Add nitrous oxide decomposition reaction (#22738)

Co-authored-by: whateverusername0 <whateveremail>
Co-authored-by: Kevin Zheng <kevinz5000@gmail.com>

Content.Server/Atmos/Reactions/N2ODecompositionReaction.cs

@@ -0,0 +1,28 @@
+using Content.Server.Atmos.EntitySystems;
+using Content.Shared.Atmos;
+using JetBrains.Annotations;
+
+namespace Content.Server.Atmos.Reactions;
+
+/// <summary>
+///     Decomposes Nitrous Oxide into Nitrogen and Oxygen.
+/// </summary>
+[UsedImplicitly]
+public sealed partial class N2ODecompositionReaction : IGasReactionEffect
+{
+    public ReactionResult React(GasMixture mixture, IGasMixtureHolder? holder, AtmosphereSystem atmosphereSystem, float heatScale)
+    {
+        var cacheN2O = mixture.GetMoles(Gas.NitrousOxide);
+
+        var burnedFuel = cacheN2O / Atmospherics.N2ODecompositionRate;
+
+        if (burnedFuel <= 0 || cacheN2O - burnedFuel < 0)
+            return ReactionResult.NoReaction;
+
+        mixture.AdjustMoles(Gas.NitrousOxide, -burnedFuel);
+        mixture.AdjustMoles(Gas.Nitrogen, burnedFuel);
+        mixture.AdjustMoles(Gas.Oxygen, burnedFuel / 2);
+
+        return ReactionResult.Reacting;
+    }
+}

Content.Shared/Atmos/Atmospherics.cs

@@ -236,6 +236,11 @@ namespace Content.Shared.Atmos
         /// </summary>
         public const float FrezonProductionConversionRate = 50f;
 
+        /// <summary>
+        ///     The maximum portion of the N2O that can decompose each reaction tick. (50%)
+        /// </summary>
+        public const float N2ODecompositionRate = 2f;
+
         /// <summary>
         ///     How many mol of frezon can be converted into miasma in one cycle.
         /// </summary>

Resources/Prototypes/Atmospherics/reactions.yml

@@ -1,4 +1,4 @@
-- type: gasReaction
+- type: gasReaction
   id: PlasmaFire
   priority: -2
   minimumTemperature: 373.149 # Same as Atmospherics.FireMinimumTemperatureToExist
@@ -91,6 +91,23 @@
   effects:
   - !type:MiasmaOxygenReaction {}
 
+- type: gasReaction
+  id: N2ODecomposition
+  priority: 0
+  minimumTemperature: 850
+  minimumRequirements:
+  - 0     # oxygen
+  - 0     # nitrogen
+  - 0     # carbon dioxide
+  - 0     # plasma
+  - 0     # tritium
+  - 0     # vapor
+  - 0     # miasma
+  - 0.01  # n2o
+  - 0     # frezon
+  effects:
+  - !type:N2ODecompositionReaction {}
+
 #- type: gasReaction
 #  id: WaterVaporPuddle
 #  priority: 1