Improve IsBlockedTurf (#15133)

Content.Shared/Maps/TurfSystem.cs

@@ -0,0 +1,88 @@
+using Content.Shared.Physics;
+using Robust.Shared.Map;
+using Robust.Shared.Map.Components;
+using Robust.Shared.Physics;
+
+namespace Content.Shared.Maps;
+
+/// <summary>
+///     This system provides various useful helper methods for turfs & tiles. Replacement for <see cref="TurfHelpers"/>
+/// </summary>
+public sealed class TurfSystem : EntitySystem
+{
+    [Dependency] private readonly IMapManager _mapMan = default!;
+    [Dependency] private readonly EntityLookupSystem _entityLookup = default!;
+    [Dependency] private readonly SharedTransformSystem _transform = default!;
+
+    /// <summary>
+    ///     Returns true if a given tile is blocked by physics-enabled entities.
+    /// </summary>
+    public bool IsTileBlocked(TileRef turf, CollisionGroup mask, float minIntersectionArea = 0.1f)
+        => IsTileBlocked(turf.GridUid, turf.GridIndices, mask, minIntersectionArea: minIntersectionArea);
+
+    /// <summary>
+    ///     Returns true if a given tile is blocked by physics-enabled entities.
+    /// </summary>
+    /// <param name="gridUid">The grid that owns the tile</param>
+    /// <param name="indices">The tile indices</param>
+    /// <param name="mask">Collision layers to check</param>
+    /// <param name="grid">Grid component</param>
+    /// <param name="gridXform">Grid's transform</param>
+    /// <param name="minIntersectionArea">Minimum area that must be covered for a tile to be considered blocked</param>
+    public bool IsTileBlocked(EntityUid gridUid,
+        Vector2i indices,
+        CollisionGroup mask,
+        MapGridComponent? grid = null,
+        TransformComponent? gridXform = null,
+        float minIntersectionArea = 0.1f)
+    {
+        if (!Resolve(gridUid, ref grid, ref gridXform))
+            return false;
+
+        var xformQuery = GetEntityQuery<TransformComponent>();
+        var (gridPos, gridRot, matrix) = _transform.GetWorldPositionRotationMatrix(gridXform, xformQuery);
+
+        var size = grid.TileSize;
+        var localPos = new Vector2(indices.X * size + (size / 2f), indices.Y * size + (size / 2f));
+        var worldPos = matrix.Transform(localPos);
+
+        // This is scaled to 95 % so it doesn't encompass walls on other tiles.
+        var tileAabb = Box2.UnitCentered.Scale(0.95f * size);
+        var worldBox = new Box2Rotated(tileAabb.Translated(worldPos), gridRot, worldPos);
+        tileAabb = tileAabb.Translated(localPos);
+
+        var intersectionArea = 0f;
+        var fixtureQuery = GetEntityQuery<FixturesComponent>();
+        foreach (var ent in _entityLookup.GetEntitiesIntersecting(gridUid, worldBox, LookupFlags.Dynamic | LookupFlags.Static))
+        {
+            if (!fixtureQuery.TryGetComponent(ent, out var fixtures))
+                continue;
+
+            // get grid local coordinates
+            var (pos, rot) = _transform.GetWorldPositionRotation(xformQuery.GetComponent(ent), xformQuery);
+            rot -= gridRot;
+            pos = (-gridRot).RotateVec(pos - gridPos);
+
+            var xform = new Transform(pos, (float) rot.Theta);
+
+            foreach (var fixture in fixtures.Fixtures.Values)
+            {
+                if (!fixture.Hard)
+                    continue;
+
+                if ((fixture.CollisionLayer & (int) mask) == 0)
+                    continue;
+
+                for (var i = 0; i < fixture.Shape.ChildCount; i++)
+                {
+                    var intersection = fixture.Shape.ComputeAABB(xform, i).Intersect(tileAabb);
+                    intersectionArea += intersection.Width * intersection.Height;
+                    if (intersectionArea > minIntersectionArea)
+                        return true;
+                }
+            }
+        }
+
+        return false;
+    }
+}