From f64b84551423b02ce2f66092769f3ab3bfbb7740 Mon Sep 17 00:00:00 2001
From: Raul Santos <raulsntos@gmail.com>
Date: Sat, 27 Aug 2022 10:28:00 +0200
Subject: [PATCH] C#: Add `CubicInterpolateAngle`

---
 .../glue/GodotSharp/GodotSharp/Core/Mathf.cs  | 60 +++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Mathf.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Mathf.cs
index 124410a1c2d..b30012d2145 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Mathf.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Mathf.cs
@@ -193,6 +193,33 @@ namespace Godot
                             (-pre + 3.0f * from - 3.0f * to + post) * (weight * weight * weight));
         }
 
+        /// <summary>
+        /// Cubic interpolates between two rotation values with shortest path
+        /// by the factor defined in <paramref name="weight"/> with pre and post values.
+        /// See also <see cref="LerpAngle"/>.
+        /// </summary>
+        /// <param name="from">The start value for interpolation.</param>
+        /// <param name="to">The destination value for interpolation.</param>
+        /// <param name="pre">The value which before "from" value for interpolation.</param>
+        /// <param name="post">The value which after "to" value for interpolation.</param>
+        /// <param name="weight">A value on the range of 0.0 to 1.0, representing the amount of interpolation.</param>
+        /// <returns>The resulting value of the interpolation.</returns>
+        public static real_t CubicInterpolateAngle(real_t from, real_t to, real_t pre, real_t post, real_t weight)
+        {
+            real_t fromRot = from % Mathf.Tau;
+
+            real_t preDiff = (pre - fromRot) % Mathf.Tau;
+            real_t preRot = fromRot + (2.0f * preDiff) % Mathf.Tau - preDiff;
+
+            real_t toDiff = (to - fromRot) % Mathf.Tau;
+            real_t toRot = fromRot + (2.0f * toDiff) % Mathf.Tau - toDiff;
+
+            real_t postDiff = (post - toRot) % Mathf.Tau;
+            real_t postRot = toRot + (2.0f * postDiff) % Mathf.Tau - postDiff;
+
+            return CubicInterpolate(fromRot, toRot, preRot, postRot, weight);
+        }
+
         /// <summary>
         /// Cubic interpolates between two values by the factor defined in <paramref name="weight"/>
         /// with pre and post values.
@@ -220,6 +247,39 @@ namespace Godot
             return Lerp(b1, b2, toT == 0 ? 0.5f : t / toT);
         }
 
+        /// <summary>
+        /// Cubic interpolates between two rotation values with shortest path
+        /// by the factor defined in <paramref name="weight"/> with pre and post values.
+        /// See also <see cref="LerpAngle"/>.
+        /// It can perform smoother interpolation than <see cref="CubicInterpolateAngle"/>
+        /// by the time values.
+        /// </summary>
+        /// <param name="from">The start value for interpolation.</param>
+        /// <param name="to">The destination value for interpolation.</param>
+        /// <param name="pre">The value which before "from" value for interpolation.</param>
+        /// <param name="post">The value which after "to" value for interpolation.</param>
+        /// <param name="weight">A value on the range of 0.0 to 1.0, representing the amount of interpolation.</param>
+        /// <param name="toT"></param>
+        /// <param name="preT"></param>
+        /// <param name="postT"></param>
+        /// <returns>The resulting value of the interpolation.</returns>
+        public static real_t CubicInterpolateAngleInTime(real_t from, real_t to, real_t pre, real_t post, real_t weight,
+                    real_t toT, real_t preT, real_t postT)
+        {
+            real_t fromRot = from % Mathf.Tau;
+
+            real_t preDiff = (pre - fromRot) % Mathf.Tau;
+            real_t preRot = fromRot + (2.0f * preDiff) % Mathf.Tau - preDiff;
+
+            real_t toDiff = (to - fromRot) % Mathf.Tau;
+            real_t toRot = fromRot + (2.0f * toDiff) % Mathf.Tau - toDiff;
+
+            real_t postDiff = (post - toRot) % Mathf.Tau;
+            real_t postRot = toRot + (2.0f * postDiff) % Mathf.Tau - postDiff;
+
+            return CubicInterpolateInTime(fromRot, toRot, preRot, postRot, weight, toT, preT, postT);
+        }
+
         /// <summary>
         /// Returns the point at the given <paramref name="t"/> on a one-dimensional Bezier curve defined by
         /// the given <paramref name="control1"/>, <paramref name="control2"/> and <paramref name="end"/> points.