/// <summary>
/// Convert this instance to an axis-angle representation.
/// </summary>
/// <returns>A Vector4 that is the axis-angle representation of this quaternion.</returns>
public GVector4 ToAxisAngle()
{
var q = this;
if (Math.Abs(q.W) > 1.0f)
{
q.Normalize();
}
GVector4 result = new GVector4();
result.W = 2.0f * (float)System.Math.Acos(q.W); // angle
float den = (float)System.Math.Sqrt(1.0 - q.W * q.W);
if (den > 0.0001f)
{
result.Xyz = q.Xyz / den;
}
else
{
// This occurs when the angle is zero.
// Not a problem: just set an arbitrary normalized axis.
result.Xyz = GVector3.UnitX;
}
return(result);
}
/// <summary>
/// Convert the current quaternion to axis angle representation
/// </summary>
/// <param name="axis">The resultant axis</param>
/// <param name="angle">The resultant angle</param>
public void ToAxisAngle(out GVector3 axis, out float angle)
{
GVector4 result = ToAxisAngle();
axis = result.Xyz;
angle = result.W;
}
/// <summary>Transform a Vector3 by the given Matrix, and project the resulting Vector4 back to a Vector3</summary>
/// <param name="vec">The vector to transform</param>
/// <param name="mat">The desired transformation</param>
/// <param name="result">The transformed vector</param>
public static void TransformPerspective(ref GVector3 vec, ref Matrix4 mat, out GVector3 result)
{
GVector4 v = new GVector4(vec, 1);
GVector4.Transform(ref v, ref mat, out v);
result.x = v.X / v.W;
result.y = v.Y / v.W;
result.z = v.Z / v.W;
}
public GVector3(GVector4 src)
{
this.x = src.X;
this.y = src.Y;
this.z = src.Z;
}
