public static Quaternion FromMatrix(Matrix4 m1)
{
float w = (float)System.Math.Sqrt(System.Math.Max(0, 1 + m1.M11 + m1.M22 + m1.M33)) / 2f;
float x = (float)System.Math.Sqrt(System.Math.Max(0, 1 + m1.M11 - m1.M22 - m1.M33)) / 2f;
float y = (float)System.Math.Sqrt(System.Math.Max(0, 1 - m1.M11 + m1.M22 - m1.M33)) / 2f;
float z = (float)System.Math.Sqrt(System.Math.Max(0, 1 - m1.M11 - m1.M22 + m1.M33)) / 2f;
x = FloatHelper.CopySign(x, m1.M32 - m1.M23);
y = FloatHelper.CopySign(y, m1.M12 - m1.M31);
z = FloatHelper.CopySign(z, m1.M21 - m1.M12);
return(new Quaternion(x, y, z, w));
}
public static Quaternion FromMatrix(Matrix4 m1)
{
// if (false)
// {
// float w = (float)Math.Sqrt(1.0 + m1.M11 + m1.M22 + m1.M33) / 2.0f;
// float w4 = (4.0f * w);
// float x = (m1.M32 - m1.M23) / w4;
// float y = (m1.M13 - m1.M31) / w4;
// float z = (m1.M21 - m1.M12) / w4;
//
// return new Quaternion(x, y, z, w);
// }
float w = (float)System.Math.Sqrt(System.Math.Max(0, 1 + m1.M11 + m1.M22 + m1.M33)) / 2f;
float x = (float)System.Math.Sqrt(System.Math.Max(0, 1 + m1.M11 - m1.M22 - m1.M33)) / 2f;
float y = (float)System.Math.Sqrt(System.Math.Max(0, 1 - m1.M11 + m1.M22 - m1.M33)) / 2f;
float z = (float)System.Math.Sqrt(System.Math.Max(0, 1 - m1.M11 - m1.M22 + m1.M33)) / 2f;
x = FloatHelper.CopySign(x, m1.M32 - m1.M23);
y = FloatHelper.CopySign(y, m1.M12 - m1.M31);
z = FloatHelper.CopySign(z, m1.M21 - m1.M12);
return(new Quaternion(x, y, z, w));
}
