Bernd Fuhrmann <Sil### [at] gmxde> wrote:
> >   Transform to what?

> POVXML(with a lot of extensions) -> POVXML(with fewer extensions) -> 
> POVXML(with no extensions) -> POVRay SDL -> BMP

  So what you want is a *separate* application which converts your
pov-XML to SDL and then uses POV-Ray to render the image?

  Then why not just go ahead and create such XML specification? Let's see
how much people will be using it...

> >   You have to still remember that the SDL is a programming language, not
> > a document.

> What's the difference?

  By definition in a markup language you have to tell for each distinct
item its type (in XML in the most cumbersome way with starting and
ending tags). An XML parser can then do something with each type
according to some specification of how each type should be interpreted.

  In a programming language you don't need to specify the type of
each item which appears in the program source code. This is because
a programming language is typically not designed so that it can be
parsed with a generic markup parser but needs a parser specific to
that programming language. The advantage of this is, naturally, that
it makes it easier for the user to write programs using this language
because it's the language parser which performs the task of tokenizing
the input, not the user.

  If you write XML by hand you are burdened with this extra task which
should be something the parser does.

  Besides, being a very generic markup language which does not offer
anything specific to any programming language, most programmatical
constructs need to be done either with extremely bloated syntax
where you (not the parser) tell the program for each single item
what it is, or either you use a very artificial syntax of putting
the whole thing into a string (which you should not be required to do
in the first place; just the fact that the quotation marks and other
extra syntax around these strings are not part of the expression should
immediately give you a hint that there's something unneeded there).

  In a programming language you say typically: a=b;
  Now, just think about how you would do that same thing in XML and
how much of that line will be additional bloat which is not really
part of the command but is required by XML. Also think why the user
should write that extra stuff when there's no need.

  The user and the program (in this case POV-Ray) are not interested
in the markup of the input, they are only interested in its meaning.
It just doesn't make any sense to force the user to specify any
markup on the input since none is needed for anything.

> XML offers all these things in one standard that many people know of.

  Can't you understand that XML is not the right tool for writing a
program? Programs are usually written by hand, and this task should be
made as easy as possible.

  What you are suggesting is making the life of the users harder in order
to make the life of the programs easier.

> <sphere center="0,0,0" radius="5"/>

> compare this to:
> sphere {<0,0,0> 5}

  Why should the user be burdened with all that additional syntax?
What does it benefit the user that he is forced to write all those
extra symbols and keywords?

  Besides, that extremely simplistic example is too naive. How would
you write this in XML so that it makes the life easier for someone
(for the user, or the parser, or the renderer or anyone):

union
{ #declare IndX = 0;
  #while(IndX < MaxX)
    #declare IndY = 0;
    #while(IndY < MaxY)
      sphere
      { <IndX*5+1, IndY*0.25-1.25, -5>, IndX*IndY/10
        #if(IndX < MaxX/2)
          pigment { rgb <IndX/MaxX, IndY/MaxY, 0> }
        #end
      }
      #declare IndY = IndY*.125;
    #end
    #declare IndX = IndX*.5;
  #end

  pigment { rgb x } finish { specular .5 roughness .03 }
}

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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