Dancing About Architecture

How do you draw a continuous tube?
Jun 2 1992, 8:28 pm
Newsgroups: comp.graphics,comp.graphics.visualization
From: ericl...@stokes.Princeton.EDU (Eric Matthew Lunt)
Date: Tue, 2 Jun 1992 23:42:25 GMT
Local: Tues, Jun 2 1992 4:42 pm
Subject: How do you draw a continuous tube?

Hello there. I've got a graphics problem that isn't getting any
easier the more I think about it. I am programming on a Silicon
Graphics machine using the SGI GL.

I am currently drawing a continuous line in 3D that is made up of
short, smoothly varying segements (i.e. no sharp corners). These
represent 3D streamlines in my program. Now what I want to do is
instead make a "tube" by defining a series of cylinders with a
variable radius at each vertex. What I am having problems with is
connecting each cylinder to the previous one at each vertex so it
appears continuous.

The only solution that I have thought of is to manually calculate the
points on the plane that bisects the two normal planes to the vectors
that define each segment. I'd much rather use the SGI coordinate
transformation commands on a unit cylinder, but I can't see how to.

I'd appreciate any suggestions/war stories that you all might have.

/***********************************************************/
/* Eric Lunt ericl...@acm.princeton.edu */
/* ericl...@phoenix.princeton.edu */
/***********************************************************/

For what it's worth, I never really found the answer.