Game Development Reference
In-Depth Information
lighting. Similarly, sometimes mediocre work or simplistic design reads very
sophisticated due to some especially effective lighting schemes.
When teaching Maya by itself, I spend several weeks in class working through
lighting techniques as well as rendering technologies (Maya Software vs
Mental Ray vs VRay, etc.). In reality effective lighting is worthy of its own topic
and thus beyond the scope of this one.
However, it is important to see how Unity's lighting tools work—specifically,
how these lighting tools can be used to “bake” a lighting scheme onto the
textures that cover an object.
Baking
Baking
can refer to a lot of things in 3D. Animation can be baked. Physics
simulation can be baked. Cloth can be baked. And of course, lighting can be
baked. At its core, baking is the process of taking something that is calculated
dynamically (balls falling and colliding with objects in a physics simulation,
or cloth bending and deforming, or shadows being rendered on a surface)
and transferring that information into a static file that is inflexible (cannot
be changed without appending or rebaking) but very quick. So in Maya, a
complex cloth simulation that takes several seconds a frame to figure out, can
be baked down into something that plays in realtime.
In the case of lighting, baking is the process of taking the illumination a light
gives off (and more importantly), the shadows that objects cast on other
objects, and painting those adjusted color values on objects. Think of painting
cast shadows across a surface, and painting a tint on a surface that shows the
yellowish light of the dirty lamp post.
This is important because rendering lighting in realtime is an expensive
process. Video cards (even dedicated cards) have to expend a lot of cycles
and memory to make this happen. By baking the lighting in, the video card
is simply drawing a texture (or layered textures) and not having to draw
illumination and shadow passes.
Baking in Unity (aka Unity Lightmapping)
So why not Maya? Why not cover Maya's lighting tools and how to bake
in Maya? Good questions with some good answers. It can be a tough call
deciding what to do in Maya and what to complete in Unity, especially as
Unity increases its flexibility in level organization and movement. Previous to
Unity 3, Maya undeniably would have been the place to bake, but with the
new technologies in Unity 3, baking in Unity has some distinct advantages.
The first reason we won't be covering baking in Maya in this topic is because
there's a really nice Maya baking tutorial at
http://unity3d.com/support/
resources/tutorials/lightmapping-in-maya
; no need to replicate it here. Second,
lighting a scene and baking it in Maya usually means a whole lot of material
reconstruction once the asset is imported into Unity. Unity essentially brings in
