Fueled Thrusters

Content.Server/Atmos/EntitySystems/AtmoshpereSystem.EsHelpers.cs

@@ -0,0 +1,123 @@
+using Content.Shared.Atmos;
+
+namespace Content.Server.Atmos.EntitySystems;
+
+public sealed partial class AtmosphereSystem
+{
+    /// <summary>
+    /// Compares two <see cref="GasMixture"/>s and returns a similarity score between 0 and 1,
+    /// based entirely on the percent compositions of the <see cref="GasMixture"/>s.
+    /// </summary>
+    /// <param name="a">The first <see cref="GasMixture"/> to compare.</param>
+    /// <param name="b">The second <see cref="GasMixture"/> to compare.</param>
+    /// <returns>A float between 0 and 1 based on how similar the gas mixtures are,
+    /// based on percent compositions. This method will also return zero if one compared GasMixture is empty.</returns>
+    public float GetGasMixtureSimilarity(GasMixture? a, GasMixture? b)
+    {
+        // Naive.
+        if (a == null || b == null)
+            return 0f;
+
+        var aArr = a.Moles;
+        var bArr = b.Moles;
+        var len = aArr.Length;
+
+        var totalA = NumericsHelpers.HorizontalAdd(aArr);
+        var totalB = NumericsHelpers.HorizontalAdd(bArr);
+
+        // If both mixtures are empty, consider them identical.
+        if (totalA <= 0f && totalB <= 0f)
+            return 1f;
+
+        float numerator = 0f, denominator = Math.Max(totalA, totalB);
+
+        // Normalize each gas mole value by dividing it by its total moles
+        for (var i = 0; i < len; i++)
+        {
+            // Protect against Div/0 for each normalization
+            var normalizedA = totalA > 0f ? aArr[i] / totalA : 0f;
+            var normalizedB = totalB > 0f ? bArr[i] / totalB : 0f;
+
+            numerator += Math.Min(normalizedA, normalizedB);
+        }
+
+        // Fall back to 1 if no valid denominator is present
+        // Abs comparison because platform dependent FPU behavior
+        return Math.Abs(denominator) < 0.001f ? 1f : numerator;
+    }
+
+    /// <summary>
+    /// Returns the percentage (0-1) of each gas in the mixture.
+    /// </summary>
+    public static float[] GetGasPercentages(GasMixture mixture)
+    {
+        var total = mixture.TotalMoles;
+        var result = new float[mixture.Moles.Length];
+
+        if (total <= 0f)
+        {
+            return result;
+        }
+
+        for (var i = 0; i < mixture.Moles.Length; i++)
+        {
+            result[i] = mixture.Moles[i] / total;
+        }
+
+        return result;
+    }
+
+    /// <summary>
+    /// Returns true if all gases in the target mixture are present in the source mixture above a threshold percentage.
+    /// </summary>
+    public static bool HasGasesAboveThreshold(GasMixture target, GasMixture source, float threshold = 0.01f)
+    {
+        var targetPerc = GetGasPercentages(target);
+        var sourcePerc = GetGasPercentages(source);
+
+        // Check if each gas in the target mixture is present in the source mixture above the threshold.
+        // If one doesn't match, we return false.
+        for (var i = 0; i < targetPerc.Length; i++)
+        {
+            if (targetPerc[i] > 0f && sourcePerc[i] < targetPerc[i] - threshold)
+                return false;
+        }
+        return true;
+    }
+
+    /// <summary>
+    /// Returns the minimum ratio of source/target for all gases present in the target mixture.
+    /// </summary>
+    public static float GetPurityRatio(GasMixture target, GasMixture source)
+    {
+        var targetPerc = GetGasPercentages(target);
+        var sourcePerc = GetGasPercentages(source);
+        var min = 1f;
+        for (var i = 0; i < targetPerc.Length; i++)
+        {
+            if (targetPerc[i] > 0f)
+            {
+                if (sourcePerc[i] <= 0f)
+                    return 0f;
+                min = Math.Min(min, sourcePerc[i] / targetPerc[i]);
+            }
+        }
+        return Math.Clamp(min, 0f, 1f);
+    }
+
+    /// <summary>
+    /// Returns true if any gas in the target mixture is present in the source mixture above a threshold.
+    /// </summary>
+    public static bool HasAnyRequiredGas(GasMixture target, GasMixture source, float threshold = 0.01f)
+    {
+        var targetPerc = GetGasPercentages(target);
+        var sourcePerc = GetGasPercentages(source);
+
+        for (var i = 0; i < targetPerc.Length; i++)
+        {
+            if (targetPerc[i] > 0f && sourcePerc[i] > threshold)
+                return true;
+        }
+        return false;
+    }
+}