gl-rocket/glm/ext/quaternion_exponential.inl
Artur Tamborski 0189b137f7 i d
2021-01-02 17:01:54 +01:00

70 lines
2.1 KiB
C++

namespace glm
{
template<typename T, qualifier Q>
GLM_FUNC_QUALIFIER qua<T, Q> exp(qua<T, Q> const& q)
{
vec<3, T, Q> u(q.x, q.y, q.z);
T const Angle = glm::length(u);
if (Angle < epsilon<T>())
return qua<T, Q>();
vec<3, T, Q> const v(u / Angle);
return qua<T, Q>(cos(Angle), sin(Angle) * v);
}
template<typename T, qualifier Q>
GLM_FUNC_QUALIFIER qua<T, Q> log(qua<T, Q> const& q)
{
vec<3, T, Q> u(q.x, q.y, q.z);
T Vec3Len = length(u);
if (Vec3Len < epsilon<T>())
{
if(q.w > static_cast<T>(0))
return qua<T, Q>(log(q.w), static_cast<T>(0), static_cast<T>(0), static_cast<T>(0));
else if(q.w < static_cast<T>(0))
return qua<T, Q>(log(-q.w), pi<T>(), static_cast<T>(0), static_cast<T>(0));
else
return qua<T, Q>(std::numeric_limits<T>::infinity(), std::numeric_limits<T>::infinity(), std::numeric_limits<T>::infinity(), std::numeric_limits<T>::infinity());
}
else
{
T t = atan(Vec3Len, T(q.w)) / Vec3Len;
T QuatLen2 = Vec3Len * Vec3Len + q.w * q.w;
return qua<T, Q>(static_cast<T>(0.5) * log(QuatLen2), t * q.x, t * q.y, t * q.z);
}
}
template<typename T, qualifier Q>
GLM_FUNC_QUALIFIER qua<T, Q> pow(qua<T, Q> const& x, T y)
{
//Raising to the power of 0 should yield 1
//Needed to prevent a division by 0 error later on
if(y > -epsilon<T>() && y < epsilon<T>())
return qua<T, Q>(1,0,0,0);
//To deal with non-unit quaternions
T magnitude = sqrt(x.x * x.x + x.y * x.y + x.z * x.z + x.w *x.w);
//Equivalent to raising a real number to a power
//Needed to prevent a division by 0 error later on
if(abs(x.w / magnitude) > static_cast<T>(1) - epsilon<T>() && abs(x.w / magnitude) < static_cast<T>(1) + epsilon<T>())
return qua<T, Q>(pow(x.w, y), 0, 0, 0);
T Angle = acos(x.w / magnitude);
T NewAngle = Angle * y;
T Div = sin(NewAngle) / sin(Angle);
T Mag = pow(magnitude, y - static_cast<T>(1));
return qua<T, Q>(cos(NewAngle) * magnitude * Mag, x.x * Div * Mag, x.y * Div * Mag, x.z * Div * Mag);
}
template<typename T, qualifier Q>
GLM_FUNC_QUALIFIER qua<T, Q> sqrt(qua<T, Q> const& x)
{
return pow(x, static_cast<T>(0.5));
}
}//namespace glm