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@hb3p8
Created Mar 11, 2015
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Spherical linear interpolation between unit quaternions q1 and q2 with interpolation parameter t.
// Spherical linear interpolation between unit quaternions q1 and q2 with interpolation parameter t.
Quaternion slerp(Quaternion q1, Quaternion q2, float t)
{
float w1, x1, y1, z1, w2, x2, y2, z2, w3, x3, y3, z3;
Quaternion q2New;
float theta, mult1, mult2;
w1 = q1.getW(); x1 = q1.getX(); y1 = q1.getY(); z1 = q1.getZ();
w2 = q2.getW(); x2 = q2.getX(); y2 = q2.getY(); z2 = q2.getZ();
// Reverse the sign of q2 if q1.q2 < 0.
if (w1*w2 + x1*x2 + y1*y2 + z1*z2 < 0)
{
w2 = -w2; x2 = -x2; y2 = -y2; z2 = -z2;
}
theta = acos(w1*w2 + x1*x2 + y1*y2 + z1*z2);
if (theta > 0.000001)
{
mult1 = sin( (1-t)*theta ) / sin( theta );
mult2 = sin( t*theta ) / sin( theta );
}
// To avoid division by 0 and by very small numbers the approximation of sin(angle)
// by angle is used when theta is small (0.000001 is chosen arbitrarily).
else
{
mult1 = 1 - t;
mult2 = t;
}
w3 = mult1*w1 + mult2*w2;
x3 = mult1*x1 + mult2*x2;
y3 = mult1*y1 + mult2*y2;
z3 = mult1*z1 + mult2*z2;
return *new Quaternion(w3, x3, y3, z3);
}
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