Instantiate meshes for each child object using traverse

Questions
,
1

hi everyone,

please take a look on this model in blender,
it has three objects

what i want is to load and position another 3d object on each lightpos object

here what i have tried :

1 - export to obj
2 - traverse the loaded 3d model and store the child objects in an array
3 - load the second object and make a clone as a child for each sub object

here the code :
var scene, mainobj;
var lightpos = [];
var loader = new THREE.OBJLoader();
loader.load(

            "mainobject.obj",
         
            function (obj) {
            
   `mainobj = obj;`
                scene.add(mainobj );
            
               lightpos.splice(0,lightpos.length);
               mainobj .traverse( function ( child ) {
                if ( child instanceof THREE.Object3D  ) {
                 
                
                    if ((child.name).startsWith("lightpos"))
                    {
                        lightpos.push(child);
                    }
                    }});
            });     
		
		......

then with some button click
var loader = new THREE.OBJLoader();
loader.load(

            "childobject.obj",
         
            function (obj) {
 
                  var mesh = new THREE.Mesh(obj.geometry);
                lightpos.forEach(function(element) {
                
                   var instance = mesh.clone();
        
                    element.add(instance);
                 });

but no child object is rendered ,
and if i console log the mainobj variable , i can see that the child objects have been added

any idea on how to achieve this please ?

1 Like
2

Just an idea: Have you ensured “childobject.obj” is loaded properly?
If so; you can log the child positions to make sure they are where you want.

3

the child objects are loaded according to the console
and theirs positions are (0,0,0)

also their respective parents are the childs objects referenced during the first mainobject travese .

4

I would check that the second object is loaded as a normal object to be sure, if you have not done it yet.

5

yes the second object is loaded and the instance are created on the success callback …

then with some button click
var loader = new THREE.OBJLoader();
loader.load(

    "childobject.obj",
 
    function (obj) {

          var mesh = new THREE.Mesh(obj.geometry);
        lightpos.forEach(function(element) {
        
           var instance = mesh.clone();

            element.add(instance);
         });

the console.log show all the objects created in the tree …

6

Then I can only suggest to debug objects positions.

7

all the objects positions are 0,0,0 :confused:

8

And the lightpos ones?

9

all of them

10

Perhaps…

lightpos.forEach( function( element ) {
    var instance = mesh.clone();
    element.computeBoundingBox();
    element.getCenter( instance.position );
} );
11

after many tries it seem to work with collada files …