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Parametric NURBS Modelling in Ayam

This page describes some experiments with parametric NURBS modelling in Ayam while creating the Marsrakete image:


Since the image is rendered using a simple cartoon/cel shader, everything (yes, every rivet!) has to be pure geometry, no textures will help.
Luckily, in Ayam, you can do this easily with the help of the ExtrNC and Clone tool objects.
But let us have a look at the overall scene structure first:

The main body is a surface of revolution that depends on a curve, currently selected in the upper image. To create a wing attached to this surface, three curves are extracted, and, together with other curves, skinned (the flow of geometric information is shown by red arrows in the above image). Since the curve extraction only extracts curves over the full extent of the surface, small Script objects trim the extracted curves to the right length.
The wing is put into a Clone object to easily have any number of them. In addition, the advanced Gordon caps have an appearance (they close the non-planar wing surface as can be seen in the wing detail image):

Let us move on to the rivets, this time we are using the extracted curves as trajectory to place them on. Again, since the ExtrNC object only provides curves that extend over the full length of a surface, small Script objects trim the extracted curves to the right lengths.

Read on for some funny experiments with this model.

The original setup. Everything is parametric, i.e. the body shape depends on one single NURBS curve (currently selected in the upper image). The rivets and wings, in turn, depend on the body shape.

The main shape defining curve was modified, note how the rivets and wing automatically adapted.

More parametrics: the Clone object is in use to create the original four wings, but it can also easily create six of them...

Lets have more fun with the wings. Each wing is actually a Skin with three defining curves extracted from the rocket body and four more curves to define the shape of the wing in space (there are actually two more curves to close the Skin in u-direction; so that it is, topologically speaking, an open cylinder). The image above shows the original setup.

Modification of the four outer curves to achieve a different wing design.

More fun with the wings.

And now, get the scene file for your own experiments (yes, it is really just 5K).

Randolf Schultz, 29. Dec 2015