Game Development Reference
In-Depth Information
FIGURE 9.28
Follow the same steps to texture Grae. (See page C9 for color version.)
Working with an Alpha Map
In this section we will add transparent areas to the geometry by using an
alpha map
. An
alpha map is basically a grayscale image. This image tells Maya (or your game engine)
which parts of the texture page are transparent and which are opaque. In Maya, areas that
arepurewhite(values255,255,255inallred,green,andbluechannels)willrenderopaque;
black(0,0,0)willrendertransparent;andanyvaluesinbetweenwillbetranslucenttovary-
ing degrees. (Some game engines invert these values, so it's important to check with your
manager to verify the final opacity values.)
There are five regions in our two characters on which we can use an alpha map. For Kila,
we can implement alpha maps into her hair, eyes, and eyelashes. Grae only needs alpha
maps on his eyes and wings.
Creating the Hair Alpha Map
Let'slookatKila'shairfirst.Atpresent,herhairisquiteangular(
Figure 9.29
),andwecan
fix this by making the strands more transparent toward their ends, losing the sharp edges
that the polygons form.
