I'm currently working on a project that will require a number of strategically
placed trees and other plants. The problem I'm having is that, though there are
a number of macros and utilities to create organics for import into POV, some
with very good results; the mesh objects, once imported, tend to interfere in
ghastly ways with my scene geometry.

Might it be possible, in some future version of POV to have parametrized
plant-life objects in the SDL itself?  I would very much like to place a tree
at a given location and have it grow at that spot without passing through local
objects.

I have some idea that this would not be an easy task, but an informed opinion
would be appreciated.

A.D.B.

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"Anthony D. Baye" <Sha### [at] spamnomorehotmailcom> wrote:
> Might it be possible, in some future version of POV to have parametrized
> plant-life objects in the SDL itself?  I would very much like to place a tree
> at a given location and have it grow at that spot without passing through local
> objects.
>
> I have some idea that this would not be an easy task, but an informed opinion
> would be appreciated.

I would be very much surprised to see such a thing "natively" in POV-ray;
however, there's reason to be optimistic that POV-Ray 4.0 will come with a
scripting language powerful enough to realistically allow for plant growth
macros to be implemented in it; sort of "smart plants", so to speak - something
along the lines of that famous Ivy Generator running in POV's SDL.

Theoretically, such things could be implemented in the current SDL, too - but
you don't want to wait for parsing *that* long I guess :P

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Anthony D. Baye wrote:
> I'm currently working on a project that will require a number of strategically
> placed trees and other plants. The problem I'm having is that, though there are
> a number of macros and utilities to create organics for import into POV, some
> with very good results; the mesh objects, once imported, tend to interfere in
> ghastly ways with my scene geometry.
> 
> Might it be possible, in some future version of POV to have parametrized
> plant-life objects in the SDL itself?  I would very much like to place a tree
> at a given location and have it grow at that spot without passing through local
> objects.
> 
> I have some idea that this would not be an easy task, but an informed opinion
> would be appreciated.

POV-Ray is a renderer, not a modeler.

The SDL is for getting objects into the scene.  The logic for 
determining what should be in the scene should be coded into the .INC 
file using the SDL.  Adding the capability for the SDL to create models, 
above and beyond declaring primitives, makes the application more 
complicated, and the opinion of the POV-Ray developers (if I understand 
them) is that adding capabilities that can be done with the SDL is only 
worthwhile if the renderer can do them far more efficiently.  With what 
you suggest above, that is not the case.

That being said:

What you want is a system for representing areas which are already 
occupied, and thus which should exclude overlapping objects.  There are 
a number of simple solutions, and there are a number of efficient 
solutions, but no solutions which are both efficient and simple.

Regards,
John

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"Anthony D. Baye" <Sha### [at] spamnomorehotmailcom> wrote in message
news:web.4a392bafc3d6106c231d6f4b0@news.povray.org...
> I'm currently working on a project that will require a number of
> strategically placed trees and other plants. The problem I'm
> having is that, though there are a number of macros and utilities
> to create organics for import into POV, some with very good
> results; the mesh objects, once imported, tend to interfere in
> ghastly ways with my scene geometry.

By 'interfere' I take it that you mean that the plants grow through other 
objects in your scene. One very simple approach to resolve this is to use a 
CSG 'difference' operation with the generated vegetation to slice away 
offending foliage. The best results can be achieved by defining shapes 
specifically to 'trim' the generated objects, rather than using scene 
objects themselves. The prism object can be handy for this sort of thing, 
for example, creating a clearing or a path through a forest.

You also need to make sure you don't root a tree or a plant too close to the 
cleared area, otherwise you can end up with unsupported branches. This can 
usually be readily accomplished within the macro or algorithm you use to 
position the objects on the surface.

> Might it be possible, in some future version of POV to have parametrized
> plant-life objects in the SDL itself?

As you've noted, there are already macros that generate parameterized 
plant-like objects in the SDL itself (so no import required). Clipka 
mentioned the Ivy macros, there is also TomTree by Tom Aust which generates 
quite an impressive range of trees and shrubs directly using a wide range of 
variable settings. There's even a Java utility application (POV-Tree by Gena 
Obukhov) to generate the parameters required, or to generate mesh-based 
trees as POV-Ray include files.

The range of potential organic forms needed to emulate plants in detail 
would be huge and it doesn't seem quite right to me that POV-Ray itself 
would incorporate specific detailed real-world objects.  On the other hand, 
the POV-Ray Object Collection is intended to contain specific objects and 
generic macros written using POV-Ray SDL and distributed under a common 
license that would enable them to be shipped alongside POV-Ray in the 
future.

> I would very much like to place a tree at a given location and have it 
> grow
> at that spot without passing through local objects.

This final point could touch on collision detection, which POV-Ray doesn't 
really do, although you can achieve some crude forms of collision detection 
using the built-in 'trace' function that enables you to 'grow' things round 
an object rather than passing straight through them.

Regards,
Chris B.

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"Chris B" <nom### [at] nomailcom> wrote:
> As you've noted, there are already macros that generate parameterized
> plant-like objects in the SDL itself (so no import required). Clipka
> mentioned the Ivy macros,

Well, as a matter of fact I was thinking about Thomas Luft's standalone "Ivy
Generator" tool, which takes an .obj file to grow ivy around aribtrary geometry
and then export the plant as another .obj.

I wasn't aware there is such a thing as an SDL Ivy macro.

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"clipka" <nomail@nomail> wrote in message 
news:web.4a3a27155cdc3612e01952250@news.povray.org...
> "Chris B" <nom### [at] nomailcom> wrote:
>> As you've noted, there are already macros that generate parameterized
>> plant-like objects in the SDL itself (so no import required). Clipka
>> mentioned the Ivy macros,
>
> Well, as a matter of fact I was thinking about Thomas Luft's standalone 
> "Ivy
> Generator" tool, which takes an .obj file to grow ivy around aribtrary 
> geometry
> and then export the plant as another .obj.
>
> I wasn't aware there is such a thing as an SDL Ivy macro.

Ah. ok. I'd seen Ivy in images on p.b.i. back in March and assumed it was a 
macro.

Well for other examples you may need to go back to circa 2000, when people 
were using POV-Ray to create real-world photorealistic scenes from scratch, 
for things like Trees.inc and Giles Trans' MakeTree macros, which did both 
trees and shrubs. I think they're still available, though I've not tried 
them on the latest version of POV-Ray.

Regards,
Chris B.

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