public static QuaternionF Slerp(QuaternionF start, QuaternionF end, float blend)
{
// Clone to avoid modifying the parameters
var q1 = start.Clone();
var q2 = end.Clone();
// if either input is zero, return the other.
if (Math.Abs(q1.Magnitude() - 0) < 0.0001)
{
return(Math.Abs(q2.Magnitude() - 0) < 0.0001 ? Identity : q2);
}
if (Math.Abs(q2.Magnitude() - 0) < 0.0001)
{
return(q1);
}
var cosHalfAngle = q1.Dot(q2);
if (cosHalfAngle >= 1 || cosHalfAngle <= -1)
{
return(q1);
}
if (cosHalfAngle < 0)
{
q2.Vector = -q2.Vector;
q2.Scalar = -q2.Scalar;
cosHalfAngle = -cosHalfAngle;
}
float blendA;
float blendB;
if (cosHalfAngle < 0.99)
{
// do proper slerp for big angles
var halfAngle = (float)Math.Acos(cosHalfAngle);
var sinHalfAngle = (float)Math.Sin(halfAngle);
var oneOverSinHalfAngle = 1 / sinHalfAngle;
blendA = (float)Math.Sin(halfAngle * (1 - blend)) * oneOverSinHalfAngle;
blendB = (float)Math.Sin(halfAngle * blend) * oneOverSinHalfAngle;
}
else
{
// do lerp if angle is really small.
blendA = 1 - blend;
blendB = blend;
}
var result = new QuaternionF(blendA * q1.Vector + blendB * q2.Vector, blendA * q1.W + blendB * q2.W);
return(result.Magnitude() > 0 ? result.Normalise() : Identity);
}
public static QuaternionF Lerp(QuaternionF start, QuaternionF end, float blend)
{
// Clone to avoid modifying the parameters
var q1 = start.Clone();
var q2 = end.Clone();
// if either input is zero, return the other.
if (Math.Abs(q1.Magnitude() - 0) < 0.0001)
{
return(Math.Abs(q2.Magnitude() - 0) < 0.0001 ? Identity : q2);
}
if (Math.Abs(q2.Magnitude() - 0) < 0.0001)
{
return(q1);
}
var blendA = 1 - blend;
var blendB = blend;
var result = new QuaternionF(blendA * q1.Vector + blendB * q2.Vector, blendA * q1.W + blendB * q2.W);
return(result.Magnitude() > 0 ? result.Normalise() : Identity);
}