Issue with makeRotationFromQuaternion

Hello,

I believe the function makeRotationFromQuaternion gives incorrect results.

The R function below returns a rotation matrix which transforms U to V.

getRotation <- function(U,V){
  ma <- sqrt(c(crossprod(U)))
  mb <- sqrt(c(crossprod(V))) # ?? no sense if ma /= mb ...
  d <- c(tcrossprod(U, t(V)))
  c <- sqrt(ma*mb+d)
  ma2 <- sqrt(2)*ma
  r <- 1/ma2/c
  W <- crossProduct(U,V)
  q <- c(c/ma2, r*W)
  quaternion2matrix(q) 
}

I have tested it and it works.

The Javascript version:

function getRotation(U, V) {
    var ma = U.length();
    var mb = V.length(); // should be = ma
    var d = U.x * V.x + U.y * V.y + U.z * V.z;
    var c = Math.sqrt(ma * mb + d);
    var ma2 = Math.sqrt(2) * ma;
    var r = 1 / ma2 / c;
    var W = U.clone().cross(V).multiplyScalar(r);
    var quat = new THREE.Quaternion().set(c / ma2, W.x, W.y, W.z);
    return new THREE.Matrix4().makeRotationFromQuaternion(quat);
}

Test:

var u = new THREE.Vector3(1,0,0);
var v = new THREE.Vector3(1,2,3).normalize();
var R = getRotation(u,v).transpose().elements;
console.log(R[0] * u.x + R[1] * u.y + R[2] * u.z); // should be v.x, found 0.492719
console.log(R[4] * u.x + R[5] * u.y + R[6] * u.z); // should be v.y, found -0.33818
console.log(R[8] * u.x + R[9] * u.y + R[10] * u.z); // should be v.z, found -0.80178

The matricial product R*u should give v, but it does not.

[stla]

Yeah, that’s right. The order is not the same and you were right, in three.js we have to do: var quat = new THREE.Quaternion().set(W.x, W.y, W.z, c / ma2); And everything works fine! Sorry!

[stla]

Wait, I see what you meant… My quaternions in R and the three.js quaternions do not use the same order, perhaps. I check…