On Wed, 06 Dec 2000 17:14:17 -0500, Chris Huff <chr### [at] maccom>
blathered:

>Well, I can't help with the macro, but threads are usually done with 
>either a triangle mesh, a CSG with lots of small objects chopping away 
>at or adding to a larger one in a spiral, or by using the parametric or 
>isosurface objects in MegaPOV.
>
Threaded objects I'm building need to be part of CSG objects.  So this
rules out meshes.  CSG could be ok, that's what I've been trying with.
(just my clumsy coding may be the problem...)  

>Using a parametric or isosurface would be the most memory efficient 
>method, and can give smooth results. They can be slow, but that wouldn't 
>be a problem unless the threaded part covers a large area of the final 
>image.
>
Isosurface sounds promising, I'm already using an isosurface supplied
by David Wilkinson for the expanded steel parts.

>It can be hard to get smooth shapes with the CSG technique, you have to 
>use a large number of shapes to get it right, and it can be slow and 
>memory consuming.
>
This is part of why I gave up on my attempts so far...test renders
taking forever...

>Meshes could be pretty fast and could be generated automatically with a 
>macro, but can have visible "facets" if you don't use a high enough 
>resolution, and can't be used in CSG (using CSG with meshes works in 
>MegaPOV, but it isn't very reliable yet). Though they can use a lot of 
>memory, copies of a mesh can use very little additional memory, because 
>they can share data. Because screws and bolts have a very repetitive 
>shape, a macro could make a basic "thread" shape like a short segment of 
>a bolt, and use groups of these scaled and translated to make the actual 
>screws/bolts very efficiently. That way, there would only be one basic 
>"building block" that all the bolts in the scene could be constructed 
>from, possibly saving a lot of memory.

Like I said above...need to be able to put them in CSGs...bummer...



Defective O-O

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