Gas tile overlay rejig (#9619)

Content.Server/Chunking/ChunkingSystem.cs

@@ -0,0 +1,104 @@
+using Content.Shared.Decals;
+using Microsoft.Extensions.ObjectPool;
+using Robust.Server.Player;
+using Robust.Shared;
+using Robust.Shared.Configuration;
+using Robust.Shared.Enums;
+using Robust.Shared.Map;
+using Robust.Shared.Utility;
+
+namespace Content.Shared.Chunking;
+
+/// <summary>
+///     This system just exists to provide some utility functions for other systems that chunk data that needs to be
+///     sent to players. In particular, see <see cref="GetChunksForSession"/>.
+/// </summary>
+public sealed class ChunkingSystem : EntitySystem
+{
+    [Dependency] private readonly IConfigurationManager _configurationManager = default!;
+    [Dependency] private readonly IMapManager _mapManager = default!;
+    [Dependency] private readonly SharedTransformSystem _transform = default!;
+
+    private Box2 _baseViewBounds;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        _configurationManager.OnValueChanged(CVars.NetMaxUpdateRange, OnPvsRangeChanged, true);
+    }
+
+    public override void Shutdown()
+    {
+        base.Shutdown();
+        _configurationManager.UnsubValueChanged(CVars.NetMaxUpdateRange, OnPvsRangeChanged);
+    }
+
+    private void OnPvsRangeChanged(float value) => _baseViewBounds = Box2.UnitCentered.Scale(value);
+
+    public Dictionary<EntityUid, HashSet<Vector2i>> GetChunksForSession(
+        IPlayerSession session,
+        int chunkSize,
+        EntityQuery<TransformComponent> xformQuery,
+        ObjectPool<HashSet<Vector2i>> indexPool,
+        ObjectPool<Dictionary<EntityUid, HashSet<Vector2i>>> viewerPool,
+        float? viewEnlargement = null)
+    {
+        var viewers = GetSessionViewers(session);
+        var chunks = GetChunksForViewers(viewers, chunkSize, indexPool, viewerPool, viewEnlargement ?? chunkSize, xformQuery);
+        return chunks;
+    }
+
+    private HashSet<EntityUid> GetSessionViewers(IPlayerSession session)
+    {
+        var viewers = new HashSet<EntityUid>();
+        if (session.Status != SessionStatus.InGame || session.AttachedEntity is null)
+            return viewers;
+
+        viewers.Add(session.AttachedEntity.Value);
+
+        foreach (var uid in session.ViewSubscriptions)
+        {
+            viewers.Add(uid);
+        }
+
+        return viewers;
+    }
+
+    private Dictionary<EntityUid, HashSet<Vector2i>> GetChunksForViewers(
+        HashSet<EntityUid> viewers,
+        int chunkSize,
+        ObjectPool<HashSet<Vector2i>> indexPool,
+        ObjectPool<Dictionary<EntityUid, HashSet<Vector2i>>> viewerPool,
+        float viewEnlargement,
+        EntityQuery<TransformComponent> xformQuery)
+    {
+        Dictionary<EntityUid, HashSet<Vector2i>> chunks = viewerPool.Get();
+        DebugTools.Assert(chunks.Count == 0);
+
+        foreach (var viewerUid in viewers)
+        {
+            var xform = xformQuery.GetComponent(viewerUid);
+            var pos = _transform.GetWorldPosition(xform, xformQuery);
+            var bounds = _baseViewBounds.Translated(pos).Enlarged(viewEnlargement);
+
+            foreach (var grid in _mapManager.FindGridsIntersecting(xform.MapID, bounds, true))
+            {
+                if (!chunks.TryGetValue(grid.GridEntityId, out var set))
+                {
+                    chunks[grid.GridEntityId] = set = indexPool.Get();
+                    DebugTools.Assert(set.Count == 0);
+                }
+
+                var enumerator = new ChunkIndicesEnumerator(_transform.GetInvWorldMatrix(grid.GridEntityId, xformQuery).TransformBox(bounds), chunkSize);
+
+                while (enumerator.MoveNext(out var indices))
+                {
+                    set.Add(indices.Value);
+                }
+            }
+        }
+
+        return chunks;
+    }
+}
+