carpet (#5464)

* carpet

* reviews

* why tf i gotta fix integration tests in the carpet pr

Content.Server/Chemistry/Components/SolutionAreaEffectComponent.cs

@@ -29,6 +29,11 @@ namespace Content.Server.Chemistry.Components
         public int Amount { get; set; }
         public SolutionAreaEffectInceptionComponent? Inception { get; set; }
 
+        /// <summary>
+        ///     Have we reacted with our tile yet?
+        /// </summary>
+        public bool ReactedTile = false;
+
         /// <summary>
         /// Adds an <see cref="SolutionAreaEffectInceptionComponent"/> to owner so the effect starts spreading and reacting.
         /// </summary>
@@ -138,7 +143,12 @@ namespace Content.Server.Chemistry.Components
                 var reagent = PrototypeManager.Index<ReagentPrototype>(reagentQuantity.ReagentId);
 
                 // React with the tile the effect is on
-                reagent.ReactionTile(tile, reagentQuantity.Quantity * solutionFraction);
+                // We don't multiply by solutionFraction here since the tile is only ever reacted once
+                if (!ReactedTile)
+                {
+                    reagent.ReactionTile(tile, reagentQuantity.Quantity);
+                    ReactedTile = true;
+                }
 
                 // Touch every entity on the tile
                 foreach (var entity in tile.GetEntitiesInTileFast().ToArray())

Content.Server/Chemistry/TileReactions/CreateEntityReaction.cs

@@ -0,0 +1,63 @@
+using Content.Shared.Chemistry.Reaction;
+using Content.Shared.Chemistry.Reagent;
+using Content.Shared.FixedPoint;
+using Content.Shared.Maps;
+using Content.Shared.Whitelist;
+using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Map;
+using Robust.Shared.Maths;
+using Robust.Shared.Prototypes;
+using Robust.Shared.Serialization.Manager.Attributes;
+using Robust.Shared.Serialization.TypeSerializers.Implementations.Custom.Prototype;
+
+namespace Content.Server.Chemistry.TileReactions;
+
+[DataDefinition]
+public class CreateEntityReaction : ITileReaction
+{
+    [DataField("entity", required: true, customTypeSerializer:typeof(PrototypeIdSerializer<EntityPrototype>))]
+    public string Entity = default!;
+
+    [DataField("usage")]
+    public FixedPoint2 Usage = FixedPoint2.New(1);
+
+    /// <summary>
+    ///     How many of the whitelisted entity can fit on one tile?
+    /// </summary>
+    [DataField("maxOnTile")]
+    public int MaxOnTile = 1;
+
+    /// <summary>
+    ///     The whitelist to use when determining what counts as "max entities on a tile".0
+    /// </summary>
+    [DataField("maxOnTileWhitelist")]
+    public EntityWhitelist? Whitelist;
+
+    public FixedPoint2 TileReact(TileRef tile, ReagentPrototype reagent, FixedPoint2 reactVolume)
+    {
+        if (reactVolume >= Usage)
+        {
+            // TODO probably pass this in args like reagenteffects do.
+            var entMan = IoCManager.Resolve<IEntityManager>();
+
+            if (Whitelist != null)
+            {
+                int acc = 0;
+                foreach (var ent in tile.GetEntitiesInTile())
+                {
+                    if (Whitelist.IsValid(ent.Uid))
+                        acc += 1;
+
+                    if (acc >= MaxOnTile)
+                        return FixedPoint2.Zero;
+                }
+            }
+
+            entMan.SpawnEntity(Entity, tile.GridPosition().Offset(new Vector2(0.5f, 0.5f)));
+            return Usage;
+        }
+
+        return FixedPoint2.Zero;
+    }
+}