# Rotating transformation - Calculation

Hello,

In another program (which somebody else made) there is defined, how i have to rotate my 3D-Objects in my Browser-App. In that program (of somebody else) the default room coordinates are f.e. defined like:
X_X: 1
X_Y: 0 first vector
X_Z: 0

Y_X: 0
Y_Y: 1 second vector
Y_Z: 0

Z_X: 0
Z_Y: 0 third vector
Z_Z: 1

So if now an object with Three.js rotation (0,0,0) is spawning, it has the same coordinates as the normal room coordinates above.
Now i get some information, that i have to rotate my object to (just as example):

X_X: 0
X_Y: 0 first vector
X_Z: 1

Y_X: 0
Y_Y: -1 second vector
Y_Z: 0

Z_X: 1
Z_Y: 0 third vector
Z_Z: 0

Is there some easy way or function i could use to calculate values out of these vectors to set the object.rotation in my Three.js program? There should be a mathematical algorithm but i can’t find it.
Probably i need a matrix transformation or something to get an Euler out of it…

this is how you get Euler angles in radians from a 2 point vector in a 3d space

``````getEuler3D: function (pA, pB) {
// Set starting and ending vectors
var myVector = new THREE.Vector3(pA.x, pA.y, pA.z);
var targetVector = new THREE.Vector3(pB.x, pB.y, pB.z);

// Normalize vectors to make sure they have a length of 1
myVector.normalize();
targetVector.normalize();
// console.log("myVector Normalized: ", myVector);

var euler = new THREE.Euler();

if(myVector.x === targetVector.x && myVector.y === targetVector.y && myVector.z === targetVector.z ){
console.log(':. USE ioiM.getEuler2D - Both Vectors have the same Normal.');
} else {
// Create a quaternion, and apply starting, then ending vectors
var quaternion = new THREE.Quaternion();
quaternion.setFromUnitVectors(myVector, targetVector);
//console.log("quaternion ", quaternion);

// Quaternion now has rotation data within it.
// We'll need to get it out with a THREE.Euler()
// var euler = new THREE.Euler();
euler.setFromQuaternion(quaternion);
//console.log(euler.toArray());

return euler;
}
// Resulting euler will have x, y, z rotations in radians:
//[
//  0: -1.6704649792860586,
//  1: 0.09917726107940236,
//  2: 0.10956980436233299,
//  3: "XYZ"
//]
},``````
1 Like

Ok, i am not sure if i can transform my 9 vectors in 2… Is this correct?:
First picture vector (1,1,1) and the second picture vector (1,-1,1).
Will this get me the rotation i need?

Btw. another question: I can rotate my object around the center of my geometry with “geometry.center()”.
Is there an option to rotate the object around a point inside the object?

that i do not know, i tought you were looking to find Euler angles from an vector