In this Tutorial we will illustrate the construction and configuration of three scripted doors: the Sliding Door, the Double Sliding Door and the Swinging Door.
Both doors are presently a bit simple. We'll be updating both the doors themselves and the wiki as needed.
Doors could be said to be complex game objects. They are structured collections of GameObjects and Components, and how they are assembled and "wired up" is essential to their operation. They will typically consist of some sort of framing in which the door proper and possibly a hinge sits, and the door, which may be a single mesh or in the case of the swinging door, an empty GameObject "hinge" to which the door mesh is a child.
Additionally, the various GameObjects will have certain components associated with them, typically to facilitate user interaction and to animate the GameObject.
Setting up doors can be a bit tricky, but creating content for unity is not for the faint of heart. Hopefully, with this tutorial we can make that workflow somewhat less painful for Space creators.
The Single Panel Sliding Door is perhaps the simplest possible articulated door. Before we get into a step-by-step walkthrough of it's construction, lets break it down conceptually from the top level.
Firstly, there are three requirements of any door:
Given these requirements, we could say that we will need a structure for the door frame, of arbitrary complexity, and a structure for the door proper, of equally arbitrary complexity.
For this door, our doorframe will be fairly complex, consisting of a transom piece, a threshold piece, and left and right door posts. The door will be a single cube mesh of appropriate size and proportions to fit suitably within the frame.
To get started, create a new project for space, or perhaps use one that you have available for experimentation and development. Use the Main Menu to create the first of the cubes we'll use (Main Menu: GameObject->3D Object->Cube). Just under the left side of the main menu, click the button to expose the scaling tools. Scale the cube a bit higher than the head of the avatar you would use to walk through the door, and then a little wider than that avatar; on the remaining axis, make it proportionately thick.
Next duplicate this cube. Be sure it is selected, as in the image above, then on the object in the hierarchy, right click->Duplicate. Now switch to the translation tool, and move the copy along the X axis until it is clear of the door. Switch back to the scaling tool, and edit the thickness in each horizontal direction to form the left door post. Duplicate this one just as you did the door previously, and using the translate tool, move it to the right of the door.
Perform similar operations for one each of a transom (above the door) and a threshold (below the door). It should look something similar to the image below:
Now, we can't very well just fling down a couple of cube meshes and expect it to behave as a door; and we really need to start organizing things as a unit. This will be important structurally. Note also that the door's 'frame' is not as simple as it could be; it really just needs to be any rigid body mesh. The one constraint is that animation of the door will occur relative to this piece; it can be as simple oras elaborate as you like. I'd perhaps stop short of making it the bulk of a building's construction.
So first, lets rename those cubes. Let's make sure to get the names right, recognizing them will be important a little later in the process. Additionally, some structure will be important. Within the hierarchy window, create an empty GameObject (RightClick Hierarchy Window->Create Empty). Drag all the door and door frame pieces and drop them on the empty GameObject; then (again, in the hierarchy window) rename the game object something like 'SinglePanelSliding Door'. It should resemble the following image; no changes should occur in the geometry of your construction; only the logical structure in the hierachy window.
Should your door objects be oddly nested, just drag them all out and nest them as showin in the image below.
This structure is actually very important, if not elaborate. We're working with the simplest possible door, so the structure is the simplest possible; but rest assured that it is crucial to the operation of the door.
The next step is to begin adding the components to the structure that facillitate it's operation.
First select the container GameObject created and renamed in the last step. Then click the large 'Add Component' button at the bottom of the inspector pane in the Unity interface. In the search field at the top of the window that appears, type 'Animator'. Click on the Animator component that appears as a search result, adding the component. Repeat once for each of 'Box Collider' and 'Proximity Activator'.
Lastly (for this step), resize the box colider as shown in the following image. Editing the box colodier is initiated by clicking the icon labelled 'Edit Collider' in the inspector pane. Editing the colliders uses a slightly different interface than other unity editing widgets. There are small dots in t he face center of each of the collider's faces; these are handles for translating the face along it's perpendicular axis. This is the only type of editing operation to which a box collider can be subjected.
Next, in the inspector tab for the box collider, click the box for 'Is Trigger'. This will turn off collisions in a physics simulation sense, and enable the collider to behave as a sensor that triggers it's associated Proximity Activator. The Proximity Activator script multiplexes various signals to the animations defined in the Animation Controller configured within the Animator component. In our construct, these signals take the form of strings that are sent up as a result of the occurance of the events 'Activate' and 'Deactivate'. Multiple reactions to each of these two events may be configured in the inspector using the '+' button. They can also be removed with the '-' button.
At this point, it would probably be a good idea to create a folder in your project to contain the various elements of the animation. But you already did that probably :) If not, do that now, and get into the folder. Right click the emptiness, and Create->Animation Controller. Double clicking the object in the folder (the Animation Controller) will allow you to begin editing the component. Before you do though, be aware we still don't have animation(s) created for the door, so what you see there will neccessarily reflect that degree of completion of the project.
The animation controller is what is referred to as a Finite State Machine or FSM. It is configured with an interface called a Node Editor. More on that in a few minutes.
When you've finished fiddling with the Animation Controller (hopefully you didn't change stuff substantially), make sure you have the top-level door game object selected, and press 'Ctrl 6' on your keyboard. This will open the animation editor. The animation editor is a scene graph editor. Almost anything can be animated in unity. If you can click on it in the hierarchy and see modifiable properties in the inspector pane, chances are it is possible to use a scene graph to generate values for that property over the course of time.
We will be using the scene graph editor to create three scene graphs: 1. the door in it's inactive state. This is essentially empty from an animation perspective. 2. The door transitioning from it's idle, closed state to an open state. and finally 3. The door transitioning from it's open state to it's closed state. These animations will form the basis for what happens once the collider triggers the proximity activator, once it sends up the appropriate signals to the animation controller via the animator component. Starting to get the picture here? don't worry, if it hasn't already, it will start to come together soon.
Following is a screenshot of the unity editor with the animation controller exposed in the node editor interface, as it looks without our animations in the object's context:
| |||||
| |||||||||||||||||
| ||||||||||||||||||||||||||||||||||||||
| |||||||||||