Game Development Reference
In-Depth Information
Note
Of course, you will need to check whether the game engine can handle
specularity and bump maps. Secondly, you must verify that you have the
texture space available for these effects. Each added effect will add anoth-
er version of the texture page to the overall texture page count.
Bumpmapsareusedtogiveobjectstheillusionofhavingevenmoredetail.Thebumpmap
uses a grayscale height map that works with the surface normals of the model. This map
tells us which areas on the texture need to be bumpy, and the normals tell the map what
direction to work in. This technique does not add any geometry to the model, and the sil-
houette stays the same.
The
specular map
simply specifies which areas of the texture are shiny and which ones
have a matte finish. It does this by producing a central hotspot and the halo surrounding it;
together, they provide an illusion of reflected light.
In much the same way as an alpha map, bump and specular maps work off a grayscale im-
age. White areas indicate higher bumps or shiny areas; darker areas create recessed areas
or matte areas. As described earlier for alpha maps, the values for black and white may be
inverted in some game engines; be sure to check this out.
Now let's explore briefly how we can implement bump and specular maps into our charac-
ters, while also seeing how to apply them in Maya.
Grae's Texture Effects
For a change, we will look at Grae first, because he will benefit more from these effects.
His skin is quite bumpy, and in lots of areas the flesh is torn away to reveal muscle under-
neath. By applying a slight shine to this muscle, we can give the impression of moisture.
Use the main textures as a guide when creating your bump and specular maps. Working
from these will help you to see which areas need to be shiny or how to judge the heights
for the bump map.
For the bump map, begin with a 50% gray background. This will allow you to add darker
colors to act as recessed areas on the character, as well as lighter areas to create bumps.
Figure 9.44
showsthespecular(top)andbumpmaps(bottom)wewillbeapplyingtoGrae.
You can find the completed maps on the CD in Project Files/09. Look for the files with
_Bump or _Spec at the end of the filenames.
