The amount of child elements in Three.js

Question

The amount of child elements in Three.js

After creating a three js object and adding some children to it, I changed the length of children to 0. As a result, the objects went out of screen. But will this action completely remove the objects from both the screen and memory?

var balls = new THREE.Object3D();  // parent

To create children:

var geometry = new THREE.SphereGeometry(5, 32, 32);
var material = new THREE.MeshPhongMaterial({color: 0x0f0ff0, shininess: 50, transparent: true, opacity: 1});
var sphere = new THREE.Mesh(geometry, material);
sphere.position.x = scale('some random value');
sphere.position.y = scale('some random value');
balls.add(sphere);

The above steps were repeated for more spheres.

Then in the console, I entered:

balls.children = [];

This action removed all the spheres from the scene. But does this also erase all the sphere objects from the memory?

javascript three.js

Answer 1

Answer №1

A common way to clear all elements in an array is by setting array.length = 0;. This action effectively deletes all elements within the array. Alternatively, if you set array.length = 2, only the first two elements will remain in the array while the rest are deleted. In Javascript, there is a built-in function known as slice() that also performs a similar operation.

Answer 2

A common way to clear all elements in an array is by setting array.length = 0;. This action effectively deletes all elements within the array. Alternatively, if you set array.length = 2, only the first two elements will remain in the array while the rest are deleted. In Javascript, there is a built-in function known as slice() that also performs a similar operation.

Answer 3

Answer №2

To properly delete a child, it is recommended to first call remove(child) on the parent object, and then utilize dispose() for the child's material and geometry.

Here is an example in your code:

var balls = new THREE.Object3D(); // parent

var geometry = new THREE.SphereGeometry(5, 32, 32);
var material = new THREE.MeshPhongMaterial({color: 0x0f0ff0, shininess: 50, transparent: true, opacity: 1});
var sphere = new THREE.Mesh(geometry, material);
sphere.position.x = scale('some random value');
sphere.position.y = scale('some random value');
balls.add(sphere);

// Perform certain actions

balls.remove(sphere);
geometry.dispose();
material.dispose();

Remember to only dispose of the material/geometry if they are no longer being used by any other Mesh instances.

According to THREE.Object3D, in the method remove(object, ...):

"Removes the specified object as a child of this object. Multiple objects can be removed at once."

As per THREE.Geometry, in the function dispose():

"Ensure you call this method when disposing of a geometry to prevent memory leaks."

Similarly, from THREE.Material, in the method dispose():

"Use this to dispose of the material. Note that textures belonging to the material should be disposed separately using Texture."

If textures from textures are employed, make sure to dispose of them as well.

(Version: THREE.js r85).

Answer 4

To properly delete a child, it is recommended to first call remove(child) on the parent object, and then utilize dispose() for the child's material and geometry.

Here is an example in your code:

var balls = new THREE.Object3D(); // parent

var geometry = new THREE.SphereGeometry(5, 32, 32);
var material = new THREE.MeshPhongMaterial({color: 0x0f0ff0, shininess: 50, transparent: true, opacity: 1});
var sphere = new THREE.Mesh(geometry, material);
sphere.position.x = scale('some random value');
sphere.position.y = scale('some random value');
balls.add(sphere);

// Perform certain actions

balls.remove(sphere);
geometry.dispose();
material.dispose();

Remember to only dispose of the material/geometry if they are no longer being used by any other Mesh instances.

According to THREE.Object3D, in the method remove(object, ...):

"Removes the specified object as a child of this object. Multiple objects can be removed at once."

As per THREE.Geometry, in the function dispose():

"Ensure you call this method when disposing of a geometry to prevent memory leaks."

Similarly, from THREE.Material, in the method dispose():

"Use this to dispose of the material. Note that textures belonging to the material should be disposed separately using Texture."

If textures from textures are employed, make sure to dispose of them as well.

(Version: THREE.js r85).

The amount of child elements in Three.js

Answer №1

Answer №2

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