Mobile

Grab Interactions in Mobile

Horizon Creator Academy

Hands-On Challenge: Grab Interactions in Mobile

Create custom UI panels
Build an interactive custom UI
Player-specific custom UI
Video Presentation on how to build performant CUIs

Hands-On Challenge Overview

This challenge focuses on setting up and optimizing grab interactions for mobile users, ensuring objects feel natural and intuitive to hold.
You’ll learn how to:
  • Make an object grabbable.
  • Differentiate between physics and non-physics grabs.
  • Use Grab Anchors to define a custom holding position (grip pose).
  • Test and refine grab interactions for mobile.
Estimated Time: 1 hour

What You'll Need:

  • Windows PC
  • Access to the Worlds Desktop Editor

Challenge Steps:

1. Create a Grabbable Object
  • Create a simple object you want players to pick up. A coffee mug is a great example. You can search for one in the public assets.
  • In the object's Properties panel, you can set its physics behavior.
  • Non-physics grab: The object remains unaffected by gravity when released by the player. To set this, set the Motion to Interactive, the Interactivity to Grabbabe.
  • Physics-based grab: The object will react to gravity and collisions. This is great for throwable items like a ball. To set this, set the Motion to Interactive, the Interactivity to Both, and ensure the object has collision enabled.
2. Set the Grip Pose and Grab Anchor
  • With the object selected, go to its Properties panel and select one of the many Grip Poses. This determines the player’s animation when holding the object.
  • You can also enable Grab Anchor. This allows you to control exactly where the player's hand will attach.
  • By default, the hand will grab the object's center. Adjust the anchor position and rotation.
3. Test Your Grabbable Object
  • Enter Preview Mode to test the interaction.
  • Observe how your avatar's hand attaches to the object. Does it look natural? If not, exit preview mode and continue adjusting the grab anchor settings until it feels right.
  • Test our throwing the physics-enabled object.

Level Up:

  • Add sound effects that play when the object is grabbed and released to provide players with more feedback.
  • Use scripting to implement force hold and force release. For example, create a button that forces a player to grab an object and another that forces them to release it. This can be useful for creating guided experiences or tool management systems.

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