Hands-On Challenge: Sending, Receiving and Ownership in Scripting

Hands-On Challenge Overview

• Transfer ownership of entities
• Send and receive events
• Use event listeners for built-in interactions (Code Block Events)
• Coordinate behaviors between entities (e.g., button and door)
• Understand server vs. local ownership and why it matters for responsiveness

What You’ll Need:

• Access to the Worlds Desktop Editor
• An existing world project or a new one to work in.
• Basic familiarity with Worlds TypeScript and scripting APIs

Challenge Steps:

• Add two empty objects to your world and name them "ServerDoor" and "LocalDoor". Add a mesh (e.g., a cube or panel) as a child of each to visually represent the doors.
• Add a Trigger Gizmos to your scene and place it near the doors.

• Position the Trigger Gizmo where you want players to activate the doors.
• In the properties panel of the Trigger Gizmo, press the Attach Script button. Then, click New Trigger Script at the bottom of the list.
• Click the 3 dots on the right side of the script that you created, and click edit script.
• This should open your code editor with a default UI template. Click the 3 dots on the right side of the script that you created, and click edit script.
• This should open your code editor with a default trigger template.

• Define a property for your local door using PropTypes.Entity so you can assign it in the editor.
• Example:

static propsDefinition = {
  localDoor: { type: PropTypes.Entity },
};

• Add an onPlayerEnterWorld event and create a new method for it. In the new method, assign the localDoor owner to the player.
• Example:

start(){
  //…other trigger events
  this.connectCodeBlockEvent(this.entity, CodeBlockEvents.OnPlayerEnterWorld, this.onPlayerEnterWorld);
}
onPlayerEnterWorld = (player:Player) => {
  this.props.localDoor?.owner.set(player)
}

• Create a new script in the code editor called Events.ts.
• In this new file, add a network event.
• Example:

import { NetworkEvent } from "horizon/core";export const OpenDoorEvent = new NetworkEvent("openDoor")

• On the Trigger script, add a send network broadcast event in onPLayerEnterTrigger.
• Example:

OnPlayerEnterTrigger(player: Player) {
  this.sendNetworkBroadcastEvent(OpenDoorEvent, {})
}

• To script the doors, create a new script file for each door (e.g., LocalDoor.ts and ServerDoor.ts).
• Below is an example of how to implement the logic for a door that opens in response to a network event:

import { OpenDoorEvent } from 'Event';
import * as hz from 'horizon/core';

class LocalDoor extends hz.Component<typeof LocalDoor> {
  static propsDefinition = {};

  shouldOpen = false;
  startPosition = hz.Vec3.zero;
  endPosition = hz.Vec3.zero;
  timeElapsed = 0;
  maxTime = 3;

  start() {
    this.startPosition = this.entity.position.get();
    this.endPosition = this.startPosition.add(new hz.Vec3(0, -1, 0)); // Move down 1 unit
    this.connectNetworkBroadcastEvent(OpenDoorEvent, this.onOpenDoor.bind(this));
    this.connectLocalBroadcastEvent(hz.World.onUpdate, this.onWorldUpdate.bind(this));
  }

  onOpenDoor() {
    this.shouldOpen = true;
  }

  onWorldUpdate(data: { deltaTime: number }) {
    if (!this.shouldOpen) return;
    this.timeElapsed = Math.min(this.maxTime, this.timeElapsed + data.deltaTime);
    const t = this.timeElapsed / this.maxTime;
    const newPosition = hz.Vec3.lerp(this.startPosition, this.endPosition, t);
    this.entity.position.set(newPosition);
    if (this.timeElapsed === this.maxTime) {
      this.timeElapsed = 0;
      this.shouldOpen = false;
    }
  }
}
hz.Component.register(LocalDoor);

• To create a server door, copy this code and rename the class and script file to "ServerDoor".
• Assign the LocalDoor script to the LocalDoor entity and the ServerDoor script to the ServerDoor entity in your world.
• Important: For the LocalDoor script, set its execution mode to Local in the Script Panel.

• Enter play mode and walk into the Trigger Gizmo.
• Observe the difference: the server-owned door may have more latency, while the locally owned door should open more responsively.

Level Up:

• Test out how ownership transfer affects gizmos, like particles gizmo and projectile gizmo. See how they become more responsive when playing them in local scripts.
• Try broadcasting an event, local or network, that multiple entities respond to at once.

Need Help?

• Forum Support: Reach out to the MHCP community in the creators forums in the Questions & Discussions ⁠category.