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ECS stands for Entity Component System. It's a design pattern often used in game development that promotes flexibility and performance. In ECS:

  • Entities are identifiers for game objects.
  • Components are raw data for different aspects of the game object, such as position or health.
  • Systems are logic that transforms components from one state to another.

Defining Components

Components can be defined in the glTF file using the MX_components extension.

This can be accomplished using Unity3D with the accompanying ThirdRoom plugin, and creating a class that inherits from ThirdroomComponent, like so:

using UnityEngine;

public class TestComponent : ThirdroomComponent {
  public float value = 1.25;

Once a component has been defined in the glTF, it can be accessed in the script via world.findComponentStoreByName.

const TestComponent = world.findComponentStoreByName("TestComponent");

Components can be added, removed, retrieved, and existence checked on any node.

const node = world.createNode();


console.log(node.hasComponent(TestComponent)); // true

const testComponent = node.getComponent(TestComponent);

console.log(testComponent.value); // 1.25


console.log(node.hasComponent(TestComponent)); // false


Queries can be used to obtain lists of nodes with certain components.

const testQuery = world.createQuery([TestComponent]);

function TestComponentSystem(time) {
  for (const node of testQuery) {
    const test = node.getComponent(TestComponent);
    test.value += 1;
    console.log(test.value); // 2.25