/// <summary>
/// Performs interpolation between two quaternions using spherical linear interpolation.
/// </summary>
/// <param name="a">Quaternion</param>
/// <param name="b">Quaternion</param>
/// <param name="amount">Relative weight of the second quaternion in interpolation</param>
/// <returns>Quaternion</returns>
public static Quaternion32 Slerp(Quaternion32 a, Quaternion32 b, float amount)
{
float d, e, dot = Quaternion32.Dot(a, b);
bool flag = false;
if (dot < 0.0)
{
flag = true;
dot = -dot;
}
if (dot > 0.999999)
{
d = 1.0f - amount;
e = (flag ? (-amount) : amount);
}
else
{
float f = (float)Math.Acos(dot);
float g = (float)(1.0 / Math.Sin(f));
d = (float)Math.Sin(((1.0 - amount) * f)) * g;
e = (float)(flag ? ((-Math.Sin((amount * f))) * g) : (Math.Sin((amount * f)) * g));
}
return(new Quaternion32(
d * a.X + e * b.X,
d * a.Y + e * b.Y,
d * a.Z + e * b.Z,
d * a.W + e * b.W));
}
/// <summary>
/// Performs linear interpolation between two quaternions based on a value indicating the weighting of the second quaternion.
/// </summary>
/// <param name="a">Quaternion</param>
/// <param name="b">Quaternion</param>
/// <param name="amount">Relative weight of the second quaternion in interpolation</param>
/// <returns>Quaternion</returns>
public static Quaternion32 Lerp(Quaternion32 a, Quaternion32 b, float amount)
{
float f = 1.0f - amount;
Quaternion32 quaternion3 = default(Quaternion32);
float dot = Dot(a, b);
if (dot >= 0.0)
{
quaternion3.X = f * a.X + amount * b.X;
quaternion3.Y = f * a.Y + amount * b.Y;
quaternion3.Z = f * a.Z + amount * b.Z;
quaternion3.W = f * a.W + amount * b.W;
}
else
{
quaternion3.X = f * a.X - amount * b.X;
quaternion3.Y = f * a.Y - amount * b.Y;
quaternion3.Z = f * a.Z - amount * b.Z;
quaternion3.W = f * a.W - amount * b.W;
}
float norm = 1.0f / quaternion3.Abs;
quaternion3.X *= norm;
quaternion3.Y *= norm;
quaternion3.Z *= norm;
quaternion3.W *= norm;
return(quaternion3);
}
/// <summary>
/// Tries to parse the string into Quaternion.
/// </summary>
/// <param name="quaternion">Input string</param>
/// <param name="result">Quaternion</param>
/// <returns>Boolean</returns>
public static bool TryParse(string quaternion, ref Quaternion32 result)
{
try
{
result = Quaternion32.Parse(quaternion);
return(true);
}
catch (FormatException)
{
result = new Quaternion32();
return(false);
}
}
/// <summary>
/// Concatenates two quaternions.
/// </summary>
/// <param name="a">Quaternion</param>
/// <param name="b">Quaternion</param>
/// <returns>Quaternion</returns>
public static Quaternion32 Concatenate(Quaternion32 a, Quaternion32 b)
{
float x = b.X, y = b.Y, z = b.Z, w = b.W;
float x2 = a.X, y2 = a.Y, z2 = a.Z, w2 = a.W;
float e = y * z2 - z * y2;
float f = z * x2 - x * z2;
float c = x * y2 - y * x2;
float d = x * x2 + y * y2 + z * z2;
return(new Quaternion32(
x * w2 + x2 * w + e,
y * w2 + y2 * w + f,
z * w2 + z2 * w + c,
w * w2 - d));
}
/// <summary>
/// Computes the scalar product of two quaternion.
/// </summary>
/// <param name="a">Quaternion</param>
/// <param name="b">Quaternion</param>
/// <returns>Quaternion</returns>
public static float Dot(Quaternion32 a, Quaternion32 b)
{
return(a.X * b.X + a.Y * b.Y + a.Z * b.Z + a.W * b.W);
}
