Add prediction for standing states and mob states (#1937)

Content.Server/GameObjects/Components/Mobs/State/DeadState.cs

@@ -0,0 +1,62 @@
+using Content.Server.GameObjects.EntitySystems;
+using Content.Shared.GameObjects.Components.Damage;
+using Content.Shared.GameObjects.Components.Mobs;
+using Content.Shared.GameObjects.Components.Mobs.State;
+using Robust.Server.GameObjects;
+using Robust.Shared.GameObjects.Components;
+using Robust.Shared.GameObjects.Systems;
+using Robust.Shared.Interfaces.GameObjects;
+
+namespace Content.Server.GameObjects.Components.Mobs.State
+{
+    public class DeadState : SharedDeadState
+    {
+        public override void EnterState(IEntity entity)
+        {
+            if (entity.TryGetComponent(out AppearanceComponent appearance))
+            {
+                appearance.SetData(DamageStateVisuals.State, DamageState.Dead);
+            }
+
+            if (entity.TryGetComponent(out ServerStatusEffectsComponent status))
+            {
+                status.ChangeStatusEffectIcon(StatusEffect.Health,
+                    "/Textures/Interface/StatusEffects/Human/humandead.png");
+            }
+
+            if (entity.TryGetComponent(out ServerOverlayEffectsComponent overlayComponent))
+            {
+                overlayComponent.AddOverlay(SharedOverlayID.CircleMaskOverlay);
+            }
+
+            if (entity.TryGetComponent(out StunnableComponent stun))
+            {
+                stun.CancelAll();
+            }
+
+            EntitySystem.Get<StandingStateSystem>().Down(entity);
+
+            if (entity.TryGetComponent(out CollidableComponent collidable))
+            {
+                collidable.CanCollide = false;
+            }
+        }
+
+        public override void ExitState(IEntity entity)
+        {
+            EntitySystem.Get<StandingStateSystem>().Standing(entity);
+
+            if (entity.TryGetComponent(out CollidableComponent collidable))
+            {
+                collidable.CanCollide = true;
+            }
+
+            if (entity.TryGetComponent(out ServerOverlayEffectsComponent overlay))
+            {
+                overlay.ClearOverlays();
+            }
+        }
+
+        public override void UpdateState(IEntity entity) { }
+    }
+}