Use Hedra to produce
objects from several families of polyhedra.
Watch a movie about the Hedra
Extended Primitive.
Procedures
To create a polyhedron:
 From the Create menu, choose Extended
Primitives Hedra.
 In any viewport, drag to define a radius,
then release to create the polyhedron.
As you drag, a polyhedron
emerges from the pivot point.
 Adjust the Family Parameter and Axis
Scaling spinners to vary the Hedra's appearance.
Interface
Family group
Use this group to select
the type of polyhedron to create.
 Tetra

 Cube/Octa

Creates a cubic or octahedral
polyhedron (depending on parameter settings).
 Dodec/Icos

Creates a dodecahedron or
icosahedron (depending on parameter settings).
 Star1/Star2

Creates two different starlike
polyhedra.
TipYou can animate between
Hedra types. Turn on the Auto Key button, go to any frame, and change
the Family check box. There is no interpolation between types; the
model simply jumps from a star to a cube or tetrahedron, and so on.
Family parameters group
 P, Q

Interrelated parameters that
provide a twoway translation between the vertices and facets of
a polyhedron. They share the following:
 Range of possible values is 0.0 through
1.0.
 The combined total of the P and Q values
can be equal to or less than 1.0.
 Extremes occur if either P or Q is set to
1.0; the other is automatically set to 0.0.
 Midpoint occurs when both P and Q are
0.
In the simplest terms,
P and Q change the geometry back and forth between vertices and
facets. At the extreme settings for P and Q, one parameter represents
all vertices, the other represents all facets. Intermediate settings
are transition points, with the midpoint an even balance between
the two parameters.
Axis Scaling group
Polyhedra can have as
many as three kinds of polygonal facets, such as triangle, square,
or pentagon. These facets can be regular or irregular. If a polyhedron
has only one or two types of facet, only one or two of the axis scaling
parameters are active. Inactive parameters have no effect.
 P, Q, R

Controls the axis of reflection
for one of the facets of a polyhedron. In practice, these fields
have the effect of pushing their corresponding facets in and out. Defaults=100.
 Reset

Returns axes to their default setting.
Vertices group
Parameters in the Vertices
group determine the internal geometry of each facet of a polyhedron.
Center and Center & Sides increase the number of vertices in
the object and therefore the number of faces. These parameters cannot
be animated.
 Basic

Facets are not subdivided beyond
the minimum.
 Center

Each facet is subdivided by
placing an additional vertex at its center, with edges from each
center point to the facet corners.
 Center & Sides

Each facet is subdivided by
placing an additional vertex at its center, with edges from each
center point to the facet corners, as well as to the center of each
edge. Compared to Center, Center & Sides doubles the number
of faces in the polyhedron.
NoteIf you scale the
axis of the object, the Center option is used automatically, unless Center
& Sides is already set.
To see the internal edges
shown in the figure, turn off Edges Only on the Display command panel.
 Radius

Sets the radius of any polyhedron
in current units.
 Generate Mapping Coords

Generates coordinates for
applying mapped materials to the polyhedron. Default=on.