//
//#############################################################################
//#############################################################################
//
Scalar
UnitQuaternion::GetAngle()
{
Check_Object(this);
Scalar sine_of_half = Sqrt(x*x + y*y + z*z);
if (Small_Enough(sine_of_half))
{
return 0.0f;
}
SinCosPair half_angle(sine_of_half, w);
Radian angle;
angle = half_angle;
return angle * 2.0f;
}
//
//#############################################################################
//#############################################################################
//
UnitQuaternion&
UnitQuaternion::Multiply(
const UnitQuaternion &q,
Scalar t
)
{
Check_Pointer(this);
Check_Object(&q);
//
//---------------------------------------------------------
// Figure out the half the angle of rotation and scale that
//---------------------------------------------------------
//
Scalar sine_of_half = Sqrt(q.x*q.x + q.y*q.y + q.z*q.z);
if (Small_Enough(sine_of_half))
{
*this = Identity;
return *this;
}
SinCosPair half_angle(sine_of_half, q.w);
Radian angle;
angle = half_angle;
angle *= t;
half_angle = angle;
//
//-----------------------------------------------------------------
// Build the scaled quaternion out of the components of the old one
//-----------------------------------------------------------------
//
w = half_angle.cosine;
sine_of_half = half_angle.sine / sine_of_half;
x = q.x * sine_of_half;
y = q.y * sine_of_half;
z = q.z * sine_of_half;
Check_Object(this);
return *this;
}
//
//###########################################################################
//###########################################################################
//
Vector3D&
Vector3D::operator=(const UnitQuaternion &q)
{
Check_Pointer(this);
Check_Object(&q);
Scalar sine_of_half = Sqrt(q.x*q.x + q.y*q.y + q.z*q.z);
if (Small_Enough(sine_of_half))
{
return *this = Identity;
}
SinCosPair half_angle(sine_of_half, q.w);
Radian angle;
angle = half_angle;
Scalar len = angle * 2.0f / sine_of_half;
x = q.x * len;
y = q.y * len;
z = q.z * len;
return *this;
}
