Walking (and jumping) on your hands in VR

Last December, I decided to get myself an early Christmas present in the form of an HTC Vive VR headset. After a while, I started getting all kinds of ideas for things that might be fun to try to implement in VR (mostly games), so I thought I'd see if I could actually code something for it.

I downloaded OpenVR and got the samples to compile. On New Year's Eve, I did my first hand-walking test (by changing not so many lines in OpenVR's hellovr_opengl sample). The experiment eventually lead to a lot of other exciting things that I also want to write about. But I want to start start from the beginning, so today I'll talk about the original hand-walking test.

So, why did I want to experiment with ways to get around in VR?

Getting around in VR

The Vive is built for room scale VR, which means that it can track the position of your headset as you walk around in your room. Pretty much all Vive applications that I've tried let you walk to cover short distances. When you get close to the boundaries of the play area, the Vive draws the boundaries in VR so that you can avoid bumping into something. As long as the virtual space that you want to move around in is the size of your play area, I think it's a solid VR experience.

In most VR applications that I've got my hands on, you cover longer distances by teleporting. I think that it works ok, but it still feels a bit unnatural. Especially when you try to walk somewhere, realize that your room is too small, so you have to walk back to where you started and then teleport forward.

The setup where walking around in physical space is directly tied to moving in VR space also brings some limitations. You're pretty much limited to flat floors. And you can usually walk through obstacles as if you were a ghost, or at least put your hands through them. If only there was a better way!

The Biped Box

Since I wanted an experience that felt less like being like a ghost, I decided to focus on the hands and head, which are the only things that the Vive tracks. They, at least, could be physical. Basically, you'd play as a biped with a head and feet, with the feet controlled by your hands.

The idea of the test was simple:

• I would place the player inside a big box.
• The box would fall upward.
• I put spheres on the hands and head (that is, on the controllers and the headset).
• When one of the box's sides collided with a sphere, there would be an inelastic collision (which would set the box's velocity to match the sphere's).

The result is that

• You can walk around by using your hands as feet.
• When standing still, the floor usually goes up to your waist or so (up to your neck if you raise both arms).
• You can jump (several meters high) by flicking one of your hands down through the virtual floor.

I also added a way to climb in the air by letting you grip anywhere in the air by holding down a controller button.

Even though I originally modelled it as the box moving and falling upward, with no other visual frame of reference, of course you perceive it as yourself moving and falling downward.

But how does it feel?

My kids (then aged 7 and 8) came in and wanted to try it. First response: "Dad, this is creepy." Then, as the other one was trying it: "Can I go again?"

So, it does take a little time getting used to. It's probably best if you get a bit of regular VR experience under your belt first, including getting over the worst of your fear of virtual heights. It's a lot easier to keep your balance if you keep your feet still while you are flying through the air.

According to my own experiences:

• You get used to only your head and hands being physical pretty quickly.
• Jumping is fun!
• You can even make some wall jumps (jump toward a wall, then jump off it) if you time it right.
• Climbing in the air, or pretending to climb on walls and the ceiling is also fun. (A number of people seem to find it more fun than jumping.)
• There's a bit of a thrill to falling and landing, but it works fine.
• Walking with your hands works, but feels a bit clunky.

Now, I've tried this on a few people, and the way you respond to the experience seems to vary quite a bit from person to person. Me and the kids think it works great. My wife is a bit uneasy with it. My brother, who doesn't have a lot of VR experience, didn't have any problems. One friend did, another didn't. I don't have nearly a large enough sample do draw much conclusions about how common it is that people enjoy this kind of experience.

There are worse ways to get around

On the other hand, if I compare to moving through VR using a gamepad in classic FPS (First Person Shooter) like fashion, there is no question about what feels more comfortable to me. When trying VR games, I bought one, which I quickly realized, was not a really a VR game. It was a plain first person PC game with a VR mode added on afterward.

Now, that was an uncomfortable experience to me! When I would move the analog stick on the gamepad, my speed would instantly jump from standstill. If I wasn't holding the gameped exactly facing forward, my movement direction would feel off. When I was traversing uneven terrain, I would be haplessly weaving up and down to follow the surface of the ground. To avoid feeling really sick, I had to consciously focus on looking in the direction I was moving the whole time.

Myself, I haven't had any similar issues with my hand-walking experiments. I believe that the reason that it works as well as it does is that what happens follows pretty directly from your experience with the physical world and your intentions.

Is this a better way?

So, is there a better way to move about in VR space in first person than walking short distances and teleporting? I still don't know, but hand walking as a biped is definitely different. It has some clear advantages, but also some disadvantages. I see a lot of potential for it:

• You can seamlessly move around in a big world and really feel like you're physically interacting with it at every step.
• It's not restricted to moving around on flat surfaces.
• Instead of walking through obstacles, they will actually push you back.

I'm really sold on it! As soon as I did the experiment, I thought that it would be interesting to try to make a game based on hand walking mechanics. (I'm still looking into that.)

On the other hand, it's not for all VR experiences, and, it seems, not for all people. I don't know what kind of percentage of people that enjoy this kind of thing, but I'd really like to find out! Do you have a Vive/Rift/similar headset and want to try it out? Then please find Biped Box in the downloads section (or try one of the other demos) and write me a line about your experience!