Object Texture Mapping
.P
Each object primitive which can be created in SIPP has an argument
that describes what kind of texture coordinates should be assigned to
the surface of the object. This parameter can have one of the following
predefined values:
- NATURAL - This value tell SIPP to use a two dimensional mapping
which `is "natural" for this particular object. It might be one of the other
available mappings or it might be something unique for the object. The
description of the functions for creating the individual objects specifies how
this mapping is done.
- CYLINDRICAL - A two dimensional mapping. The coordinates are
assigned as if the object were projected on a cylinder surrounding the object
and centered on the z-axis object. The coordinates are mapped so that x
goes from 0 to 1 around the base of the cylinder and y goes from 0 to 1
from bottom to top on it.
- SPHERICAL - Same as CYLINDRICAL, but the object are
projected on a sphere surrounding it instead.
- WORLD - A three dimensional mapping. The texture coordinates are
the same three dimensional coordinates as the world coordinates of the object
at creation time.