Merge pull request opentk#1772 from NogginBops/slerp-docs

Document that slerping between vectors of opposite direction is undefined.

Author: NogginBops

src/OpenTK.Mathematics/Vector/Vector3.cs

@@ -814,6 +814,7 @@ public static void Lerp(in Vector3 a, in Vector3 b, Vector3 blend, out Vector3 r
         /// <summary>
         /// Returns a new vector that is the spherical interpolation of the two given vectors.
         /// <paramref name="a"/> and <paramref name="b"/> need to be normalized for this function to work properly.
+        /// Results are undefined for vectors that point in opposite directions or very close to opposite directions.
         /// </summary>
         /// <param name="a">Unit vector start point.</param>
         /// <param name="b">Unit vector end point.</param>
@@ -844,6 +845,7 @@ public static Vector3 Slerp(Vector3 a, Vector3 b, float t)
         /// <summary>
         /// Returns a new vector that is the spherical interpolation of the two given vectors.
         /// <paramref name="a"/> and <paramref name="b"/> need to be normalized for this function to work properly.
+        /// Results are undefined for vectors that point in opposite directions or very close to opposite directions.
         /// </summary>
         /// <param name="a">Unit vector start point.</param>
         /// <param name="b">Unit vector end point.</param>

src/OpenTK.Mathematics/Vector/Vector3d.cs

@@ -808,6 +808,7 @@ public static void Lerp(in Vector3d a, in Vector3d b, Vector3d blend, out Vector
         /// <summary>
         /// Returns a new vector that is the spherical interpolation of the two given vectors.
         /// <paramref name="a"/> and <paramref name="b"/> need to be normalized for this function to work properly.
+        /// Results are undefined for vectors that point in opposite directions or very close to opposite directions.
         /// </summary>
         /// <param name="a">Unit vector start point.</param>
         /// <param name="b">Unit vector end point.</param>
@@ -838,6 +839,7 @@ public static Vector3d Slerp(Vector3d a, Vector3d b, double t)
         /// <summary>
         /// Returns a new vector that is the spherical interpolation of the two given vectors.
         /// <paramref name="a"/> and <paramref name="b"/> need to be normalized for this function to work properly.
+        /// Results are undefined for vectors that point in opposite directions or very close to opposite directions.
         /// </summary>
         /// <param name="a">Unit vector start point.</param>
         /// <param name="b">Unit vector end point.</param>

src/OpenTK.Mathematics/Vector/Vector4.cs

@@ -804,6 +804,7 @@ public static void Lerp(in Vector4 a, in Vector4 b, Vector4 blend, out Vector4 r
         /// <summary>
         /// Returns a new vector that is the spherical interpolation of the two given vectors.
         /// <paramref name="a"/> and <paramref name="b"/> need to be normalized for this function to work properly.
+        /// Results are undefined for vectors that point in opposite directions or very close to opposite directions.
         /// </summary>
         /// <param name="a">Unit vector start point.</param>
         /// <param name="b">Unit vector end point.</param>
@@ -834,6 +835,7 @@ public static Vector4 Slerp(Vector4 a, Vector4 b, float t)
         /// <summary>
         /// Returns a new vector that is the spherical interpolation of the two given vectors.
         /// <paramref name="a"/> and <paramref name="b"/> need to be normalized for this function to work properly.
+        /// Results are undefined for vectors that point in opposite directions or very close to opposite directions.
         /// </summary>
         /// <param name="a">Unit vector start point.</param>
         /// <param name="b">Unit vector end point.</param>

src/OpenTK.Mathematics/Vector/Vector4d.cs

@@ -799,6 +799,7 @@ public static void Lerp(in Vector4d a, in Vector4d b, Vector4d blend, out Vector
         /// <summary>
         /// Returns a new vector that is the spherical interpolation of the two given vectors.
         /// <paramref name="a"/> and <paramref name="b"/> need to be normalized for this function to work properly.
+        /// Results are undefined for vectors that point in opposite directions or very close to opposite directions.
         /// </summary>
         /// <param name="a">Unit vector start point.</param>
         /// <param name="b">Unit vector end point.</param>
@@ -829,6 +830,7 @@ public static Vector4d Slerp(Vector4d a, Vector4d b, double t)
         /// <summary>
         /// Returns a new vector that is the spherical interpolation of the two given vectors.
         /// <paramref name="a"/> and <paramref name="b"/> need to be normalized for this function to work properly.
+        /// Results are undefined for vectors that point in opposite directions or very close to opposite directions.
         /// </summary>
         /// <param name="a">Unit vector start point.</param>
         /// <param name="b">Unit vector end point.</param>