## Polygon Surfaces

mental ray supports input of surfaces defined by
polygonal geometry. In the general case
it allows to specify a list of arbitrary polygons (convex or concave) with
optional holes using any number of vertices and edges. The polygons may be
connected by shared vertices to form a mesh. Materials can be
assigned to the whole mesh or per polygon. It is possible to attach any kind
of extra data on a per vertex basis, like texture coordinates or user values.
The source description of polygon surfaces is subject to tessellation
and displacement for rendering.

### Tessellated Geometry

Many applications perform all steps of modelling operations down to the
creation of surface geometry including final tessellation for rendering engines.
mental ray supports direct input of such tessellated geometry into its scene
database as primitive lists, which avoids
additional efforts for storage and tessellation of typically large intermediate
data. For convenience, this type of geometry also supports sub-pixel
displacement during rendering, which further tessellates the input faces
as needed.

Copyright © 1986, 2013
NVIDIA Corporation