クォータニオン（四元数）のメモ ref: http://qiita.com/edo_m18/items/5cbedcea95fef82161b2

file0.txt

function makeQuaternion(radian, vector) {
    var ret = new Quaternion(),
        ccc = 0,
        sss = 0,
        axis = new Vector3(vector.toArray()),
        norm = vector.norm();

    if (norm <= 0.0) {
        return ret;
    }

    axis.normalize();

    //cos(θ/2)
    ccc = cos(0.5 * radian);

    //sin(θ/2)
    sss = sin(0.5 * radian);

    var t = ccc; //実部
    axis.multiplyScalar(sss); //虚部

    //計算した値をQuaternionにセット
    ret.set(t, axis);

    return ret;
}