Just add the outlineMesh
as a child of the target mesh
, like so:
var outlineMaterial = new THREE.MeshBasicMaterial( { color: 0x00ffff, side: THREE.BackSide } );
outlineMesh = new THREE.Mesh( geometry, outlineMaterial );
outlineMesh.scale.multiplyScalar( 1.05 );
mesh.add( outlineMesh );
three.js r.67