Fix gravity shenanigans (#12866)

Content.Shared/Gravity/SharedGravitySystem.Shake.cs

@@ -0,0 +1,87 @@
+using Robust.Shared.GameStates;
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.Gravity;
+
+public abstract partial class SharedGravitySystem
+{
+    protected const float GravityKick = 100.0f;
+    protected const float ShakeCooldown = 0.2f;
+
+    private void InitializeShake()
+    {
+        SubscribeLocalEvent<GravityShakeComponent, EntityUnpausedEvent>(OnShakeUnpaused);
+        SubscribeLocalEvent<GravityShakeComponent, ComponentGetState>(OnShakeGetState);
+        SubscribeLocalEvent<GravityShakeComponent, ComponentHandleState>(OnShakeHandleState);
+    }
+
+    private void OnShakeUnpaused(EntityUid uid, GravityShakeComponent component, ref EntityUnpausedEvent args)
+    {
+        component.NextShake += args.PausedTime;
+    }
+
+    private void UpdateShake()
+    {
+        var curTime = Timing.CurTime;
+        var gravityQuery = GetEntityQuery<GravityComponent>();
+
+        foreach (var comp in EntityQuery<GravityShakeComponent>())
+        {
+            if (comp.NextShake <= curTime)
+            {
+                if (comp.ShakeTimes == 0 || !gravityQuery.TryGetComponent(comp.Owner, out var gravity))
+                {
+                    RemCompDeferred<GravityShakeComponent>(comp.Owner);
+                    continue;
+                }
+
+                ShakeGrid(comp.Owner, gravity);
+                comp.ShakeTimes--;
+                comp.NextShake += TimeSpan.FromSeconds(ShakeCooldown);
+                Dirty(comp);
+            }
+        }
+    }
+
+    public void StartGridShake(EntityUid uid, GravityComponent? gravity = null)
+    {
+        if (!Resolve(uid, ref gravity, false))
+            return;
+
+        if (!TryComp<GravityShakeComponent>(uid, out var shake))
+        {
+            shake = AddComp<GravityShakeComponent>(uid);
+            shake.NextShake = Timing.CurTime;
+        }
+
+        shake.ShakeTimes = 10;
+        Dirty(shake);
+    }
+
+    protected virtual void ShakeGrid(EntityUid uid, GravityComponent? comp = null) {}
+
+    private void OnShakeHandleState(EntityUid uid, GravityShakeComponent component, ref ComponentHandleState args)
+    {
+        if (args.Current is not GravityShakeComponentState state)
+            return;
+
+        component.ShakeTimes = state.ShakeTimes;
+        component.NextShake = state.NextShake;
+    }
+
+    private void OnShakeGetState(EntityUid uid, GravityShakeComponent component, ref ComponentGetState args)
+    {
+        args.State = new GravityShakeComponentState()
+        {
+            ShakeTimes = component.ShakeTimes,
+            NextShake = component.NextShake,
+        };
+    }
+
+    [Serializable, NetSerializable]
+    protected sealed class GravityShakeComponentState : ComponentState
+    {
+        public int ShakeTimes;
+        public TimeSpan NextShake;
+    }
+}