HYTOPIA Entities

This skill helps you create and manage entities in HYTOPIA SDK games.

Documentation: https://dev.hytopia.com/sdk-guides/entities

When to Use This Skill

Use this skill when the user:

• Wants to create game objects, NPCs, items, or interactive objects
• Needs to spawn or despawn entities
• Asks about entity components or behaviors
• Wants to animate entities or handle entity lifecycle
• Needs collision detection between entities
• Asks about player entities vs non-player entities

Core Entity Concepts

Creating an Entity

import { Entity } from 'hytopia';

class MyEntity extends Entity {
  constructor() {
    super();
    // Initialize entity properties
  }
  
  onSpawn() {
    // Called when entity is spawned into the world
  }
  
  onDespawn() {
    // Called when entity is removed from the world
  }
  
  tick(deltaTime: number) {
    // Called every frame - use for continuous updates
  }
}

Spawning Entities

// Spawn an entity in the world
const entity = new MyEntity();
world.spawnEntity(entity, {
  position: { x: 0, y: 10, z: 0 },
  rotation: { x: 0, y: 0, z: 0 }
});

// Despawn when done
world.despawnEntity(entity);

Entity with Model

import { Entity, Model } from 'hytopia';

class ItemEntity extends Entity {
  constructor() {
    super();
    this.model = new Model({
      modelUri: 'models/sword.gltf',
      scale: 0.5
    });
  }
}

Entity Components

import { Entity, PhysicsComponent, HealthComponent } from 'hytopia';

class EnemyEntity extends Entity {
  constructor() {
    super();
    
    // Add physics
    this.addComponent(new PhysicsComponent({
      mass: 10,
      colliders: [/* collision shapes */]
    }));
    
    // Add health
    this.addComponent(new HealthComponent({
      maxHealth: 100,
      currentHealth: 100
    }));
  }
}

Common Patterns

Following Player

tick(deltaTime: number) {
  const player = world.getClosestPlayer(this.position);
  if (player) {
    const direction = player.position.subtract(this.position).normalize();
    this.position.add(direction.multiply(5 * deltaTime));
  }
}

Projectile Entity

class Projectile extends Entity {
  velocity: Vector3;
  lifetime: number = 5;
  
  tick(deltaTime: number) {
    this.position.add(this.velocity.multiply(deltaTime));
    this.lifetime -= deltaTime;
    
    if (this.lifetime <= 0) {
      world.despawnEntity(this);
    }
  }
}

Best Practices

1. Always clean up in onDespawn() - remove event listeners, stop sounds
2. Use tick() sparingly - expensive operations every frame hurt performance
3. Pool reusable entities - don't constantly spawn/despawn the same type
4. Set proper collision layers - use layers to filter what collides with what
5. Network efficiently - only sync properties that change and need to be visible to clients

Common Mistakes to Avoid

• Don't forget to call super() in constructor
• Don't modify entity properties directly on the client - server is authoritative
• Don't spawn entities before world is initialized
• Don't forget to handle entity cleanup on game end