Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!mips!ptimtc!nntp-server.caltech.edu!toddpw
From: toddpw@nntp-server.caltech.edu (Todd P. Whitesel)
Newsgroups: comp.sys.apple2
Subject: Re: B-splines
Message-ID: <1991Jun6.110539.3665@nntp-server.caltech.edu>
Date: 6 Jun 91 11:05:39 GMT
References: <819@generic.UUCP>
Organization: California Institute of Technology, Pasadena
Lines: 25

ericmcg@pnet91.cts.com (Eric Mcgillicuddy) writes:

>What are Bsplines and how can they be drawn using Quickdraw II?

Bsplines are curves that are formed by parametric interpolation of a list
of "control points" -- if you have a list of points, and connect them in
order, you'll get a jaggy 'curve' with sharp corners and so on; draw the
set of Bspline segments specified by that same list of points and you'll
get a smooth curve shaped roughly like the jaggy one, as if the jaggy
curve had all its corners severely smoothed out.

No existing implementation of Quickdraw is capable of drawing Bsplines as
objects. The TrueType font engine might be able to do it, they are using
curves that should be a superset of cubic Bsplines (which is what most
people simply refer to as Bsplines).

I do have code examples but they would take a while to explain (they use
matrix operations to represent and evaluate the curve points), and I'm not
sure if I have a stable executable with the curve code in it that you can
run on a stock GS.

Todd Whitesel
toddpw @ tybalt.caltech.edu

P.S. do it quick, I leave in a little over a week.