Whoops, sorry for late reply, got caught up with HDRs :)

"Chris B" <nom### [at] nomailcom> wrote:
> "Bill Pragnell" <bil### [at] hotmailcom> wrote in message
> news:web.4a1e750b99a5bfb66dd25f0b0@news.povray.org...
> >
> > ... can you handle e.g. coiling automatically?

> I've added a bit more into the spiral macro. What d'you have in mind by
> coiling 'automatically'?

I meant 'loose' coiling, where the rope can pile up on itself, or a hanging
loose coil (hooked over something, for example). I realise these are
non-trivial, I expect people can model this manually given your tools - just
wondered, that was all! :-)

This is a great macro, keep it up!

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"Chris B" <nom### [at] nomailcom> wrote in message 
news:4a1e679e@news.povray.org...
> I'm working on a new Rope macro to handle knots and track object surfaces

I've posted the first version of these macros onto the POV-Ray Object 
Collection at:
http://lib.povray.org/collection/rope/chrisb%201.0/rope.html

This image shows the predefined styles you can use. It's easy to add your 
own styles and fairly easy to add new types of knot etc.. I'd be happy to 
incorporate any new styles or new knots that you develop into a future 
version.

Chris B.

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"Bill Pragnell" <bil### [at] hotmailcom> wrote in message 
news:web.4a2631e799a5bfb66dd25f0b0@news.povray.org...
>
>> > ... can you handle e.g. coiling automatically?
>
>> What d'you have in mind by coiling 'automatically'?
>
> I meant 'loose' coiling, where the rope can pile up on itself, or a 
> hanging
> loose coil (hooked over something, for example). I realise these are
> non-trivial, I expect people can model this manually given your tools - 
> just
> wondered, that was all! :-)
>

Here's an example of what the randomisation options can do with a bit of 
fiddling around. Some of the random shapes looked unrealistic, so it was a 
question of repeatedly adjusting the seed until I got reasonable looking 
shapes. This doesn't use any form of collision detection, so eagle-eyed 
observers will notice that some bits of rope pass through other bits of rope 
and even into adjacent objects in places.

The foreground object uses a very high randomisation setting at about 30 
times the default. The other two are copies of the same coil at about 15 
times the default randomisation (the one on the post is rotated and scaled 
down a little).

To really overlay the coils of rope so that you don't get collisions would 
be more complex. I've had a few ideas, but I'm not sure how difficult any of 
them would turn out to be to implement. Most of my ideas to date would risk 
ending up with some very limp-looking rope.

Regards,
Chris B.

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"Chris B" <nom### [at] nomailcom> wrote:
>
> I've posted the first version of these macros onto the POV-Ray Object
> Collection at:
> http://lib.povray.org/collection/rope/chrisb%201.0/rope.html
>

Thanks for making this macro available. I've just read the (extensive)
documentation and it's looking very useful. On my To Do list for my "Rock The
Boat" scene is still adding a rope for mooring the boat, and it seems that
these macros will do the trick perfectly :-). I still need to finish my own
damage macros first, but then I will definitely give your rope macros a go.

Cheers,
Erwin

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Hi Chris,

this is Sven. I really like your rope macro, and want to use it immediately 
for some of my scenes. Please send it to my e-mail address, I would be 
extremely happy.

Sven

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"Sven Littkowski" <Sve### [at] Jamaica-Focuscom> wrote in message 
news:4a30135d$1@news.povray.org...
> Hi Chris,
>
> this is Sven. I really like your rope macro, and want to use it 
> immediately for some of my scenes. Please send it to my e-mail address, I 
> would be extremely happy.
>
> Sven

Hi Sven,

It's on the POV-Ray Object Collection at:
http://lib.povray.org/collection/rope/chrisb%201.0/rope.html
There should be a download button at the top of that HTML page.

If that fails you should be able to download using the JavaScript-free index 
page at
http://lib.povray.org/searchcollection/index2.php


If you still have a problem downloading it let me know and I'll get you a 
copy somehow :-)

Regards,
Chris B.

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"Eriban" <pov### [at] spamgourmetcom> wrote:
> I still need to finish my own
> damage macros first, but then I will definitely give your rope macros a go.

Hi Chris,

I just thought I'd share my first results of using your rope macro. Attached is
an image with the result. To create the hanging loops I created a small macro
of my own. I still need to clean it up a bit and make it a bit more general,
but then I'll share it.

I still have a problem with showing the fibers. When I turn this on, rendering
slows down to a crawl, and the results look pretty bad. Basically, the rope
becomes all black. I could be that I am doing something wrong, or that the
version of MegaPov I am using is not compatible with your macros. I still need
to investigate what's wrong. However, there's no rush, cause in my scene there's
no need to show the fibers anyway.

Cheers,

Erwin

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"Eriban" <pov### [at] spamgourmetcom> wrote in message 
news:web.4a411f4899a5bfb681475b100@news.povray.org...
>
> I just thought I'd share my first results of using your rope macro. 
> Attached is
> an image with the result. To create the hanging loops I created a small 
> macro
> of my own. I still need to clean it up a bit and make it a bit more 
> general,
> but then I'll share it.
>
> I still have a problem with showing the fibers. When I turn this on, 
> rendering
> slows down to a crawl, and the results look pretty bad. Basically, the 
> rope
> becomes all black. I could be that I am doing something wrong, or that the
> version of MegaPov I am using is not compatible with your macros. I still 
> need
> to investigate what's wrong. However, there's no rush, cause in my scene 
> there's
> no need to show the fibers anyway.
>

Hi Erwin,

No it's nothing you've done wrong.

As soon as you said that I remembered that I was surprised that I hadn't 
needed to increase the POV-Ray max_trace_level when I developed the outer 
'fibre' layer, because it uses a sort of semi-transparent skin around the 
outside of the rope made out of strings of spheres. This semi-transparent 
layer is why it takes about 10 times as long to render. I developed this 
under 3.7 beta 32 and I had intended to test it on POV-Ray 3.6 before 
posting it, but I forgot.

Now that I tried it on 3.6 it clearly needs the following line adding if 
fibres are used and I would imagine it's the same problem for MegaPOV:
global_settings {max_trace_level 10}

I'm still not really sure why it doesn't need this on the 3.7 beta 32.
I also notice that the lighting levels are a lot darker on 3.6, but I guess 
you've already spotted that and set Rope_Brightness to 2 to compensate, 
because your scene looks bright enough (or maybe MegaPOV is different from 
3.6 on lighting levels).

Best Regards,
Chris B.

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> 
> "Eriban" <pov### [at] spamgourmetcom> wrote in message 
> news:web.4a411f4899a5bfb681475b100@news.povray.org...
>>
>> I just thought I'd share my first results of using your rope macro. 
>> Attached is
>> an image with the result. To create the hanging loops I created a 
>> small macro
>> of my own. I still need to clean it up a bit and make it a bit more 
>> general,
>> but then I'll share it.
>>
>> I still have a problem with showing the fibers. When I turn this on, 
>> rendering
>> slows down to a crawl, and the results look pretty bad. Basically, the 
>> rope
>> becomes all black. I could be that I am doing something wrong, or that 
>> the
>> version of MegaPov I am using is not compatible with your macros. I 
>> still need
>> to investigate what's wrong. However, there's no rush, cause in my 
>> scene there's
>> no need to show the fibers anyway.
>>
> 
> Hi Erwin,
> 
> No it's nothing you've done wrong.
> 
> As soon as you said that I remembered that I was surprised that I hadn't 
> needed to increase the POV-Ray max_trace_level when I developed the 
> outer 'fibre' layer, because it uses a sort of semi-transparent skin 
> around the outside of the rope made out of strings of spheres. This 
> semi-transparent layer is why it takes about 10 times as long to render. 
> I developed this under 3.7 beta 32 and I had intended to test it on 
> POV-Ray 3.6 before posting it, but I forgot.
> 
> Now that I tried it on 3.6 it clearly needs the following line adding if 
> fibres are used and I would imagine it's the same problem for MegaPOV:
> global_settings {max_trace_level 10}
> 
> I'm still not really sure why it doesn't need this on the 3.7 beta 32.
> I also notice that the lighting levels are a lot darker on 3.6, but I 
> guess you've already spotted that and set Rope_Brightness to 2 to 
> compensate, because your scene looks bright enough (or maybe MegaPOV is 
> different from 3.6 on lighting levels).
> 
> Best Regards,
> Chris B.
> 

With version 3.7, when a transparent object don't have reflection nor an 
interior with an ior, passing trough such an object don't count toward 
the max_trace limits. That change happened over 10 versions ago, I 
think. Now, a ray can pass trough over 500 transparent object, giving 
over 1000 surfaces intersections.

Alain

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"Chris B" <nom### [at] nomailcom> wrote:
> Now that I tried it on 3.6 it clearly needs the following line adding if
> fibres are used and I would imagine it's the same problem for MegaPOV:
> global_settings {max_trace_level 10}

Thanks for the reply. Increasing the max_trace_level indeed fixes the problem.
Nevertheless, in the small sample scene I used it the fibers do not enhance the
image as they are too small to show up. The main effect is that they reduce the
overall brightness of the rope a bit. Having said that, it's good to know I can
get the fibres to show up when needed. :-)

A small suggestion. Is it maybe worth adding another quick-rendering option to
the rope macros, alongside the Rope_ShowFibres=0 setting? In some test-renders
you may only want to see the path of the rope, without it having to consist of
multiple strands. For my rope-looping macro I am using a single sphere_sweep
during loop construction (to make sure that the loops do not overlap anywhere).
This sphere_sweep can also be used creating the image. It does not look good of
course (see the attached image), however, it may be handy when contructing the
path for the rope, as it takes less time to generate the image.

In my case (using a simple 1.42 GHz PowerPC MacMini) the rendering and parse
times for my simple "looped rope" image are as follows:
Proper rope, with fibres: Total time 39m30s, of which 1m49s parsing
Proper rope, w/o wibres: Total time 3m44s, of which 1m37s parsing
Simple sphere_sweep: Total time 1m56s, of which 0s parsing

The macro to create the sphere_sweep from the array of points can be very simple
of course. Here's what I have been using:

#macro BuildRope(RopePoints, StartIndex, EndIndex, Radius)
 sphere_sweep {
  cubic_spline
  EndIndex - StartIndex

  #local I = StartIndex;
  #while (I != EndIndex)
   RopePoints[I], Radius
   #local I = I + 1;
  #end
 }
#end

Cheers,
Erwin

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