As I said in my original posting, I would not want to force people to
have to use units on dimensions - it would be optional.
Quote - "This would surely be a simple modification to the parser and
would still leave the ability for people to work in a 'unit-less' fashion if
they like?"

You said there is no difference between various units.inc - I beg to differ.
Sonya Roberts "Units" include file is not deployed with the POV Ray
installation as
far as I know, so tomorrow (lets say) I'm going to release onto the Web my
own
comprehensive version of units.inc which contains :-

#declare in = 1
#declare ft = 12
#declare cm = 2.51
etc etc etc

A box{ <0cm,0cm,0cm>,<1cm,1cm,1cm>} written against Sonya Roberts include
file will
translate into a 1 unit cube by povray and under my Units.inc it would
translate into a 2.51
units cube within Povray.    Therefore any object taken from a scene written
using the former
include file will need scaling if incorporated into one using the second.
The situation is made
worse if someone has not even used any units in the first place.   Or
someone may have defined
their own unit declarations.

All I'm saying it that -

a) It would be nice if people were encouraged to use (but optional)
dimensional units
in 'real world' modelling and in a standardised way.
b) The above would be encouraged by formalising the concept into Povray so
everyone knows
and works of the same definitions.
c) It would lead to greater readability of the source file.
d) It would mean it is easier to cut and paste objects from other peoples
files.

Alan Smith.



"ABX" <abx### [at] abxartpl> wrote in message
news:d1umkv8cb5ictbfnknmuumcl0mnoks54hk@4ax.com...
> On Tue, 26 Aug 2003 15:56:04 +0100, "Alan Smith"
<ala### [at] aurora-ukcom>
> wrote:
> > By encourage its use I mean that if it is a formally accepted concept
within POV
> > then people are more likely to know its there and more likely to use
it - especially
> > when they see the benefits of re-using other peoples objects without any
re-scaling
> > required.
>
> But on the other hand for many works you do not need units at all so they
are
> unnecessary typing. Do you need units to draw graph? POV-Ray is known to
be a
> tool in scientific works to visualize processess. Some sciences operates
on on
> units, some not. And soon you incorporate units into language you will
receive
> complaining why other units are not supported. It is easier to change
> units.inc than povray.exe
>
> > I did not know of the existence of Sonya Roberts "Units" include file
> > until you pointed it out - what if someone else out there defined
another "Units" file
> > which other people used - the definition of mm,cm,m,ft & in might be
totally different -
> > standardisation has not been achieved nor generally portability of
objects.
> > If I copy an object from someone's scene using an alternative definition
of the units
> > then it will not just drop in to mine and work - yes I know I could
scale it but that's
> > not the point.
>
> There is no difference between various units.inc - as long as they use the
> same letters for naming units and they preserve the same relations they
are
> compatible regardless base unit.
>
> ABX

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