Graphics Reference
In-Depth Information
Fig. 11.1 Shaders are applied to spheres to give an idea what they will look like when applied to
a model
hold out the promise of unifying the shader types used in both industries, but are not
in common use yet (McAuley et al. 2012 ).
The fi lm industry employs technical directors and shader writers specifi cally to
create specialty shaders for their productions. These shaders can include such things
as defi nitions for procedurally-generated geometry. Only recently is it possible for
video game developers to consider geometry shaders or real time ambient occlusion
(Lefohn et al. 2009 ).
Regardless of the type of shader used, textures can have a powerful infl uence on
the fi nal appearance of a shader (Fig. 11.2 ). This is because shaders specify global
changes within any given parameter. For instance, a shader can be assigned a single
color by adjusting a slider, but if it must have many colors, to show where they are
and what they are, a texture map is used instead to control local effects of the shader.
The quality that makes texture maps so important to shaders is that they can specify
different values at different locations within UV space. Procedural shaders are able
to do something similar, by using an algorithm to create certain types of textures,
like wood grain, but if the pattern desired does not conform to an easily defi nable
pattern, it must be defi ned manually, and that is where texture maps are used.
11.3
Specialty Shaders
Some subjects are inherently diffi cult to represent in 3D because of their great struc-
tural complexity. Hair, cloth, water, and plants all fall into this category. Artists who
work with these subjects cannot effectively model each of the elements required to
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