Back to modelling on the ship. I was referencing some photos of actual ships
rigging when I noticed that rope comes in many shades depending on the wear
and age of the rope (I am guessing). SO I thought I would revisit the macro
that piles loops of rope on the belaying pins and have it vary the shade of
the rope randomly withing a given range. That seems to work out pretty
well, however...I don't like the fact that the texture does not follow the
sphere sweep, but is applied to the entire sphere sweep after the fact. I
can not find a fix for this in the documents. Does anybody know if there is
a fix?

Tim

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Attachments:
Download 'belayingtest.jpg' (84 KB)

Preview of image 'belayingtest.jpg'

Tim McMurdo wrote:

> Back to modelling on the ship. I was referencing some photos of actual
> ships rigging when I noticed that rope comes in many shades depending on
> the wear and age of the rope (I am guessing). SO I thought I would revisit
> the macro that piles loops of rope on the belaying pins and have it vary
> the shade of the rope randomly withing a given range. That seems to work
> out pretty well, however...I don't like the fact that the texture does not
> follow the sphere sweep, but is applied to the entire sphere sweep after
> the fact. I can not find a fix for this in the documents. Does anybody
> know if there is a fix?
> 
> Tim

Well, not a fix, an alternative, but it's *seriously* slower:

Turn the points of your sphere sweep into a spline function.
Use the spline function to place spheres close together in a blob.
Keep track of the distance along the rope by adding up the
        distances between the spheres.
Use the distance along the rope to translate a texture from
        where the rope would be if it were streight to where
        it is when it is curled up, and rotate the texture also
        to point along the direction of the spline.
Texture each sphere of the blob separately in this way. If they
        are close enough together they will blend.
You can see the effect in that pic I just posted, the bark of
the nearby tree.

I can share the code if this doesn't sound like complete overkill! :-)

-- 
Bill Hails
http://thyme.homelinux.net/

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You could replace the sphere sweep with a macro-generated mesh "tube," and
then UV-map it. (This may also render faster.)

 - Slime
 [ http://www.slimeland.com/ ]

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Wasn't it Tim McMurdo who wrote:
>Back to modelling on the ship. I was referencing some photos of actual ships
>rigging when I noticed that rope comes in many shades depending on the wear
>and age of the rope (I am guessing). SO I thought I would revisit the macro
>that piles loops of rope on the belaying pins and have it vary the shade of
>the rope randomly withing a given range. That seems to work out pretty
>well, however...I don't like the fact that the texture does not follow the
>sphere sweep, but is applied to the entire sphere sweep after the fact. I
>can not find a fix for this in the documents. Does anybody know if there is
>a fix?

Sphere sweeps don't currently support uv_mapping. You could replace the
sphere sweep with a mesh, which can be uv_mapped. The SweepSpline macro,
which can currently be found at the bottom of this page
 <http://www.econym.demon.co.uk/isotut/more.htm>
will do the job. Use your existing spline as the "U" Spline, a closed
circular spline as the "V" Spline cross section, and a linear spline of
constant width as the "W" Spline, since the width of the rope doesn't
vary.

-- 
Mike Williams
Gentleman of Leisure

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"Tim McMurdo" <jod### [at] wohrrcom> wrote:
> Back to modelling on the ship. I was referencing some photos of actual ships
> rigging when I noticed that rope comes in many shades depending on the wear
> and age of the rope (I am guessing). SO I thought I would revisit the macro
> that piles loops of rope on the belaying pins and have it vary the shade of
> the rope randomly withing a given range. That seems to work out pretty
> well, however...I don't like the fact that the texture does not follow the
> sphere sweep, but is applied to the entire sphere sweep after the fact. I
> can not find a fix for this in the documents. Does anybody know if there is
> a fix?
>
> Tim

 The rigging on sailing ships comes in two types: Standing rigging and
running rigging. Standing rigging is used for shrouds, stays etc. Running
rigging is used for sheets, sail trimming etc. The standing rigging is
tared for weather protection, while the running rigging is not. As a result,
standing rigging is almist black, while running
rigging will vary in color as it ages, from light tan to grey. Also, there
are two types of rope: Rope
and cable. Rope has a clock-wise or right-hand twist, while cable has a
counterclock-wise or lefthand twist.

As a side note, your model should have some shear to it, i.e. a upward bend
to the side of the ship. The shear follows a circle of very large radius.
This radius increasted over time. During the Elisabethan era it was rather
small. By the end of the Age-of-Sail it had increased to the point that the
shear was almost gone. A good referance is Dean's Doctrine of Naval
Architecture, 1670. It is available in re-print.

Ken Matassa

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Lots of great suggestions. I will try each of them and see which fits best.
Thank you for your help.

Tim

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Bill Hails <bil### [at] europeyahoo-inccom> wrote:
> Well, not a fix, an alternative, but it's *seriously* slower:
>
> Turn the points of your sphere sweep into a spline function.
> Use the spline function to place spheres close together in a blob.
> Keep track of the distance along the rope by adding up the
>         distances between the spheres.
> Use the distance along the rope to translate a texture from
>         where the rope would be if it were streight to where
>         it is when it is curled up, and rotate the texture also
>         to point along the direction of the spline.
> Texture each sphere of the blob separately in this way. If they
>         are close enough together they will blend.
> You can see the effect in that pic I just posted, the bark of
> the nearby tree.
>
> I can share the code if this doesn't sound like complete overkill! :-)

I think it's not neccessary to actually use blobs. I did something very
similar (see attachment) using just spheres: If you use enough of them the
object will look smooth but it seems to be quite fast.

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Attachments:
Download 'spline.jpg' (10 KB)

Preview of image 'spline.jpg'

Carl Friedrich Bolz wrote:

> I think it's not neccessary to actually use blobs. I did something very
> similar (see attachment) using just spheres: If you use enough of them the
> object will look smooth but it seems to be quite fast.

yes, of course. I was wrong to suggest blobs, my particular
application needed blobs, but spheres should be a lot faster
if you can get away with it.

-- 
Bill Hails
http://thyme.homelinux.net/

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