feat: add double overload for Bias (#60)

X10D.Tests/src/Math/MathUtilityTests.cs

@@ -1,4 +1,4 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 #if !NET6_0_OR_GREATER
 using X10D.Core;
 #endif
@@ -12,36 +12,31 @@ public class MathUtilityTests
     [TestMethod]
     public void Bias_ReturnsCorrectResult_WhenBiasIsLessThanPointFive()
     {
-        const float value = 0.5f;
+        double doubleResult = MathUtility.Bias(0.5, 0.3);
-        const float bias = 0.3f;
+        float floatResult = MathUtility.Bias(0.5f, 0.3f);
 
-        const float expected = 0.3f;
+        Assert.AreEqual(0.3, doubleResult, 1e-4);
-        float result = MathUtility.Bias(value, bias);
+        Assert.AreEqual(0.3f, floatResult, 1e-4f);
-
-        Assert.AreEqual(expected, result, 1e-6f);
     }
 
     [TestMethod]
     public void Bias_ReturnsCorrectResult_WhenBiasIsEqualToPointFive()
     {
-        const float value = 0.5f;
+        double doubleResult = MathUtility.Bias(0.5, 0.5);
-        const float bias = 0.5f;
+        float floatResult = MathUtility.Bias(0.5f, 0.5f);
 
-        float result = MathUtility.Bias(value, bias);
+        Assert.AreEqual(0.5, doubleResult, 1e-4);
-
+        Assert.AreEqual(0.5f, floatResult, 1e-4f);
-        Assert.AreEqual(value, result, 1e-6f);
     }
 
     [TestMethod]
     public void Bias_ReturnsCorrectResult_WhenBiasIsGreaterThanPointFive()
     {
-        const float value = 0.5f;
+        double doubleResult = MathUtility.Bias(0.5, 0.8);
-        const float bias = 0.8f;
+        float floatResult = MathUtility.Bias(0.5f, 0.8f);
 
-        const float expected = 0.8f;
+        Assert.AreEqual(0.8, doubleResult, 1e-4);
-        float result = MathUtility.Bias(value, bias);
+        Assert.AreEqual(0.8f, floatResult, 1e-4f);
-
-        Assert.AreEqual(expected, result, 1e-6f);
     }
 
     [TestMethod]
@@ -50,8 +45,8 @@ public class MathUtilityTests
         double doubleResult = MathUtility.GammaToLinear(0.25, 1.0);
         float floatResult = MathUtility.GammaToLinear(0.25f, 1.0f);
 
-        Assert.AreEqual(0.25, doubleResult);
+        Assert.AreEqual(0.25, doubleResult, 1e-6);
-        Assert.AreEqual(0.25f, floatResult);
+        Assert.AreEqual(0.25f, floatResult, 1e-6f);
     }
 
     [TestMethod]

X10D/src/Math/MathUtility.cs

@@ -25,6 +25,20 @@ public static class MathUtility
         return value / ((1.0f / bias - 2.0f) * (1.0f - value) + 1.0f);
     }
 
+    /// <summary>
+    ///     Applies a simple bias function to value.
+    /// </summary>
+    /// <param name="value">The value to which the bias function will be applied.</param>
+    /// <param name="bias">The bias value. Valid values range from 0-1.</param>
+    /// <returns>The biased result.</returns>
+    /// <remarks>
+    ///     If <paramref name="bias" /> is less than 0.5, <paramref name="value" /> will be shifted downward; otherwise, upward.
+    /// </remarks>
+    public static double Bias(double value, double bias)
+    {
+        return value / ((1.0 / bias - 2.0) * (1.0 - value) + 1.0);
+    }
+
     /// <summary>
     ///     Converts a gamma-encoded value to a linear value using a gamma value of <c>2.2</c>.
     /// </summary>