Atmos debug helpers (#2108)

* Atmos debug overlay

* Pressure direction information

* Atmos debug overlay: show excited tiles

Content.Shared/GameObjects/EntitySystems/Atmos/SharedAtmosDebugOverlaySystem.cs

@@ -0,0 +1,56 @@
+using System;
+using System.Collections.Generic;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Systems;
+using Robust.Shared.Map;
+using Robust.Shared.Serialization;
+using Robust.Shared.Utility;
+using Content.Shared.Atmos;
+
+namespace Content.Shared.GameObjects.EntitySystems.Atmos
+{
+    public abstract class SharedAtmosDebugOverlaySystem : EntitySystem
+    {
+        // Keep in mind, this system is hilariously unoptimized. The goal here is to provide accurate debug data.
+        public const int LocalViewRange = 16;
+        protected float AccumulatedFrameTime;
+
+        [Serializable, NetSerializable]
+        public readonly struct AtmosDebugOverlayData
+        {
+            public readonly float Temperature;
+            public readonly float[] Moles;
+            public readonly AtmosDirection PressureDirection;
+            public readonly bool InExcitedGroup;
+
+            public AtmosDebugOverlayData(float temperature, float[] moles, AtmosDirection pressureDirection, bool inExcited)
+            {
+                Temperature = temperature;
+                Moles = moles;
+                PressureDirection = pressureDirection;
+                InExcitedGroup = inExcited;
+            }
+        }
+
+        /// <summary>
+        ///     Invalid tiles for the gas overlay.
+        ///     No point re-sending every tile if only a subset might have been updated.
+        /// </summary>
+        [Serializable, NetSerializable]
+        public sealed class AtmosDebugOverlayMessage : EntitySystemMessage
+        {
+            public GridId GridId { get; }
+
+            public MapIndices BaseIdx { get; }
+            // LocalViewRange*LocalViewRange
+            public AtmosDebugOverlayData[] OverlayData { get; }
+
+            public AtmosDebugOverlayMessage(GridId gridIndices, MapIndices baseIdx, AtmosDebugOverlayData[] overlayData)
+            {
+                GridId = gridIndices;
+                BaseIdx = baseIdx;
+                OverlayData = overlayData;
+            }
+        }
+    }
+}