I’ve been waiting patiently for Apple to reveal their headset for at least 5 years now, and as of WWDC 2023, that wait is finally over. A couple of weeks later (last Tuesday), the developer tools dropped, and I finally got a chance to start working with the frameworks and applications that Apple has created for making content on their new headset.

I’ll be eagerly exploring these frameworks and playing with this tech at least until the headset is covering my eyeballs, and (hopefully) for years after. There’s literally so much here that they devoted over 40 (admittedly short) WWDC talks to the topics, (with some overlap, sure, but not as much as you’d think). I have done a fair bit of VR development in the past, and while it’s been a few years, (and I’m sure there’s been some improvement in that time), to me, Apple’s APIs seem like the most flushed-out and easy-to-use way to develop 3D applications that I have ever seen. The only downside I can imagine is the vast amount of new frameworks to learn. There are seemingly a lot of ways to approach the same problem, or similar problems anyway, and I could imagine that being daunting for a lot of people. Fortunately, the documentation is quite good.

I imagine I’ll be writing about this topic a bunch in the next few months, and for my first post on the topic I’m going to just document some of my findings about the coordinate system in visionOS. I’ll jump right in.

position coordinates in immersive space

So I’ve been doing some programmatic drawing experiments on visionOS, and as anyone who has ever drawn things on a screen knows, one of the first things you need to know is:

Where is the center of your drawing area, or x: 0, y: 0, z: 0?

In short, when you open an Immersive Space in visionOS, 0,0,0 is positioned directly beneath you.

While the immersive space remains open – even while you move around within the space – 0,0,0 doesn’t move. But if you close the immersive space, and re-open it, 0,0,0 will have moved to a new location and rotation, again directly beneath your feet, and rotated to face the same way you are facing.

So, because the coordinate space will always appear in the same orientation as you, the following are always true (when you first open the space):

• -x is to your left, and +x is to your right
• -y is down, while +y is up
• -z is forward, and +z is backward (behind you)
  I’m not sure I love that last z-direction decision, but it’s how it works.

Note that animating a transform is as easy as this code snippet:

.gesture(TapGesture().targetedToAnyEntity().onEnded { value in
    var transform = value.entity.transform
    transform.translation += SIMD3(0.1, 0, -0.1)
    value.entity.move(
        to: transform,
        relativeTo: nil,
        duration: 3,
        timingFunction: .easeInOut
    )
})

That example is from the WWDC video Develop your first immersive app.

I have a long list of things to explore next, but at some point in the near future I’ll be exploring drawing and transforms and coordinate spaces in what apple is calling “volumes”. (Volumes are 3D windows, or bounded boxes, essentially.)