Function stMtx2Qt

src/Sato/stMath.cpp:271–326

TODO: match it in a way that makes sense https://decomp.me/scratch/2u8r1

// TODO: match it in a way that makes sense
// https://decomp.me/scratch/2u8r1
void stMtx2Qt(Quaternion *q, const Mtx m)
{
    f32 x = m[0][0];
    f32 y = m[1][1];
    f32 z = m[2][2];
    f32 length = x + y + z;
    if (length > 0.0f)
    {
        length = std::sqrtf(1.0f + length);
        f32 t = 0.5f / length;
        q->w = 0.5f * length;
        q->x = t * (m[2][1] - m[1][2]);
        q->y = t * (m[0][2] - m[2][0]);
        q->z = t * (m[1][0] - m[0][1]);
    }
    else
    {
        f32 direction = x;
        if (y > x)
        {
            direction = m[1][1];
        }
        else if (z > x)
        {
            direction = m[2][2];
        }

        if (direction == x)
        {
            x = stspeedy_sqrtf(1.0f + (x - (y + z)));
            f32 t = 0.5f / x;
            q->x = 0.5f * x;
            q->y = t * (m[0][1] + m[1][0]);
            q->z = t * (m[2][0] + m[0][2]);
            q->w = t * (m[2][1] - m[1][2]);
        }
        else if (direction == y)
        {
            x = stspeedy_sqrtf(1.0f + (y - (z + x)));
            f32 t = 0.5f / x;
            q->y = 0.5f * x;
            q->z = t * (m[1][2] + m[2][1]);
            q->x = t * (m[0][1] + m[1][0]);
            q->w = t * (m[0][2] - m[2][0]);
        }
        else
        {
            x = stspeedy_sqrtf(1.0f + (z - (x + y)));
            f32 t = 0.5f / x;
            q->z = 0.5f * x;
            q->x = t * (m[2][0] + m[0][2]);
            q->y = t * (m[1][2] + m[2][1]);
            q->w = t * (m[1][0] - m[0][1]);
        }
    }
}

void stQtLerp(Quaternion *dst, const Quaternion *p, const Quaternion *q, float t)