Introducing ‘First Hand,’ Our Official Hand Tracking Demo Built With Presence Platform’s Interaction SDK

The Power of Direct Interactions

10 Tips to Get Started with Interaction SDK

1. In the past, we’ve manually authored hand poses for every item in a game—and it could even take a few iterations before the pose felt natural. With Interaction SDK’s Hand Pose Authoring Tool, we could launch the Editor, reach out and hold the item in a way that felt natural, and record the pose, and it would be usable straight away. Recording poses became so simple that within a minute we could have more poses recorded than we could ever need for an item, and we would then filter those down to a core set of hand poses.
2. Interaction SDK supports tracked hands and controller “Hands” out of the box with a structure that allows both input systems the flexibility to play to their strengths. “Hands” use a very modular system to extend the basic functionality with additional features like velocity tracking and pose recognition. If you’re planning to support tracked hands and controllers, make sure that, as you add more features to your tracked hand inputs, you add the features to the controller inputs too.
3. Predictably, a great chunk of Interaction SDK’s functionality is driven by “Hands,” and you can expect to find many areas in the SDK where you’ll have to link up “Hands” to your functionality. To make this easier to manage, Interaction SDK provides “HandRef,” a component that acts as a substitute/proxy for a real “Hand” object. This is especially useful in prefabs where swathes of functionality can be wired up to a HandRef within the prefab—then only the HandRef needs to be linked to the real “Hand.”
4. Many of Interaction SDK’s features like pose recognition, gesture recognition, and collision detection expose their functionality through the IActiveState interface, which is about as basic as it gets—either returning true or false based on the current state. Multiple ActiveStates can be combined together to trigger any number of gameplay events. The majority of gameplay in First Hand is driven in this way.
5. You can build touchable interfaces using Unity UI in exactly the same way you’re used to. Adding a PointableCanvas to the UI Canvas is all that’s needed—everything else just works.
6. “Snap Interactors” are great for drop zone interactions and fixing items in place. They’re used extensively in First Hand throughout the experience but especially during the Glove building sequence where “Snap Interactors” trigger its progression.
7. For small objects, particularly objects that don't have a natural orientation or grab point, it can feel restrictive to use pre-authored hand poses since the player could hold them however they like. Interaction SDK’s “Touch Grab” feature uses the physics shape of the object to create poses for the hand dynamically. Examples of this in First Hand are the glove parts, which the player can pick up in whatever way feels natural to them.
8. Interaction SDK’s “Distance Grab” is easy to configure—essentially a cone extending out from the hand that selects the best candidate item. When setting up an item for “Distance Grab,” it makes sense and saves time to reuse the same hand poses that were set up for regular grab.
9. Creating prompts to guide the player through First Hand worked especially well. Using Hands through Link, we were able to create animation clips directly within the Editor. They took very little time to create and were usable immediately.
10. There’s plenty going on in First Hand, including interactions, effects, audio, and unique gameplay elements. Managing how all these are triggered was improved by Interaction SDK’s extensive catalog of events—nearly every feature in Interaction SDK provides some way of hooking into its events, making it very easy to trigger custom behavior.