setMatrixAt( instanceId, matrix ) {

		this.validateInstanceId( instanceId );

		const matricesTexture = this._matricesTexture;
		const matricesArray = this._matricesTexture.image.data;
		matrix.toArray( matricesArray, instanceId * 16 );
		matricesTexture.needsUpdate = true;

		return this;

	}
Sets the given local transformation matrix to the defined instance.
Negatively scaled matrices are not supported.

@param {number} instanceId - The ID of an instance to set the matrix of.
@param {Matrix4} matrix - A 4x4 matrix representing the local transformation of a single instance.
@return {BatchedMesh} A reference to this batched mesh.