GroIMP provides a set of geometric objects like spheres, cones
and boxes by means of specific node classes. The distinction between
these classes and turtle commands is somewhat artificial and mainly
due to historical reasons. The geometic objects can be found in the
Java package de.grogra.imp3d.objects, a full list
is contained in the online documentation located at
https://javadoc.grogra.de/imp3d/de/grogra/imp3d/objects/package-summary.html. The following
table gives an overview of some of the available geometric objects.
Table 2.3. Geometric objects
| Object | Meaning |
|---|---|
Sphere(r) | Sphere of radius r |
Box(z) | Box of length z and base
1 × 1 |
Box(z, w, h) | Box of length z (z-extension),
width w (x-extension)
and height h (y-extension) |
Cylinder(z, r) | Cylinder of length z (in z-direction)
and radius r |
Cone(z, r) | Cone of length z (in z-direction)
and base radius r |
Frustum(z, r, t) | Frustum of length z (in z-direction),
base radius r and top radius t |
As for the turtle commands, the listed geometric objects can be used in the specified form as patterns on the left hand side of a rule. E.g., it is possible to write
Sphere(r) ==> Sphere(r*2);
In addition to these basic geometric objects, GroIMP provides features for advanced geometry such as the construction of smooth spline surfaces. These features will be described later.