In article <41d86f9a$1@news.povray.org>, Darren New <dne### [at] sanrrcom> 
wrote:

> Once you get to the point of *interpreting* what "#while" means, you're 
> past the parsing stage. POV-Ray may call that "parsing", but it isn't. 
> It's executing the specification. In other words, if the OP wants to do 
> something like add a namespace to some selected number of variables, you 
> don't have to understand a "while" loop to find all the variables you're 
> going to change, any more than emacs needs to understand SDL to 
> search-and-replace spheres with something else.

When POV says it's parsing, it's really parsing. POV executes the scene 
file as it parses it, rather than parsing into an intermediate form to 
be executed later. This is one of the reasons it is so slow, and one 
thing which badly needs improvement in POV4...it crawls around the input 
source files while generating the scene. The body of a loop is actually 
parsed once per iteration. Then there's a postprocessing stage where 
stuff like photons and radiosity are precalculated, basically "filling 
in the blanks" of the generated scene, and then you get to the rendering 
stage.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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