Game Development Reference
In-Depth Information
Materials
Texturing a model is not enough to bring it to life. As we said, textures represent the
visual aspect of a 3D model and generally, don't take into consideration the way light
interacts with the surface of the model.
To make a 3D model look nicer, it is also important to represent the way light interacts
with its surface. A vest doesn't reflect light as a metal weapon does, for example. As
we said in
The game artist
section in
Chapter 2
,
The Mobile Indie Team
, to recreate
the interactions of light with the surface of a mesh, artists make use of assets, called
materials.
A material is a collection of data that define both the generic visual aspect of a model
and the way its surface interacts with light.
A material is usually a collection of at least two maps. The first map is the texture of
the mesh and the second is the bump map, a black and white texture that defines
where the surface is concave and where it is convex. With just two such maps, the
look of a 3D model can definitely be improved.
Bump mapping is also a technique that saves system memory for a 3D model, redu-
cing the number of required polygons to make it look like it is actually modeled.
Let's take the example of the wall texture displayed previously. By adding a bump
map to the material of the wall, as we said, it is possible to fake the concaveness
and convexity of the wall.
You first model the wall as a flat parallelepiped (a three-dimensional figure formed
by six parallelograms). Then you create a material for the wall, which makes use of
