POV-Ray : Newsgroups : povray.binaries.images : Ivy Generator : Re: Ivy Generator Server Time: 25 Sep 2020 16:44:01 GMT
  Re: Ivy Generator  
From: hobBIT
Date: 4 Jul 2009 16:22:21
Anthony D. Baye schrieb:
> Plants will grow towards a light source, it's called phototropism (which I
> learned about a long time ago and never thought to find a use for).  you'll find
> that in a dark room with light coming through a hole in the ceiling, vines will
> grow along the floor toward the light, and will generally try to find the hole
> in the ceiling. Perhaps your model could account for the direction of the light
> source as well.  It would be a matter of weighting the probability of a split in
> a given direction by the amount of light in that direction or the probability of
> reaching light by growing in that direction.
> Otherwise, I think it's excellent work, and I wonder if it could be applied to
> other plant life, like trees and shrubs.
> Are you predetermining the starting location, or is it random?
> A.D.B.
> "Thomas de Groot" <tDOTdegroot@interDOTnlANOTHERDOTnet> wrote:
>> "Christian Froeschlin" <chr### [at] chrfrde> schreef in bericht
>> news:4a4e1f30$1@news.povray.org...
>>> Also, there is a lot of ivy on top of the objects while the
>>> walls are more thinly covered. I'm no expert on ivy but this
>>> seems a bit odd (but probably it just needs more starting
>>> points to cover a wall).
>> In some way, real ivy seems to concentrate on the top of walls/objects,
>> maybe because sunlight is stronger there. At least, that is what I observe
>> in my garden, so the ivy generator is doing a good job :-)  Thomas Luft's
>> generator shows exactly the same phenomenon.
>> Thomas

At the moment, growing is weighted by 4 factors:
1. follow direction of last segment
2. random
3. gravity
4. "up",
while the last can be seen as growing towards light. It's easy to add 
another weight which grows to a given vector, but growing to "light" can 
be very complex, depending on scene complexity, maybe a path can help 
out to accomplish this.

The starting point and primary growing direction are input parameters.

I think about a total replace of the current growing algo, as it always 
clamps to any object, so hanging ivy is not really possible atm.


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