Check if a cube is added to the scene

Questions
1

I can add a cube to the scene with this code:

scene.add(cube1)

and remove it:

scene.remove(cube1)

But the doubt is… there is any property of scene object which checks if cube1 is into the scene or not?

2

There are three ways to achieve this :

Option 1: Check using scene.children

const isInScene = scene.children.includes(cube1);
console.log(isInScene); // true if cube1 is in the scene

Option 2: Use scene.getObjectById()

Every object in Three.js has a unique id. You can use this to check:

const isInScene = scene.getObjectById(cube1.id) !== undefined;
console.log(isInScene); // true if cube1 is in the scene

Option 3: Use scene.getObjectByName()

If you have given your object a name, you can check for it:

cube1.name = "MyCube";
const isInScene = scene.getObjectByName("MyCube") !== undefined;
console.log(isInScene); // true if cube1 is in the scene

If you’re working with many objects, it might be useful to use unique names or keep a separate record of objects you’ve added to the scene for easier management. However, the scene.children.includes() method is generally sufficient for simple use cases.

3

I tried to add with this only when them load:

	for(i1 in players){
		if(!players[i1].cube){
			players[i1].cube=new THREE.Mesh(box2,green_material)
		}
		if(!scene.children.includes(players[i1].cube)){
			scene.add(players[i1].cube)
		}
		console.log(scene.children.includes(players[i1].cube))
		players[i1].cube.position.set(players[i1].x,calcSurface(players[i1].x,players[i1].z)+3,players[i1].z)
	}

But the scene show at this form:

image
image1919×775 157 KB

image
image1919×867 187 KB

EDIT:
Another times its appears as this:

image
image369×313 61.3 KB

EDIT 2:
I suspect that this bug is the supression of this fragment of code:

	for(i1 in players){
		try{
			scene.remove(players[i1].cube)
		}catch(e){
			console.warn(e.message)
		}
	}

EDIT3:
Now it shows this weird bug:

image
image1682×815 174 KB

EDIT4:The result:

image
image321×386 87 KB

The code:

box2=new THREE.BoxGeometry(1,2,1)
green_material=new THREE.MeshLambertMaterial({color: "rgb(0,255,0)" })

update=()=>{
	requestAnimationFrame(update)
	for(i1 in players){
		if(!players[i1].cube){
			players[i1].cube=new THREE.Mesh(box2,green_material)
		}
		if(scene.children.includes(players[i1].cube)){
			players[i1].cube.position.set(players[i1].x,calcSurface(players[i1].x,players[i1].z)+3,players[i1].z)			
		}else{
			scene.add(players[i1].cube)
		}
	}