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Three.js uses *matrices* to encode 3D transformations---translations (position), rotations, and scaling. Every instance of [page:Object3D] has a [page:Object3D.matrix matrix] which stores that object's position, rotation, and scale. This page describes how to update an object's transformation.

Convenience properties and *matrixAutoUpdate*

There are two ways to update an object's transformation:
  1. Modify the object's *position*, *quaternion*, and *scale* properties, then ask Three.js to recompute the object's matrix from these properties: object.position = start_position; object.quaternion = quaternion; object.updateMatrix(); Calling the *updateMatrix* method forces the object's matrix to be recomputed from *position*, *quaternion*, and *scale*. You can also set object.matrixAutoUpdate = true; in lieu of calling *updateMatrix*. This will force the matrix to be recomputed every frame; for static objects, you should therefore set object.matrixAutoUpdate = false;
  2. Modify the object's matrix directly. The [page:Matrix4] class has various methods for modifying the matrix: object.matrix.setRotationFromQuaternion(quaternion); object.matrix.setPosition(start_position); object.matrixAutoUpdate = false; Note that *matrixAutoUpdate* must be set to *false* in this case, and you should make sure not to call *updateMatrix*. Calling *updateMatrix* will clobber the manual changes made to the matrix, recalculating the matrix from *position*, *scale*, and so on.

Object and world matrices

An object's [page:Object3D.matrix matrix] stores the object's transformation relative to the object's [page:Object3D.parent parent]; to get the object's transformation in world coordinates, you must access the object's [page:Object3D.matrixWorld].

When either the parent or the child object's transformation changes, you can request that the child object's [page:Object3D.matrixWorld matrixWorld] be updated by calling [page:Object3D.updateMatrixWorld updateMatrixWorld]().

Rotation and Quaternion

Three.js provides two ways of representing 3D rotations: [page:Euler Euler angles] and [page:Quaternion Quaternions], as well as methods for converting between the two. Euler angles are subject to a problem called "gimbal lock," where certain configurations can lose a degree of freedom (preventing the object from being rotated about one axis). For this reason, object rotations are always stored in the object's [page:Object3D.quaternion quaternion].

Previous versions of the library included a *useQuaternion* property which, when set to false, would cause the object's [page:Object3D.matrix matrix] to be calculated from an Euler angle. This practice is deprecated---instead, you should use the [page:Object3D.setRotationFromEuler setRotationFromEuler] method, which will update the quaternion.