Gena wrote:
> 
> In case of plug-in you should know just a plug-in subset of the whole 
> API. In case of patch you should learn the whole API and define where
> to fit your piece. In case of plug-in you are in sandbox, you still
> can destroy the functionality of the whole program but IMHO you have
> less changes than in case of patch :)

This is a fallacy, to link a new feature dynamically to the program 
won't give you any technical advantage.  And whatever API you are 
talking about this is no different when implementing a new feature in 
POV-Ray than as a separate module.

> 
> Got you. You are talking about custom patch.

I was talking about this all the time - as said i consider the 
possibilities for SDL based plant generators as very limited.

> Of course it will work but
> how many people can write POV-Ray patch? :) I would still prefer don't
> touch POV-Ray itself. In your scenario you use only mesh generator from
> POV-Ray the rest is patch itself. As you mentioned already mesh
> generation is not big deal. So the whole functionality can be
> freely implemented outside of POV-Ray.

Of course it can.  And the second possibility after a POV-Ray patch is a 
separate program.  The main reasons for implementing a plant generator 
in POV-Ray and not in a separate program would be:

- to avoid the need to parse the resulting mesh.  Note while this is an 
important point it is much smaller than the difference in performance 
between parsing a plain mesh and generating it with an SDL based plant 
generator.
- to be able to make the plant generation interact with the rest of the 
scene.
- to be able to use other POV-Ray features in the plant generation process.

Thinking a bit about it a well designed modular plant generator might be 
possible to work both as a POV-Ray patch (offering the above advantages) 
and outside (without those options).  This would probably not make the 
implementation easier but it would at least force a clean design. ;-)

> L-Systems, rules based systems are good to a certain extent. But when
> you need the whole control of the geometry it doesn't work. For example
> it doesn't work when you need the trunk pass through particular
> coordinates <0, 1, 0.3> etc.

This is not made impossible by a rule based plant generator.  The rules 
just have to force such constraints.  In fact i think rules are the only 
feasible possibility for geometry control with complex plants.

Christoph

-- 
POV-Ray tutorials, include files, Landscape of the week:
http://www.imagico.de/ (Last updated 31 Oct. 2005)
MegaPOV with mechanics simulation: http://megapov.inetart.net/

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