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Mapping functions are used to apply two-dimensional textures to
surfaces. Each mapping functions defines a different method of transforming
a three dimensional point of intersection to a two dimensional u-v pair
termed texturing coordinates.
Typically, the arguments to a mapping method define a center of
a projection and two non-parallel axes that define a local coordinate system.
The default mapping method is termed u-v mapping or inverse mapping.
Normally, there is a different inverse mapping
method for each primitive type.
When inverse mapping is used, the point of intersection is passed to
the uv method for the primitive that was hit.

- map

uv
Use the uv (inverse mapping)
method associated with the
object that was intersected in order to map from 3D to determine
texturing coordinates.

- map

planar [^origin ^vaxis ^uaxis]
Use a planar mapping method. The 2D texture is transformed
so that its u axis is given by ^uaxis and its v
axis by vaxis. The texture is projected along the vector
defined by the cross product of the u and v axes, with
the (0,0) in texture space mapped to ^origin.

- map

cylindrical [^origin ^vaxis ^uaxis]
Use a cylindrical mapping method. The point of intersection
is projected onto an imaginary cylinder, and the location
of the projected point is used to determine the texture coordinates.
If given, ^origin and
^vaxis define the cylinder's axis, and ^uaxis defines
where u=0 is located.
See the description of the
inverse mapping method for the cylinder
. By default, the point of intersection is
projected onto a cylinder that runs through the origin along the z
axis, with ^uaxis equal to the x axis.

- map

spherical [^origin ^vaxis ^uaxis]
Use a spherical mapping method. The intersection point is
projected onto an imaginary sphere, and the location of the
projected point is used to determine the texturing coordinates
in a manner identical to that used in the inverse mapping method
for the sphere primitive.
If given, the center of
the projection is ^origin, ^vaxis defines
the sphere axis, and the point where the
non-parallel ^uaxis intersects the sphere
defines where u=0 is located.
By default, a spherical mapping projects points towards the origin,
with ^vaxis defined to be the z axis and
^uaxis defined to be the x axis.
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Next: Options
Up: Texturing
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Jelle van Zeijl (jvzeijl@iso.estec.esa.nl)
Wed Jun 15 16:19:08 MET DST 1994