One of the best ways of learning to make things in something like Unity is to look at examples which show you how the professionals have done it. And there are lots of great Unity examples out there and I'm going to look at the VR samples project which is available for free on the Asset Store, and it's designed exactly for that. It's created by the makers of Unity to help you get started. And it's got a lot of games. For example, this is a shooting game. If you can see, there's little red dots and that's where I'm looking. So I'm moving my headset around. If I hover over that sign and click a button, it selects it. So this is all gaze-based interaction. And similarly, gaze-based interaction for the game itself, I look at targets, and I press a button to shoot them. This is just one example. Another example is the Flyer. Again, I've got that little button. And here, I'm controlling the spaceship and I'm controlling this spaceship with my gaze as I move my head mounted display around. So, I'm just moving my HMD around and that's controlling the direction of the space ship, and I'm supposed to fly through these circles. So, it's nice to have those examples but the value of them isn't just by looking at things and playing them, but it's actually, you can see how it was made. So if I open the shooter example up again, we can see that there are a whole bunch. It's a full project, so I can see all of the objects in here. So, I've got, for example, my weapon here. If I switch to zoom mode, I can zoom in on that. But obviously, the more interesting things are in the camera and, for example, the camera now has its own user interface and there is here a GUI system which contains all of the introductory stuff, the title of body where it says, "Press FIRE to shoot," targets within the time limits, the instructions, and there's also the selection slider which is the button that you can see it here. The button that you hover over with your gaze and you click on to make it happen, and it's a slider because you'll gradually, as you're looking at it, gradually fills up and when it's full, it means you've selected it. Now, these are all examples of interactivity. And in a system like Unity, the interactivity comes from scripts. Now, scripts are made of code so they are little programs that sit within Unity to control how you interact with objects. And you can add scripts to objects. So, going over to the inspector over here on the right-hand side, you can see that there's a VR Raycaster script here. And that's an example of a thing that you can add to an object to do something. And this is a really important one because it's added to the main camera, and what VR Raycaster does here is it controls how you interact with things with your gaze. So, when you look at something, it's like it shoots out away. You don't see it. It's not a real ray, but it's a sort of mathematical ray. And that ray sees, if that ray collides with anything, you know that you're looking at it. So, for example, if I'm looking at the bottom, it will shoot out away from the camera and if that ray hits the button, it knows I'm looking at the bottom. And then, this is the trigger for most of the interaction that happens in these examples. The other important script is VR Input, and that's just going to take in input from the HMD and from any controllers. In this example, it's just used for the button presses. So, to get this functionality, all you need to do is to import, to add all these scripts to your object, and I'll show that in a minute. But the other thing I want to show is that objects need to be able to respond to your Raycasting. So, how do we do that? Well, let's look at the example, the slider that has a script on it called VR Interactive Item in the middle here, and that VR Interactive Item is a script that recognizes when something's been selected by the VR Eye Raycaster script. And when that happens, it responds in some way. And you need some other script that actually do the response. So here, the Selection Slider script is actually creating that response. And over the next few weeks, we'll look at a bunch of those scripts that do that kind of response.
