From 1939bbe4ba748c4ff5f6501d164ed6670904f780 Mon Sep 17 00:00:00 2001
From: Oliver Booth <me@olivr.me>
Date: Mon, 3 Apr 2023 17:15:11 +0100
Subject: [PATCH] feat: add MathUtility.Sawtooth (#60)

---
 CHANGELOG.md                            |  1 +
 X10D.Tests/src/Math/MathUtilityTests.cs | 66 +++++++++++++++++++++++++
 X10D/src/Math/MathUtility.cs            | 20 ++++++++
 3 files changed, 87 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 512b4b3..4b5c2ae 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - X10D: Added `MathUtility.Bias(float, float)` and `MathUtility.Bias(double, double)`.
 - X10D: Added `MathUtility.ExponentialDecay(float, float, float)` and `MathUtility.ExponentialDecay(double, double, double)`.
 - X10D: Added `MathUtility.InverseLerp(float, float, float)` and `MathUtility.InverseLerp(double, double, double)`.
+- X10D: Added `MathUtility.Sawtooth(float)` and `MathUtility.Sawtooth(double)`.
 - X10D: Added `MathUtility.ScaleRange(float, float, float, float, float)`
   and `MathUtility.ScaleRange(double, double, double, double, double)`
 - X10D: Added `MathUtility.Sigmoid(float)` and `MathUtility.Sigmoid(double)`.
diff --git a/X10D.Tests/src/Math/MathUtilityTests.cs b/X10D.Tests/src/Math/MathUtilityTests.cs
index 45c37ab..f58835c 100644
--- a/X10D.Tests/src/Math/MathUtilityTests.cs
+++ b/X10D.Tests/src/Math/MathUtilityTests.cs
@@ -163,6 +163,72 @@ public class MathUtilityTests
         Assert.AreEqual(1.0f, floatResult);
     }
 
+    [TestMethod]
+    public void Sawtooth_ShouldReturn0Point5_Given0Point5AsDouble()
+    {
+        const double value = 0.5;
+
+        const double expected = 0.5;
+        double actual = MathUtility.Sawtooth(value);
+
+        Assert.AreEqual(expected, actual, 1e-6);
+    }
+
+    [TestMethod]
+    public void Sawtooth_ShouldReturn0Point5_Given0Point5AsSingle()
+    {
+        const float value = 0.5f;
+
+        const float expected = 0.5f;
+        float actual = MathUtility.Sawtooth(value);
+
+        Assert.AreEqual(expected, actual, 1e-6f);
+    }
+
+    [TestMethod]
+    public void Sawtooth_ShouldReturn0Point5_Given1Point5AsDouble()
+    {
+        const double value = 1.5;
+
+        const double expected = 0.5;
+        double actual = MathUtility.Sawtooth(value);
+
+        Assert.AreEqual(expected, actual, 1e-6);
+    }
+
+    [TestMethod]
+    public void Sawtooth_ShouldReturn0Point5_Given1Point5AsSingle()
+    {
+        const float value = 1.5f;
+
+        const float expected = 0.5f;
+        float actual = MathUtility.Sawtooth(value);
+
+        Assert.AreEqual(expected, actual, 1e-6f);
+    }
+
+    [TestMethod]
+    public void Sawtooth_ShouldReturn0Point5_GivenNegative1Point5AsDouble()
+    {
+        const double value = -1.5;
+
+        const double expected = 0.5;
+        double actual = MathUtility.Sawtooth(value);
+
+        Assert.AreEqual(expected, actual, 1e-6);
+    }
+
+    [TestMethod]
+    public void Sawtooth_ShouldReturn0Point5_GivenNegative1Point5AsSingle()
+    {
+        const float value = -1.5f;
+
+        const float expected = 0.5f;
+        float actual = MathUtility.Sawtooth(value);
+
+        Assert.AreEqual(expected, actual, 1e-6f);
+    }
+
     [TestMethod]
     public void ScaleRangeDouble_ShouldScaleRange_GivenItsValues()
     {
diff --git a/X10D/src/Math/MathUtility.cs b/X10D/src/Math/MathUtility.cs
index dc9b2f7..18d0009 100644
--- a/X10D/src/Math/MathUtility.cs
+++ b/X10D/src/Math/MathUtility.cs
@@ -287,6 +287,26 @@ public static class MathUtility
         return System.Math.Pow(value, 1.0 / gamma);
     }
 
+    /// <summary>
+    ///     Returns the incremental sawtooth wave of a given value.
+    /// </summary>
+    /// <param name="value">The value to calculate.</param>
+    /// <returns>The sawtooth wave of the given value.</returns>
+    public static float Sawtooth(float value)
+    {
+        return (value - MathF.Floor(value));
+    }
+
+    /// <summary>
+    ///     Returns the incremental sawtooth wave of a given value.
+    /// </summary>
+    /// <param name="value">The value to calculate.</param>
+    /// <returns>The sawtooth wave of the given value.</returns>
+    public static double Sawtooth(double value)
+    {
+        return (value - System.Math.Floor(value));
+    }
+
     /// <summary>
     ///     Converts a value from being a percentage of one range, to being the same percentage in a new range.
     /// </summary>