THREE.Object3D.add: object not an instance of THREE.Object3D

Question

so i'm getting this error and I cant find the source of it. I believe it has to do with me importing and creating my 3d objects in my scene but i'm not sure what i'm doing wrong.

here is the code: I call this function before I call init

function loadObjects()
{
loader = new THREE.JSONLoader();

var floorDiskmaterial = new THREE.MeshPhongMaterial({
    map: THREE.ImageUtils.loadTexture('img/floor_test.jpg'),
    transparent: true,
    color: 0xeaeaea,
    ambient: 0xeaeaea,
    overdraw: 0.5,
    //specular: 0x6a3e6d,
    shading: THREE.FlatShading,
    fog: false,
    //shininess: 50,
});

loader.load( "models/floorScene.js", function( geometry ) {
    FloorDiskFire = new THREE.Mesh( geometry, floorDiskmaterial);
    FloorDiskFire.position.set(0,0.2,0);
    FloorDiskFire.castShadow = true;
    FloorDiskFire.receiveShadow = true;
    FloorDiskFire.scale.set(1.5,1.5,1.5);
    //FloorDiskFire.rotation.y = -0.78;
} );

//-----Pillar Loader------//

var pillarMaterial = new THREE.MeshPhongMaterial({
    //map: THREE.ImageUtils.loadTexture('img/pillarMap.png'),
    //transparent: true,
    color: 0xeaeaea,
    ambient: 0xeaeaea,
    overdraw: 0.5,
    //specular: 0x6a3e6d,
    shading: THREE.FlatShading,
    fog: false,
    //shininess: 50,
});

loader.load( "models/pillar.js", function( pillar ) {
    firePillar = new THREE.Mesh(pillar, pillarMaterial);
    firePillar.position.set(135,0,135);
    firePillar.castShadow = true;
    firePillar.receiveShadow = true;
    firePillar.scale.set(1.7,1.7,1.7);
} );

loader.load( "models/pillar.js", function( pillar ) {
    earthPillar = new THREE.Mesh(pillar, pillarMaterial);
    earthPillar.position.set(135,0,-135);
    earthPillar.castShadow = true;
    earthPillar.receiveShadow = true;
    earthPillar.scale.set(1.7,1.7,1.7);
} );

loader.load( "models/pillar.js", function( pillar ) {
    airPillar = new THREE.Mesh(pillar, pillarMaterial);
    airPillar.position.set(-135,0,135);
    airPillar.castShadow = true;
    airPillar.receiveShadow = true;
    airPillar.scale.set(1.7,1.7,1.7);
} );

loader.load( "models/pillar.js", function( pillar ) {
    waterPillar = new THREE.Mesh(pillar, pillarMaterial);
    waterPillar.position.set(-135,0,-135);
    waterPillar.castShadow = true;
    waterPillar.receiveShadow = true;
    waterPillar.scale.set(1.7,1.7,1.7);
} );
}

Then in init I add the objects to the scene

loader.onLoadComplete=function(){
    scene.add(FloorDiskFire);

    scene.add(firePillar);
    scene.add(earthPillar);
    scene.add(waterPillar);
    scene.add(airPillar);
};

Answer 1

Ok here is the issue , the add call is invoked in wrong time , because i havent written this code from scratch and dont have time for very deep debugging , but i will give you a hint of what is wrong , and im sure you will find it easy to find the bug later , cause i think some of your objects are still loading while you are trying to add them to scene.

Procedure :

i changed

loader.onLoadComplete=function(){
        scene.add(FloorDiskFire);
        //scene.add(FloorDiskEarth);
        //scene.add(FloorDiskWater);
        //scene.add(FloorDiskAir);

        scene.add(firePillar);
        scene.add(earthPillar);
        scene.add(waterPillar);
        scene.add(airPillar);
    }

grouped the action in one new function called addObjects(); :

function addObjects(){
        scene.add(FloorDiskFire);
        //scene.add(FloorDiskEarth);
        //scene.add(FloorDiskWater);
        //scene.add(FloorDiskAir);

        scene.add(firePillar);
        scene.add(earthPillar);
        scene.add(waterPillar);
        scene.add(airPillar);
    };

then in your init() function i invoked the addObjects(); , but it still give the same error !! so i tried invoking it after sometime - in line 309 > index.html :

setTimeout(function(){addObjects();},1000);

please note that i have tried 100ms , and it didnt work , then 1 second works well , this is not a solution , it is just and indication that if you delay the function call everything will work fine , it is your job now to determine when to call it (i.e find the proper event to invoke the function ) as it appears that loader.onLoadComplete is not doing the job.

you can find the modified file here.

Answer 2

For those arriving here and looking for an alternate reason for getting this error, I got it because I loaded a GLTF object, but did not add it to the scene as a THREE.Object3D object.

A pared-down example of what I did wrong:

let example = new THREE.Object3D();
loader.load(objects.exampleGLTF, function (object){
    example = object;
    scene.add(example);
});

I was puzzled for a while, as I did various debugging to see that, indeed, it was loading, and waiting 5 seconds didn't make the problem go away.

The key was to add ".scene", as seen below.

let example = new THREE.Object3D();
loader.load(objects.exampleGLTF, function (object){
    example = object.scene;
    scene.add(example);
});