Our game environment should be dark, creepy, and suspenseful. But, every new Unity scene is created with a default, procedural skybox representing a cheery daytime, exterior. This needs to be changed. A skybox is ultimately a cube with flipped normals that surround and encompass the environment. Its faces contain an environment texture which, when mapped correctly, appears seamlessly across the model, creating the look of a vast skyline surrounding the scene. The primary purpose of our skybox should be to set a base and ambient lighting. The most appropriate skybox for our usage, then, is a night skybox or, at least, a dark, stormy (and perhaps slightly alien) skybox. There are many ways in Unity to create a skybox. One method is to create a cube-map texture (six separate textures) inside the image-editing software that maps to the faces of a cube. Another method, available in Unity 5, is a procedural skybox. Using this, Unity generates a skybox from some...

Now the fun begins, though logistically challenging, the process of level building. Our aim is to build a fun and interesting level. But this must be balanced against many factors, including level size, ease of navigation, variety, and more. Creating a level is challenging because misplaced or poorly designed elements stand out for their failings. They break the player's experience. Decisions about architecture and where to include straight sections, turns, jumps, ledges, props, and doors collectively influence the atmosphere and mood of a level. Here, we'll focus on the modular building method, piecing together an expansive level from reusable pieces, exploring reasons, and justifications for our choices along the way. However, let's first see the modular set in its entirety, that is, the complete collection of architectural meshes from which the level must be constructed.

Modular set for level construction

Each mesh is a modular piece (or module...

Let's start the level construction process. There are many ways to begin here, but it's a good idea from the outset to develop with a clean workflow in mind. By clean I mean an organized, structured, and easy-to-maintain workflow; one that remains maintainable for projects of many scales. First, delete any and all objects in the new scene, and then create a single empty GameObject named root by navigating to GameObject | Create Empty from the application menu. This object will be the top-most object in the hierarchy, from which everything else will be a child directly or indirectly.

Creating a root object for the scene

Next, create a new child object named env, which will contain all environment pieces. Make sure that both the root and env objects are positioned at the world origin at (0,0,0). I typically position the world floor at 0 on the y axis, making this the lowest point in the world. It is, of course, possible for objects to fall below...

Don't underestimate the design challenges faced when building a level. Arranging mesh modules meaningfully and constructing a layout that encourages exploration and invites interest is challenging. Is a corridor too long or too bendy? Is a walkway too narrow or too wide? Should there be a prop (such as a chair or a desk) in the corner of a room? These types of questions, and others, matter! They're not the kinds of things that should be settled just by flipping a coin. Consider the following design tips and tricks; that is, some guiding principles intended to help you build more interesting levels faster and easier.

Reaching this far you've now made a complete scene in terms of meshes representing the first level, composed from modular environment pieces (corridor sections). Presently, the level features no lighting, navigation meshes, music or audio, and Occlusion Data; but, we'll add these soon. Let's start with lighting. In Unity, there are three main lighting types or systems, which exist on a spectrum:

These are discussed in detail further here.

To start Baking Scene lighting, we'll first need to activate Lightmap UVs for the environment meshes and then position some lights in the scene where appropriate. To activate Lightmap UVs, select all environment meshes in the Project panel and enable Generate Lightmap UV from the object Inspector. Then click on Apply. This method is useful for generating a second UV channel when one doesn't already exist. This defines how lighting is baked to the lightmap texture. Unity applies an auto-unwrap projection using settings from the Advanced roll out. If, by contrast, your own meshes already have a custom, second channel, then you can use this channel instead for Lightmap UVs simply by disabling Generate Lightmap UVs.

Configuring Lightmap UVs

Our scene now features marked static objects, complete with Lightmap UVs, and is ready for lightmapping. The default settings for all Unity scenes and projects is not compatible with a full lightmap setup as we require, and so we must access the lighting settings. To do this, display the Lighting window by navigating to Window | Lighting from the application menu. Once opened, dock the free-floating window into the object Inspector as a separate tab. This is convenient because we can view the lighting settings and inspect the Scene viewport side by side.

Accessing the Lighting window

First, let's disable all precomputed GI settings, by removing the check mark from the Precomputed Realtime GI rollout in the Lighting window. This completely deactivates real-time GI for the scene. In addition, specify the night time skybox (created earlier) for the Skybox field. This is important for establishing a base, ambient lighting pervading the scene, even in the...

Having now established a resolution and Atlas Size, we should specify baking details to improve the quality and appearance of our lightmaps. To do this, enable Ambient Occlusion and tweak the Max Distance field until you get the volumetric effect desired. This requires rebaking. Ambient Occlusion is sometimes called Contact Shadows because it generates shadows where two or more solid bodies meet, such as the floor meeting the wall, or crevices and cracks. This creates a volume effect, enhancing the 3D-feel of a scene.

Enabling Ambient Occlusion

In addition, enable Final Gather. Set the Ray Count to 256. Final Gather reduces noise and improves the quality of lightmapping. Higher values result in smooth, higher quality output, at the expense of the calculation time.

Enabling Final Gather

Finally, you can increase the resolution of specific objects, if needed. We don't need this for DK, but if you have large, eye catching and very important objects in a scene (such...

The lightmap setup works well for the scene, but applies only to static objects; such as walls, floors, ceilings, and props. Animated and movable objects, such as NPCs, will by contrast continue to be illuminated by expensive dynamic lights, unless additional steps are taken. Let's take those now using Light Probes. They are special sampling objects, which should be positioned strategically around the scene to record an average of light color and intensity at that location. When multiple Light Probes exist, movable objects such as characters are illuminated by interpolated values taken from the nearest probes. Light Probes, therefore, record color and intensity, but they do not cast shadows. To get started with Light Probes, create a new game object to act as the parent of all probes. Navigate to GameObject | Create Empty from the application menu. Name this object LightProbes.

Creating an empty object for Light Probes

Next, add a Light Probe group component to the newly created...

This section takes time out to explore lighting issues and problems that sometimes arise and common methods for resolving them. The issues listed here may not arise for the Dead Keys project specifically, but it's likely you'll encounter them somewhere, on some projects. Consequently, it's good to know how the issues are solved or at least avoided. This section takes a Question and Answer format:

Disabling Auto for baking

Now it's time to explore NPC intelligence and, specifically, path finding. We'll need our NPC zombies to move around the scene intelligently; that is, to move without bumping into walls, floors, doors, and other obstacles, and without taking the most complex routes to nearby destinations. Our zombies must cleverly navigate their way around the environment, whatever its arrangement, finding their way toward the player to engage in combat, as though they really had brains! To achieve this, a navigation mesh is required. This is a nonvisible mesh asset, generated by Unity, to approximate the scene floor, for both exterior and interior environments. More accurately, it represents the total walkable floor of the scene-the area over which NPCs may maneuver for travelling from point to point. To access the navigation mesh features, click on Window | Navigation from the application menu. This opens the Navigation mesh window, which can be docked into the object Inspector.

Accessing...

Unity imposes no official limits on the size of your scene, and there's no established convention or industry-standard making recommendations about scene size. This is a decision largely in your hands. But there will certainly be a limit in a practical sense. The complexity of meshes, materials, and special effects combine together with the number of meshes and their spread to determine just how computationally expensive a scene is when presented to a camera with a specific frustum and field of view. Unity tries to make scene rendering easier on the computer by applying Frustum Culling automatically. That is, it silently deactivates (culls) objects outside the viewing volume (frustum) of the camera. As objects leave the frustum, Unity ceases to render them, and as they enter the volume Unity starts rendering them. This optimization works well in many cases, for objects that clearly enter and leave the Frustum.

Camera frustum defines the limits of what can be seen

Using...