Atmos GetAirflowDirections API (#42668)

Content.IntegrationTests/Tests/Atmos/GetAirflowDirectionsTest.cs

@@ -0,0 +1,50 @@
+using Content.Server.Atmos.EntitySystems;
+using Content.Shared.Atmos;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Map;
+using Robust.Shared.Maths;
+using Robust.Shared.Utility;
+
+namespace Content.IntegrationTests.Tests.Atmos;
+
+/// <summary>
+/// Class for testing some airflow retrieval API methods.
+/// </summary>
+public sealed class GetAirflowDirectionsTest : AtmosTest
+{
+    // i will keep using this test map until it has been drained
+    // of all use
+    protected override ResPath? TestMapPath => new("Maps/Test/Atmospherics/DeltaPressure/deltapressuretest.yml");
+
+    [Test]
+    [TestCase(0, 0, AtmosDirection.All)]
+    [TestCase(0, 1, AtmosDirection.South)]
+    [TestCase(0, -1, AtmosDirection.North)]
+    [TestCase(1, 0, AtmosDirection.West)]
+    [TestCase(-1, 0, AtmosDirection.East)]
+    [TestCase(1, 1, AtmosDirection.Invalid)]
+    [TestCase(100, 100, AtmosDirection.Invalid)]
+    public async Task TestLookup(int x, int y, AtmosDirection expectedDirections)
+    {
+        await Server.WaitPost(delegate
+        {
+            // yea
+            var coords = new Vector2i(x, y);
+            var directions = SAtmos.GetAirflowDirections(RelevantAtmos, coords);
+            Assert.That(directions, Is.EqualTo(expectedDirections));
+        });
+    }
+
+    /// <summary>
+    /// Tests that a grident with no atmosphere will return <see cref="AtmosDirection.Invalid"/>.
+    /// </summary>
+    [Test]
+    public async Task TestLookup_BadEnt()
+    {
+        await Server.WaitPost(delegate
+        {
+            var directions = SAtmos.GetAirflowDirections(EntityUid.Invalid, Vector2i.Zero);
+            Assert.That(directions, Is.EqualTo(AtmosDirection.Invalid));
+        });
+    }
+}

Content.Server/Atmos/EntitySystems/AtmosphereSystem.API.cs

@@ -350,6 +350,29 @@ public partial class AtmosphereSystem
         return atmosTile.AirtightData.BlockedDirections.IsFlagSet(directions);
     }
 
+    /// <summary>
+    /// Returns the <see cref="TileAtmosphere.AdjacentBits"/> for a tile on a grid.
+    /// This represents the directions that the air can currently flow to.
+    /// </summary>
+    /// <param name="grid">The grid entity that the tile belongs to.</param>
+    /// <param name="tile">The <see cref="Vector2i"/> coordinates to check.</param>
+    /// <returns>The <see cref="TileAtmosphere.AdjacentBits"/> of the tile,
+    /// <see cref="AtmosDirection.Invalid"/> if the grid or tile couldn't be found.</returns>
+    /// <remarks>Note that this data is cached and is updated at the beginning of every atmostick.
+    /// As such, any airtight changes that were made may not be reflected in this value until
+    /// the cache is refreshed in the next processing tick.</remarks>
+    [PublicAPI]
+    public AtmosDirection GetAirflowDirections(Entity<GridAtmosphereComponent?> grid, Vector2i tile)
+    {
+        if (!_atmosQuery.Resolve(grid, ref grid.Comp, false))
+            return AtmosDirection.Invalid;
+
+        if (!grid.Comp.Tiles.TryGetValue(tile, out var atmosTile))
+            return AtmosDirection.Invalid;
+
+        return atmosTile.AdjacentBits;
+    }
+
     /// <summary>
     /// Checks if a tile on a grid or map is space as defined by a tile's definition of space.
     /// Some tiles can hold back space and others cannot - for example, plating can hold