quat
quat_slerp(const quat *q1, const quat *q2, float t)
{
float cos_theta = quat_dot(q1, q2);
float theta = acos(cos_theta);
float sin_theta = sin(theta);
if (sin_theta > 0.001f) {
float w1 = sin( (1.f-t) * theta) / sin_theta;
float w2 = sin(t * theta) / sin_theta;
quat q3, q4;
q3 = quat_scale(q1, w1);
q4 = quat_scale(q2, w2);
return quat_add(&q3, &q4);
} else {
return quat_lerp(q1, q2, t);
}
}
union quat *quat_nlerp(union quat *qo, const union quat *qfrom, const union quat *qto, float t)
{
quat_lerp(qo, qfrom, qto, t);
quat_normalize_self(qo);
return qo;
}
