On 12/23/2012 12:19 PM, Kene Meniru wrote:
Hello: I am writing a program that is made up of a collection of
POV-Ray macros. POV-Ray is available at povray.org. It is a
ray-tracing program that reads a scene description language (SDL) to
create photo-realistic images. At this time my program (for modeling
building information) is so huge that I am finding it difficult
managing the macros and I am not even near completion.
I am hoping to move this program to python and am wondering the best
way to approach this.
I would like to model my program after LaTeX. Basically the user
writes a text file using certain key words and numbers and my python
program reads this file, calls the classes that will then work
together to calculate the information that is needed to create an
accurate model. The result of this calculation will be an output to
another text file in the appropriate format such as POV-Ray SDL,
OpenSCAD script, etc. This file output can then be rendered by the
corresponding program to produce the actual 3D model. The macros I
have now currently does this but like I said it is getting tedious
and most importantly the fun factor is losing its strength for me.
I have been advised to check out python-ply and I have come across
others. I have not really tried any yet and before I dive into any
one of them I was wondering what else I should know. The following is
a sample of what the text file that will be processed by this
proposed system will contain. I appreciate any pointers and
suggestions.
Mine is "Don't do that." Seriously. What I understand is that you are
proposing to design and write a parser for yet another Domain Specific
Language -- that will require knowledge to use that is useless outside
the specific domain. I expect that is will come to duplicate the basic
facilities of existing languages. Users will want to be able to
calculate, make conditional calculations and constructions, iterate*,
and define functions (subroutines, macros). Why bother to reinvent all
that? It often becomes a mess. (Or you will offer or people will want to
mix Python with the dsl. That also can become a mess.)
Instead, write a pypovray package incorporating the POV macros, that can
be imported into a python program. Write a tutorial for the specific
parts of Python that users will need.
For instances, someone wants to place duplicate or parameterized models
on a rectangular grid, along an arc, or even at random locations.
------------possible user file content for parsing ------------ // in
the following the python interface program reads //+ the contents of
the file "other.file" as if its content //+ were located at this
point.
# this is a python comment. trivial difference from //
include other.file
import other.file # with Python's variations
# or
exec(open('other.file')) # but it is nearly always better to
# keep the separate namespace. What if a name in other.file
# is the same as used below?
import pypovray as ppr
//In the following the python interface makes "snap_size" a //+
global parameter
> declare snap_size = 10
snap_size = 10 # the extra word is just noise
// In the following "buildingLevel" is a class that is //+ called
and passed the parameters in parenthesis. buildingLevel("FirstLevel",
3000)
// In the following "snapOffset" is a class that is //+ called and
passed the parameters in parenthesis.
snapOffset("Closet-S1_r1", "Closet-S2_r3", <0,0,0>)
Already legal Python
# at the end of the file
ppr.run(args)
# Reads globals(), which python has nicely created for you, to create
the master scene description and output whatever is needed for povray.
It could be part of a template.py file you provide.
--
Terry Jan Reedy
--
http://mail.python.org/mailman/listinfo/python-list
