Request for new primitives

[Peter Blomberg]

... do all parts of a primitive have to be visible?

The simple answer is: no, all parts of a primitive need not be visible. There are acceptable use cases where part of a primitive is obscured by other geometry. Avoid T-junctions where an edge of a non-visible surface goes along the surface of a visible surface as this creates optical flickering.

The more accurate answer would include considerations for minimizing/balancing the need for intersections with part complexity (number of lines required to create a particular geometry without intersections). If the part is transparent in any color, then superfluous interior surfaces should specifically be avoided as much as possible.