POV-Ray : Newsgroups : povray.advanced-users : need help with threads (for bolts & such) Server Time
23 Dec 2024 22:41:17 EST (-0500)
  need help with threads (for bolts & such) (Message 1 to 5 of 5)  
From: Defective
Subject: need help with threads (for bolts & such)
Date: 6 Dec 2000 14:01:39
Message: <c03t2ts9rc1r7ar0n3f5deje6aoh5pkmmb@4ax.com>
Somewhere, long ago, I seem to recall seeing a macro for creating
threads.  Now that I'm working on something with threaded parts, I
can't find it and my own attempts at threading just don't work.

Anybody have some ideas?



Defective O-O

http://members.home.com/redundant/Defective/
(yes, I know that's the wrong membername...ran out of space at
http://members.home.com/defective/)


Post a reply to this message

From: Ken
Subject: Re: need help with threads (for bolts & such)
Date: 6 Dec 2000 14:13:08
Message: <3A2E9090.613232D7@pacbell.net>
Defective wrote:
> 
> Somewhere, long ago, I seem to recall seeing a macro for creating
> threads.  Now that I'm working on something with threaded parts, I
> can't find it and my own attempts at threading just don't work.
> 
> Anybody have some ideas?

http://www.ica.uni-stuttgart.de/~marc/bolts.html
http://www.ica.uni-stuttgart.de/~marc/nuts.html

-- 
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/


Post a reply to this message

From: Chris Huff
Subject: Re: need help with threads (for bolts & such)
Date: 6 Dec 2000 17:13:31
Message: <chrishuff-398EA9.17141706122000@news.povray.org>
In article <c03t2ts9rc1r7ar0n3f5deje6aoh5pkmmb@4ax.com>, Defective 
<def### [at] homecom> wrote:

> Somewhere, long ago, I seem to recall seeing a macro for creating
> threads.  Now that I'm working on something with threaded parts, I
> can't find it and my own attempts at threading just don't work.

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.

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.

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.

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.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><


Post a reply to this message

From: Defective
Subject: Re: need help with threads (for bolts & such)
Date: 7 Dec 2000 03:57:30
Message: <k0ku2t8ggo8c4k1hpde3390fcj5i4lp6rb@4ax.com>
On Wed, 06 Dec 2000 11:16:32 -0800, Ken <tyl### [at] pacbellnet>
blathered:

>http://www.ica.uni-stuttgart.de/~marc/bolts.html
>http://www.ica.uni-stuttgart.de/~marc/nuts.html

hhhmmm...

Looks promising...gonna download those & see how well they work.  With
luck, I can eliminate the head and make threaded rod too...

Thanks


Defective O-O

http://members.home.com/redundant/Defective/
(yes, I know that's the wrong membername...ran out of space at
http://members.home.com/defective/)


Post a reply to this message

From: Defective
Subject: Re: need help with threads (for bolts & such)
Date: 7 Dec 2000 04:08:21
Message: <q5ku2tofjd2okpfkl8jbee3ncmrt5k21kt@4ax.com>
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

http://members.home.com/redundant/Defective/
(yes, I know that's the wrong membername...ran out of space at
http://members.home.com/defective/)


Post a reply to this message

Copyright 2003-2023 Persistence of Vision Raytracer Pty. Ltd.