSpeed, interest, bodyQuery,  frameTime))
             {
                 SetDirection(mover, steering, Vector2.Zero);
-                steering.Status = SteeringStatus.NoPath;
                 return;
             }
+            DebugTools.Assert(!float.IsNaN(interest[0]));
 
-            // We may overshoot slightly but still be in the arrival distance which is okay.
-            var maxDistance = direction.Length + arrivalDistance;
+            // Avoid static objects like walls
+            CollisionAvoidance(uid, offsetRot, worldPos, agentRadius, tickMove, body, xform, danger, dangerPoints, bodyQuery, xformQuery);
+            DebugTools.Assert(!float.IsNaN(danger[0]));
 
-            if (tickMovement > maxDistance)
+            Separation(uid, offsetRot, worldPos, agentRadius, body, xform, interest, danger, bodyQuery, xformQuery);
+
+            // Remove the danger map from the interest map.
+            var desiredDirection = -1;
+            var desiredValue = 0f;
+
+            for (var i = 0; i < InterestDirections; i++)
             {
-                input *= maxDistance / tickMovement;
-            }
+                var adjustedValue = Math.Clamp(interest[i] - danger[i], 0f, 1f);
 
-            // We have the input in world terms but need to convert it back to what movercontroller is doing.
-            input = (-_mover.GetParentGridAngle(mover)).RotateVec(input);
-            SetDirection(mover, steering, input);
-        }
-
-        private void CheckPath(NPCSteeringComponent steering, TransformComponent xform, bool needsPath, float targetDistance)
+                if (adjustedValue > desiredValue)
                 {
-            if (!needsPath)
-            {
-                // If the target has sufficiently moved.
-                var lastNode = GetCoordinates(steering.CurrentPath.Last());
-
-                if (lastNode.TryDistance(EntityManager, steering.Coordinates, out var lastDistance) &&
-                    lastDistance > steering.RepathRange)
-                {
-                    needsPath = true;
+                    desiredDirection = i;
+                    desiredValue = adjustedValue;
                 }
             }
 
-            // Request the new path.
-            if (needsPath)
+            var resultDirection = Vector2.Zero;
+
+            if (desiredDirection != -1)
             {
-                RequestPath(steering, xform, targetDistance);
-            }
+                resultDirection = new Angle(desiredDirection * InterestRadians).ToVec();
             }
 
-        /// <summary>
-        /// We may be pathfinding and moving at the same time in which case early nodes may be out of date.
-        /// </summary>
-        public void PrunePath(MapCoordinates mapCoordinates, Vector2 direction, Queue<PathPoly> nodes)
-        {
-            if (nodes.Count == 0)
-                return;
-
-            // Prune the first node as it's irrelevant.
-            nodes.Dequeue();
-
-            while (nodes.TryPeek(out var node))
-            {
-                if (!node.Data.IsFreeSpace)
-                    break;
-
-                var nodeMap = node.Coordinates.ToMap(EntityManager);
-
-                // If any nodes are 'behind us' relative to the target we'll prune them.
-                // This isn't perfect but should fix most cases of stutter stepping.
-                if (nodeMap.MapId == mapCoordinates.MapId &&
-                    Vector2.Dot(direction, nodeMap.Position - mapCoordinates.Position) < 0f)
-                {
-                    nodes.Dequeue();
-                    continue;
-                }
-
-                break;
-            }
-        }
-
-        /// <summary>
-        /// Get the coordinates we should be heading towards.
-        /// </summary>
-        private EntityCoordinates GetTargetCoordinates(NPCSteeringComponent steering)
-        {
-            // Depending on what's going on we may return the target or a pathfind node.
-
-            // Even if we're at the last node may not be able to head to target in case we get stuck on a corner or the likes.
-            if (steering.CurrentPath.Count >= 1 && steering.CurrentPath.TryPeek(out var nextTarget))
-            {
-                return GetCoordinates(nextTarget);
-            }
-
-            return steering.Coordinates;
+            DebugTools.Assert(!float.IsNaN(resultDirection.X));
+            SetDirection(mover, steering, resultDirection, false);
         }
 
         private EntityCoordinates GetCoordinates(PathPoly poly)
@@ -435,11 +375,21 @@ namespace Content.Server.NPC.Systems
             if (steering.Pathfind || targetDistance < steering.RepathRange)
                 return;
 
+            // Short-circuit with no path.
+            var targetPoly = _pathfindingSystem.GetPoly(steering.Coordinates);
+
+            if (targetPoly != null && steering.Coordinates.Position.Equals(Vector2.Zero) && _interaction.InRangeUnobstructed(steering.Owner, steering.Coordinates.EntityId))
+            {
+                steering.CurrentPath.Clear();
+                steering.CurrentPath.Enqueue(targetPoly);
+                return;
+            }
+
             steering.PathfindToken = new CancellationTokenSource();
 
             var flags = _pathfindingSystem.GetFlags(steering.Owner);
 
-            var result = await _pathfindingSystem.GetPath(
+            var result = await _pathfindingSystem.GetPathSafe(
                 steering.Owner,
                 xform.Coordinates,
                 steering.Coordinates,

Content.Shared/CCVar/CCVars.cs

@@ -537,6 +537,11 @@ namespace Content.Shared.CCVar
 
         public static readonly CVarDef<bool> NPCEnabled = CVarDef.Create("npc.enabled", true);
 
+        /// <summary>
+        /// Should NPCs pathfind when steering. For debug purposes.
+        /// </summary>
+        public static readonly CVarDef<bool> NPCPathfinding = CVarDef.Create("npc.pathfinding", true);
+
         public static readonly CVarDef<bool> NPCCollisionAvoidance = CVarDef.Create("npc.collision_avoidance", true);
 
         /*

Content.Shared/NPC/Events/NPCSteeringDebugEvent.cs

@@ -0,0 +1,32 @@
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.NPC.Events;
+
+/// <summary>
+/// Client debug data for NPC steering
+/// </summary>
+[Serializable, NetSerializable]
+public sealed class NPCSteeringDebugEvent : EntityEventArgs
+{
+    public List<NPCSteeringDebugData> Data;
+
+    public NPCSteeringDebugEvent(List<NPCSteeringDebugData> data)
+    {
+        Data = data;
+    }
+}
+
+[Serializable, NetSerializable]
+public readonly record struct NPCSteeringDebugData(
+    EntityUid EntityUid,
+    Vector2 Direction,
+    float[] Interest,
+    float[] Danger,
+    List<Vector2> DangerPoints)
+{
+    public readonly EntityUid EntityUid = EntityUid;
+    public readonly Vector2 Direction = Direction;
+    public readonly float[] Interest = Interest;
+    public readonly float[] Danger = Danger;
+    public readonly List<Vector2> DangerPoints = DangerPoints;
+}

Content.Shared/NPC/Events/RequestNPCSteeringDebugEvent.cs

@@ -0,0 +1,12 @@
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.NPC.Events;
+
+/// <summary>
+/// Raised from client to server to request NPC steering debug info.
+/// </summary>
+[Serializable, NetSerializable]
+public sealed class RequestNPCSteeringDebugEvent : EntityEventArgs
+{
+    public bool Enabled;
+}

Content.Shared/NPC/PathfindingDebugMode.cs

@@ -23,24 +23,26 @@ public enum PathfindingDebugMode : ushort
     /// <summary>
     /// Shows all of the pathfinding polys.
     /// </summary>
-    Polys = 1 << 6,
+    Polys = 1 << 3,
 
     /// <summary>
     /// Shows the edges between pathfinding polys.
     /// </summary>
-    PolyNeighbors = 1 << 7,
+    PolyNeighbors = 1 << 4,
 
     /// <summary>
     /// Shows the nearest poly to the mouse cursor.
     /// </summary>
-    Poly = 1 << 8,
+    Poly = 1 << 5,
 
     /// <summary>
     /// Gets a path from the current attached entity to the mouse cursor.
     /// </summary>
-    Path = 1 << 9,
+    // Path = 1 << 6,
 
-    Routes = 1 << 10,
+    Routes = 1 << 6,
 
-    RouteCosts = 1 << 11,
+    RouteCosts = 1 << 7,
+
+    Steering = 1 << 8,
 }

Content.Shared/NPC/SharedNPCSteeringSystem.cs

@@ -0,0 +1,16 @@
+namespace Content.Shared.NPC;
+
+public abstract class SharedNPCSteeringSystem : EntitySystem
+{
+    public const byte InterestDirections = 12;
+
+    /// <summary>
+    /// How many radians between each interest direction.
+    /// </summary>
+    public const float InterestRadians = MathF.Tau / InterestDirections;
+
+    /// <summary>
+    /// How many degrees between each interest direction.
+    /// </summary>
+    public const float InterestDegrees = 360f / InterestDirections;
+}