Add Easing to CinemachineSplineRoll

com.unity.cinemachine/CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Added
 - Added CinemachineVirtualCameraBaseEditor, to make it easier to make conformant inspectors for custom virtual cameras and virtual camera managers.
+- Added Easing option to CinemachineSplineRoll.
 
 
 ## [3.1.1] - 2024-06-15

com.unity.cinemachine/Documentation~/CinemachineSplineRoll.md

@@ -11,6 +11,7 @@ If you add this behavior to the Spline itself, then any [Cinemachine Camera](Cin
 | Property | Field | Description |
 | --- | --- | --- |
 | __Index Unit__ |  | Defines how to interpret the _Index_ field for each data point.  _Knot_ is the recommended value because it remains robust if the spline points change. |
+| __Easing__ |  | When enabled, roll value will ease in and out of the data point values.  Otherwise, interpolation is linear. |
 | __Data Points__ |  | The list of Roll points on the spline.  At these postions on the spline, it will take on the specified roll value. |
 | | _Index_ | The position on the Spline where it should assume the specified roll.  The value is interpreted according to the _Index Unit_ setting. |
 | | _Roll_ | The roll value for the spline.  This is specified in degrees, and the axis of rotation is the spline tangent at that point. |

com.unity.cinemachine/Editor/Editors/CinemachineSplineRollEditor.cs

@@ -37,6 +37,7 @@ public override VisualElement CreateInspectorGUI()
 
             var rollProp = serializedObject.FindProperty(() => splineData.Roll);
             ux.Add(SplineDataInspectorUtility.CreatePathUnitField(rollProp, () => splineData == null ? null : splineData.SplineContainer));
+            ux.Add(new PropertyField(serializedObject.FindProperty(() => splineData.Easing)));
 
             ux.AddHeader("Data Points");
             var list = ux.AddChild(SplineDataInspectorUtility.CreateDataListField(splineData.Roll, rollProp, () => splineData?.SplineContainer));

com.unity.cinemachine/Runtime/Behaviours/CinemachineSplineRoll.cs

@@ -42,13 +42,38 @@ public struct RollData
             public static implicit operator RollData(float roll) => new () { Value = roll };
         }
 
-        /// <summary>Interpolator for the RollData</summary>
+        /// <summary>
+        /// When enabled, roll eases into and out of the data point values
+        /// </summary>
+        [Tooltip("When enabled, roll eases into and out of the data point values.")]
+        public bool Easing = true;
+
+        /// <summary>
+        /// Get the appropriate interpolator for the RollData, depending on the Easing setting
+        /// </summary>
+        /// <returns>The appropriate interpolator for the RollData, depending on the Easing setting.</returns>
+        public IInterpolator<RollData> GetInterpolator() => Easing ? new LerpRollDataWithEasing() : new LerpRollData();
+
+        /// <summary>Interpolator for the RollData, with no easing between data points.</summary>
         public struct LerpRollData : IInterpolator<RollData>
         {
             /// <inheritdoc/>
             public RollData Interpolate(RollData a, RollData b, float t) => new() { Value = Mathf.Lerp(a.Value, b.Value, t) };
         }
 
+        /// <summary>Interpolator for the RollData, with easing between data points</summary>
+        public struct LerpRollDataWithEasing : IInterpolator<RollData>
+        {
+            /// <inheritdoc/>
+            public RollData Interpolate(RollData a, RollData b, float t) 
+            {
+                var t2 = t * t;
+                var d = 1f - t;
+                t = 3f * d * t2 + t * t2;
+                return new() { Value = Mathf.Lerp(a.Value, b.Value, t) };
+            }
+        }
+
         /// <summary>
         /// Roll (in degrees) around the forward direction for specific location on the track.
         /// When placed on a SplineContainer, this is going to be a global override that affects all vcams using the Spline.
@@ -78,6 +103,12 @@ internal ISplineContainer SplineContainer
             }
         }
 #endif
+        void Reset()
+        {
+            Roll.Clear();
+            Easing = true;
+        }
+
         void OnEnable() {} // Needed so we can disable it in the editor
 
         /// <summary>Cache for clients that use CinemachineSplineRoll</summary>

com.unity.cinemachine/Runtime/Core/SplineContainerExtensions.cs

@@ -64,8 +64,7 @@ static class SplineContainerExtensions
             // Apply extra roll
             if (roll != null && roll.enabled)
             {
-                float rollValue = roll.Roll.Evaluate(spline, tNormalized, 
-                    PathIndexUnit.Normalized, new CinemachineSplineRoll.LerpRollData());
+                float rollValue = roll.Roll.Evaluate(spline, tNormalized, PathIndexUnit.Normalized, roll.GetInterpolator());
                 rotation = Quaternion.AngleAxis(-rollValue, fwd) * rotation;
             }
             return true;