Unity 利用Quaternion.LookRotation API 将旋转矩阵转换成四元数

Quaternion.LookRotation

 

private static
Quaternion QuaternionLookRotation(Vector3 forward,
Vector3 up)
{
    forward.Normalize();

    Vector3 vector
= Vector3.Normalize(forward);
    Vector3 vector2
= Vector3.Normalize(Vector3.Cross(up,
vector));
    Vector3 vector3
= Vector3.Cross(vector, vector2);
    var m00
= vector2.x;
    var m01
= vector2.y;
    var m02
= vector2.z;
    var m10
= vector3.x;
    var m11
= vector3.y;
    var m12
= vector3.z;
    var m20
= vector.x;
    var m21
= vector.y;
    var m22
= vector.z;

    float num8
= (m00
+ m11)
+ m22;
    var quaternion
= new
Quaternion();
    if
(num8 >
0f)
    {
        var num
= (float)Math.Sqrt(num8
+ 1f);
        quaternion.w
= num *
0.5f;
        num =
0.5f / num;
        quaternion.x
= (m12
- m21)
* num;
        quaternion.y
= (m20
- m02)
* num;
        quaternion.z
= (m01
- m10)
* num;
        return quaternion;
    }
    if
((m00 >= m11)
&& (m00
>= m22))
    {
        var num7
= (float)Math.Sqrt(((1f
+ m00)
- m11)
- m22);
        var num4
= 0.5f
/ num7;
        quaternion.x
= 0.5f
* num7;
        quaternion.y
= (m01
+ m10)
* num4;
        quaternion.z
= (m02
+ m20)
* num4;
        quaternion.w
= (m12
- m21)
* num4;
        return quaternion;
    }
    if
(m11 > m22)
    {
        var num6
= (float)Math.Sqrt(((1f
+ m11)
- m00)
- m22);
        var num3
= 0.5f
/ num6;
        quaternion.x
= (m10+ m01)
* num3;
        quaternion.y
= 0.5f
* num6;
        quaternion.z
= (m21
+ m12)
* num3;
        quaternion.w
= (m20
- m02)
* num3;
        return quaternion;

    }
    var num5
= (float)Math.Sqrt(((1f
+ m22)
- m00)
- m11);
    var num2
= 0.5f
/ num5;
    quaternion.x
= (m20
+ m02)
* num2;
    quaternion.y
= (m21
+ m12)
* num2;
    quaternion.z
= 0.5f
* num5;
    quaternion.w
= (m01
- m10)
* num2;
    return quaternion;
}