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ambient-whisper
05-04-2003, 04:14 AM
howdy. after watching a video on the creation of the Ents for lotr over at IGN, I noticed that weta made special tools to help them automate the process of making branches.. and trees.
in one shot they show the artist using a slider and the tree automatically updates with more branches.. when he decreases teh value of the slider the tree has less branches.
sofar my impression of mel seems that its only capable of taking commands and changing the values of certain properties like scale.. translation.. but how about the "COPY" property to do something like the Copy SOP in Houdini?

gmask
05-04-2003, 07:56 PM
Basically it sounds like they had a function that creates branches and the slider controls the number or branches and then brach function reads the input geometry and either places new "COPIES" based on exisiting CV's or somewhat randomly.

Once you have built these functions you can connect them together in a similair fashion as Houdini but Houdini is designed to be more visual and has many of these functions allready designed for you.

From my own experience with MEL I have found that it is often easier to program things by not making them so procedural but that each time you wish to contruct something and you change the parameters you delete the old contruct and simply build a new one. This may not allways be the best way to go about things but there is a lot of overhead in giving scripts interface and modularity and Houdini sort of does alot this for you out of the box.

jschleifer
05-04-2003, 08:01 PM
Heya,

this was probably a separate application you saw called "grove". It was built by our inhouse modelling supervisor, Matt Aitken.

-jason

gmask
05-04-2003, 08:10 PM
Originally posted by jschleifer
Heya,

this was probably a separate application you saw called "grove". It was built by our inhouse modelling supervisor, Matt Aitken.

-jason

I think I read about it somehwere?? did it start out as an L-system?

jschleifer
05-04-2003, 08:14 PM
I think (if I remember correctly, I'll have to ask him), he wrote it because it wasn't l-system based. He didn't like any of the l-system stuff available, so he wrote this method, but I don't know any more about it. I'm seeing him today on the flight to copenhagen, so I'll ask him then. :)

cheers!
-jason

gmask
05-04-2003, 08:20 PM
Originally posted by jschleifer
I think (if I remember correctly, I'll have to ask him), he wrote it because it wasn't l-system based. He didn't like any of the l-system stuff available, so he wrote this method, but I don't know any more about it. I'm seeing him today on the flight to copenhagen, so I'll ask him then. :)


Yeah.. I think because L-systems take up a huge amout of ram and perhaps were too slow.

From personally experience I know why you would not want to MELscript this in Maya because once you get into hundreds or thousands of iterations of geometry the program really slows down. I can only hope it would be better as a plugin.. or int his case a standalone application.

toysnob
05-14-2003, 09:50 PM
Does this mean L-Systems aren't really used for professional work in films or at least not in shots that require complex effects?

Is it a feature of Houdini worth learning (I realize L_systems predate Houdini itself), but I mean is it something that would be good to have in terms of employability as a procedural modeller/animator with Houdini as your main app?

sedric
05-14-2003, 10:57 PM
i dont mean to ask a silly question....but could one of you fellas explain what an L-system is? and why it is good/bad... it sounds kinda neat...


thanks fellas,

sedric

ambient-whisper
05-14-2003, 11:00 PM
its a branching system.trunk branches off...branches branch off. etc.
often used for stuff like trees/ flowers. etc.

mark_wilkins
05-15-2003, 07:36 PM
L-systems and their progeny are used all over the place in big film productions, but there are other ways to do the same things.

Doing this kind of thing in MEL, though, can be troublesome. What you really want to avoid is making a hundred thousand complete, separate geometry objects.

If you can use particle instancing, paint effects, or manipulating the contents of a small number of meshes or NURBS surfaces to get where you're trying to go, though, performance may not be that much a problem.

-- Mark

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