Game Development Reference
In-Depth Information
tutorials, the assumption is that you are familiar with the basic Maya tools
(Move, Scale, Rotate) as well as how to select component parts (vertices,
edges, faces). If you don't understand these concepts, it will be worth your
while at least to watch the introductory videos that are included with your
Maya installation.
A Bit of 3D Theory
Although we assume you know something about Maya's tools, it will
be vital that the basic theory of 3D is understood. Without this baseline
understanding of how digital 3D works, it will be impossible to appropriately
construct assets to be used in a game framework.
Figure 2.1 shows the anatomy of the polygon—the building block of 3D. The
main form that we think of as a polygon is referred to in Maya as a face . The
face is what the video card (and thus we) “see.” The face's shape is editable by
the components that surround it. The face is surrounded by edges that are
joined by vertices (singular form is vertex ). Most of these sorts of concepts
are covered in some form of junior high geometry; the one other important
concept and part of a polygon is the normal . The normal defines the front of
the polygon. In Figure 2.1 , this is indicated by the green line coming right out
of the middle of the face. Understanding that faces have normals is important
since most game engines save processing power by only drawing the front of
a polygon. If the camera is behind the polygons (if the normal is facing away
from the camera), the polygon is invisible.
Three-dimensional forms in a 3D application are created when collections of
polygons are put together. Think of polygons as unbending sheets of metal.
Where the sheets of metal connect can hinge, but the polygon itself cannot.
This means that the more polygons present, the more places the mesh can
bend, and thus the more complex the form can be. Take a look at Figure 2.2 to
see how a form goes from six polygons to 32 polygons to 100 polygons, and
the resulting forms that are possible.
Forms that are seen in a 3D environment are drawn by the video card in your
computer via a rendering engine of some sort. The rendering engines see
shapes by recognizing polygons. To be more specific, most rendering engines
actually see only triangular polygons (sometimes called tris ). There are several
ways to construct these tris; Maya's techniques include NURBS, Subdivs, and
straight polygonal modeling. All of these are different methodologies of
Figure 2.1 Anatomy of a polygon.
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