Fixes ghosts being affected by gravity.

Fixes #980

Content.Server/GameObjects/EntitySystems/MoverSystem.cs

@@ -5,6 +5,7 @@ using Content.Server.GameObjects.Components.Sound;
 using Content.Server.Interfaces.GameObjects.Components.Movement;
 using Content.Shared.Audio;
 using Content.Shared.GameObjects.Components.Inventory;
+using Content.Shared.GameObjects.Components.Movement;
 using Content.Shared.Maps;
 using Content.Shared.Physics;
 using JetBrains.Annotations;
@@ -151,7 +152,8 @@ namespace Content.Server.GameObjects.EntitySystems
                 physics.SetController<MoverController>();
             }
 
-            var weightless = _physicsManager.IsWeightless(transform.GridPosition);
+            var weightless = !transform.Owner.HasComponent<MovementIgnoreGravityComponent>() &&
+                             _physicsManager.IsWeightless(transform.GridPosition);
 
             if (weightless && collider != null)
             {

Content.Shared/GameObjects/Components/Movement/MovementIgnoreGravityComponent.cs

@@ -0,0 +1,10 @@
+using Robust.Shared.GameObjects;
+
+namespace Content.Shared.GameObjects.Components.Movement
+{
+    [RegisterComponent]
+    public sealed class MovementIgnoreGravityComponent : Component
+    {
+        public override string Name => "MovementIgnoreGravity";
+    }
+}

Content.Shared/Physics/MoverController.cs

@@ -1,4 +1,4 @@
-using System;
+using Content.Shared.GameObjects.Components.Movement;
 using Robust.Shared.Interfaces.Physics;
 using Robust.Shared.IoC;
 using Robust.Shared.Maths;
@@ -6,7 +6,7 @@ using Robust.Shared.Physics;
 
 namespace Content.Shared.Physics
 {
-    public class MoverController: VirtualController
+    public class MoverController : VirtualController
     {
         private Vector2 _velocity;
         private SharedPhysicsComponent _component = null;
@@ -29,7 +29,8 @@ namespace Content.Shared.Physics
 
         public void Move(Vector2 velocityDirection, float speed)
         {
-            if (IoCManager.Resolve<IPhysicsManager>().IsWeightless(_component.Owner.Transform.GridPosition)) return;
+            if (!_component.Owner.HasComponent<MovementIgnoreGravityComponent>() && IoCManager
+                .Resolve<IPhysicsManager>().IsWeightless(_component.Owner.Transform.GridPosition)) return;
             Push(velocityDirection, speed);
         }
 

Resources/Prototypes/Entities/Mobs/observer.yml

@@ -26,3 +26,5 @@
   - type: MovementSpeedModifier
     baseSprintSpeed: 14
     baseWalkSpeed: 7
+
+  - type: MovementIgnoreGravity