//Ethan Alexander Shulman 2019
//Converts OpenVR rotation matrix to quaternion with coordinate system +x,+y,+z
void mat2quat(HmdMatrix34_t m, float *q) {
    float rt = m.m[0][0] + m.m[1][1] + m.m[2][2];
    if (rt > 0.0f) {
        const float s = sqrtf(rt + 1.0f), b = 0.5f / s;
        q[0] = (m.m[1][2]-m.m[2][1])*b;
        q[1] = (m.m[2][0] - m.m[0][2])*b;
        q[2] = (m.m[0][1] - m.m[1][0])*-b;
        q[3] = s*0.5f;
    }
    else if (m.m[0][0] > m.m[1][1] && m.m[0][0] > m.m[2][2]) {
        const float s = sqrtf(1.0f + m.m[0][0] - m.m[1][1] - m.m[2][2]), b = 0.5f / s;
        q[0] = s*0.5f;
        q[1] = (m.m[1][0] + m.m[0][1])*b;
        q[2] = (m.m[2][0] + m.m[0][2])*-b;
        q[3] = (m.m[1][2] - m.m[2][1])*b;
    }
    else if (m.m[1][1] > m.m[2][2]) {
        const float s = sqrtf(1.0f + m.m[1][1] - m.m[0][0] - m.m[2][2]), b = 0.5f / s;
        q[0] = (m.m[0][1] + m.m[1][0])*b;
        q[1] = s*0.5f;
        q[2] = (m.m[1][2] + m.m[2][1])*-b;
        q[3] = (m.m[0][2] - m.m[2][0])*-b;
    } else {
        const float s = sqrtf(1.0f + m.m[2][2] - m.m[0][0] - m.m[1][1]), b = 0.5f / s;
        q[0] = (m.m[0][2] + m.m[2][0])*-b;
        q[1] = (m.m[1][2] + m.m[2][1])*-b;
        q[2] = s*0.5f;
        q[3] = (m.m[1][0] - m.m[0][1])*b;
    }
}
```