feat: add MathUtility.Bias (#60)

CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added new library X10D.Hosting.
 - Added .NET 7 target.
 - X10D: Added `IntrinsicExtensions` and `IntrinsicUtility` which offer methods for vectors in `System.Runtime.Instrinsics`. (#70)
+- X10D: Added `MathUtility.Bias(float, float)`.
 - X10D: Added `MathUtility.InverseLerp(float, float, float)` and `MathUtility.InverseLerp(double, double, double)`
 - X10D: Added `MathUtility.ScaleRange(float, float, float, float, float)`
   and `MathUtility.ScaleRange(double, double, double, double, double)`

X10D.Tests/src/Math/MathUtilityTests.cs

@@ -9,6 +9,41 @@ namespace X10D.Tests.Math;
 [TestClass]
 public class MathUtilityTests
 {
+    [TestMethod]
+    public void Bias_ReturnsCorrectResult_WhenBiasIsLessThanPointFive()
+    {
+        const float value = 0.5f;
+        const float bias = 0.3f;
+
+        const float expected = 0.3f;
+        float result = MathUtility.Bias(value, bias);
+
+        Assert.AreEqual(expected, result, 1e-6f);
+    }
+
+    [TestMethod]
+    public void Bias_ReturnsCorrectResult_WhenBiasIsEqualToPointFive()
+    {
+        const float value = 0.5f;
+        const float bias = 0.5f;
+
+        float result = MathUtility.Bias(value, bias);
+
+        Assert.AreEqual(value, result, 1e-6f);
+    }
+
+    [TestMethod]
+    public void Bias_ReturnsCorrectResult_WhenBiasIsGreaterThanPointFive()
+    {
+        const float value = 0.5f;
+        const float bias = 0.8f;
+
+        const float expected = 0.8f;
+        float result = MathUtility.Bias(value, bias);
+
+        Assert.AreEqual(expected, result, 1e-6f);
+    }
+
     [TestMethod]
     public void GammaToLinear_ShouldReturnQuarter_GivenQuarterAndGamma1()
     {

X10D/src/Math/MathUtility.cs

@@ -11,6 +11,20 @@ public static class MathUtility
     private const double DefaultGamma = 2.2;
     private const float DefaultGammaF = 2.2f;
 
+    /// <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 float Bias(float value, float bias)
+    {
+        return value / ((1.0f / bias - 2.0f) * (1.0f - value) + 1.0f);
+    }
+
     /// <summary>
     ///     Converts a gamma-encoded value to a linear value using a gamma value of <c>2.2</c>.
     /// </summary>