10 Mar
2008
10 Mar
'08
12:08 p.m.
On Mon, 10 Mar 2008 11:25:55 +0000, Roger Holmes wrote:
There are issues using 2Pi
because of rounding errors. Usually you end up having tolerance
values. Without tolerances, if someone rotates something by 90
degrees four times, they don't QUITE get what they started with when
using 2PI, but with degrees, they do.
Were are not talking about rotating an image here just projecting one.
As for representing an infinite number of angles,
don't be silly.
Especially if you are using tolerances.
Point taken :-)
You also pointedout corredtly that floating point hardware was not always available.
We were punching fixed-point CAD data on 80 col cards and plotting bed sheets on a
flatbead plotter, it
was "old" when I first worked with it in the mid 70's at Western Electric.
BTW: radians work fine with fixpoint provided you are not rotating things that were
previously rotated.
Back to topic, I think the subject was displaying tesx on a vector screen.
In the 1960's Dr. A.V. Hershey of the Naval Weapons Laboratory while working with the
U. S.. National
Bureau of Standards created the Hershey's Repertory of Occidental Type Fonts. This is
the origional data
set I used when I built the CADfont set for AutoCAD that became the extened font set and
package with
the product.
Over the years many conversions/translations have been made, somewhere around here I have
a copy
coded in (lisp) for driving a flame cutter. Check it out, and yes it is interger vector
based ....
Here is a google link for more info:
http://tinyurl.com/36un8h
Back under my rock ...
Bob