FromToRotation working or not working?

[winxalex]

Not sure if I'm using correctly or there is some aprox bug.
Funciton works for rest of angles(vectors are in XZ plane), but when need to rotate from x=-0.9999999 to x=0.9999999 (z same in both 4.222,y=0) rotation gives me 180 rotation around Z instead of Y.

`function orthogonal(v) {

var x = Math.abs(v.x);

var y = Math.abs(v.y);

var z = Math.abs(v.z);

var other = x < y ? ( x < z ? pc.Vec3.RIGHT : pc.Vec3.FORWARD ) : ( y < z ? pc.Vec3.UP : pc.Vec3.FORWARD );

return new pc.Vec3().cross(v, other);

}

pc.Vec3.prototype.orthogonal = function() {

return orthogonal(this);

};

function fromToRotation(v1, v2, q) {

var kct = v1.dot(v2);

q = q || Q();

if (kct <= -0.999) {

    q.w = 0;

    var v = orthogonal(v1).normalize();

    q.x = v.x;

    q.y = v.y;

    q.z = v.z;

    return q;

}

//var half = V(v1).add(v2).scale(0.5);
//
var half = new pc.Vec3().copy(v1).add(v2).scale(0.5);

q.w = v1.dot(half);

var cross = new pc.Vec3().cross(v1, half);

q.x = cross.x;

q.y = cross.y;

q.z = cross.z;

return q.normalize();

}`

[winxalex]

I can confirm there is approximation error. For example if v1==-v2, kct check fail I for example have got -0.94,...so following this link https://stackoverflow.com/questions/1171849/finding-quaternion-representing-the-rotation-from-one-vector-to-another I'm checking for

` var k= Math.sqrt(v1.lengthSq() * v2.lengthSq());

// if (kct <= -0.999) { //doesn't work when v1=-v2
// if (kct <= -0.97) {
if (kct / k == -1){
q.w = 0;

    var v = orthogonal(v1).normalize();

    q.x = v.x;

    q.y = v.y;

    q.z = v.z;

    return q;

}` 

but code can be probably even more optimized compared to half solution???