Eular and Quaternion

eular-quaternion.js

function ToQuaternion(yaw, pitch,  roll) // yaw (Z), pitch (Y), roll (X)
{
    // Abbreviations for the various angular functions
    let cy = Math.cos(yaw * 0.5);
    let sy = Math.sin(yaw * 0.5);
    let cp = Math.cos(pitch * 0.5);
    let sp = Math.sin(pitch * 0.5);
    let cr = Math.cos(roll * 0.5);
    let sr = Math.sin(roll * 0.5);

    let q = {};
    q.w = cr * cp * cy + sr * sp * sy;
    q.x = sr * cp * cy - cr * sp * sy;
    q.y = cr * sp * cy + sr * cp * sy;
    q.z = cr * cp * sy - sr * sp * cy;

    return q;
}

function ToEulerAngles(q) {
    let angles = {};

    // roll (x-axis rotation)
    let sinr_cosp = 2 * (q.w * q.x + q.y * q.z);
    let cosr_cosp = 1 - 2 * (q.x * q.x + q.y * q.y);
    angles.roll = Math.atan2(sinr_cosp, cosr_cosp);

    // pitch (y-axis rotation)
    let sinp = 2 * (q.w * q.y - q.z * q.x);
    if (Math.abs(sinp) >= 1) {
        angles.pitch = sinp>0 ? Math.PI/2 : -Math.PI/2; // use 90 degrees if out of range
    }
    else {
        angles.pitch = Math.asin(sinp);
    }

    // yaw (z-axis rotation)
    let siny_cosp = 2 * (q.w * q.z + q.x * q.y);
    let cosy_cosp = 1 - 2 * (q.y * q.y + q.z * q.z);
    angles.yaw = Math.atan2(siny_cosp, cosy_cosp);

    return angles;
}