Hello all. I'm in the process of making a website.

I have one gallery and a complete tutorial ready. The tutorial is for
learning how to make isosurfaces. I encourage all who want to learn
about isosurfaces to visit it. Enjoy!

The url is:

http://members.aol.com/stbenge/

--
Samuel Benge

STB### [at] aolcom

"While you were sleeping
he went on keeping the final line in his mind."
 -Tortoise and the Hare, The Moody Blues

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Oh, could I get some feedback about the tutorial? Either a post or e-mail
is fine. I just need to know if it is worth putting up more isosurface
tutorials. Thanks.

"SamuelT." wrote:

> Hello all. I'm in the process of making a website.
>
> I have one gallery and a complete tutorial ready. The tutorial is for
> learning how to make isosurfaces. I encourage all who want to learn
> about isosurfaces to visit it. Enjoy!
>
> The url is:
>
> http://members.aol.com/stbenge/
>
> --
> Samuel Benge
>
> STB### [at] aolcom
>
> "While you were sleeping
> he went on keeping the final line in his mind."
>  -Tortoise and the Hare, The Moody Blues

--
Samuel Benge

STB### [at] aolcom

"While you were sleeping
he went on keeping the final line in his mind."
 -Tortoise and the Hare, The Moody Blues

Post a reply to this message

> Oh, could I get some feedback about the tutorial? Either a post or e-mail
> is fine. I just need to know if it is worth putting up more isosurface
> tutorials. Thanks.

Yes more more, we want more!  The images alone are worth the endevour, IMO.

-Mike

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Mike wrote:

> Yes more more, we want more!

Unquestionably !

-- 
Ken Tyler

See my 700+ Povray and 3D Rendering and Raytracing Links at:
http://home.pacbell.net/tylereng/index.html

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Well I found it helpful and await more!

    Um... but does anyone else have more? I found the doc's of the
superpatch to be rather sparse.



SamuelT. <STB### [at] aolcom> wrote in message
news:37C0A403.D4339684@aol.com...
> Hello all. I'm in the process of making a website.
>
> I have one gallery and a complete tutorial ready. The tutorial is for
> learning how to make isosurfaces. I encourage all who want to learn
> about isosurfaces to visit it. Enjoy!
>
> The url is:
>
> http://members.aol.com/stbenge/
>
> --
> Samuel Benge
>
> STB### [at] aolcom
>
> "While you were sleeping
> he went on keeping the final line in his mind."
>  -Tortoise and the Hare, The Moody Blues
>
>

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I agree! Your examples and tutorial finally prompted me to download the
Superpatch. I've been playing around with it and it's quite interesting,
but also very frustrating. I kind of feel like a blindfolded gunman who
has been spun around and told to shoot at the target. I don't have
enough confidence in my math abilities at the moment to be able to
predict the results of my experiments once they go beyond the simple
sphere/cylinder/superellipsoid.

Any suggestions, tutorials, sample forumlae, etc.. would be welcome.
Most of my results, though interesting, seem to end up being infinite
(or seem so) in size. :{P

I "did" get an interesting effect with this:

difference {
 isosurface{
  function{ abs(cos(x)+cos(z)+sin(y))}
  threshold 0.25
  sign 1
  bounded_by{sphere {0,80}}
  hollow
 }
 torus {85,30 hollow}
 pigment {rgb<(63/255),(38/255),(7/255)>}
 finish {specular 0.76 roughness 0.075 ambient 0.54 diffuse 0.62}
}

I have a question on this as well. I'll post an image in
binaries.images. I tried plunking a light inside this object. Light
pours out quite nicely onto the plane that intersects the object, but
does not shine within (even with a Hollow added to the isosurface and
torus). It's almost as if the "holes" in the object let light pass
through, but not impact upon the interior of the object. Am I wrong in
this?

David

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Bill DeWitt wrote:

> Well I found it helpful and await more!

I'm glad to hear it.


>     Um... but does anyone else have more? I found the doc's of the
> superpatch to be rather sparse.

What do you need to know?


STB### [at] aolcom

"While you were sleeping
he went on keeping the final line in his mind."
 -Tortoise and the Hare, The Moody Blues

Post a reply to this message

David Heys wrote:

> I agree! Your examples and tutorial finally prompted me to download the
> Superpatch. I've been playing around with it and it's quite interesting,
> but also very frustrating. I kind of feel like a blindfolded gunman who
> has been spun around and told to shoot at the target. I don't have
> enough confidence in my math abilities at the moment to be able to
> predict the results of my experiments once they go beyond the simple
> sphere/cylinder/superellipsoid.

My math abilites aren't that great either. Most of what I know about making
functions I learned from hours of experimentation; trying out strange things
like abs and sqr, which I didn't know anything about beforehand. Persistance
will help you in your endeavor.


> Any suggestions, tutorials, sample forumlae, etc.. would be welcome.
> Most of my results, though interesting, seem to end up being infinite
> (or seem so) in size. :{P

<snip code>

I hope to be adding a couple more tutorials soon. I think such things as
noise3d and the pigment functions are very neat and have many applications.


> I have a question on this as well. I'll post an image in
> binaries.images. I tried plunking a light inside this object. Light
> pours out quite nicely onto the plane that intersects the object, but
> does not shine within (even with a Hollow added to the isosurface and
> torus). It's almost as if the "holes" in the object let light pass
> through, but not impact upon the interior of the object. Am I wrong in
> this?
>
> David

After reading your post, I tried some experiements using your code. I tried
all of the things that I could think of that might solve the problem, but
the problems remain anyway. I even tried making the torus you used have
no_shadow. I'm starting to think that it might be a bug. Strangely enough, I
have never used csg operations with isosurfaces.

Here, this will perform an intersection inside your isosurface function:

function{ (your function)&(function to be intersected with) }

Both functions must be within parentheses as shown. The & is like intersect
for functions. Here is an example of this feature which makes a sphere cut
in half by a y plane:

function{ (x^2+y^2+z^2)&(y+1) }

By the way, I have run into that shape you posted. It is an infinite shape,
to be sure. I like the way you use your rgb colors, too! It's a good way to
convert rgb colors from a paint application to pov.


--
Samuel Benge

STB### [at] aolcom

"While you were sleeping
he went on keeping the final line in his mind."
 -Tortoise and the Hare, The Moody Blues

Post a reply to this message

SamuelT. wrote:

> My math abilites aren't that great either. Most of what I know about making
> functions I learned from hours of experimentation; trying out strange things
> like abs and sqr, which I didn't know anything about beforehand. Persistance
> will help you in your endeavor.
>

<smile> I planned to do that regardless.

> I hope to be adding a couple more tutorials soon. I think such things as
> noise3d and the pigment functions are very neat and have many applications.
>

I haven't quite gotten there yet. :{)

> After reading your post, I tried some experiements using your code. I tried
> all of the things that I could think of that might solve the problem, but
> the problems remain anyway. I even tried making the torus you used have
> no_shadow. I'm starting to think that it might be a bug. Strangely enough, I
> have never used csg operations with isosurfaces.
>
> Here, this will perform an intersection inside your isosurface function:
>
> function{ (your function)&(function to be intersected with) }
>
> Both functions must be within parentheses as shown. The & is like intersect
> for functions. Here is an example of this feature which makes a sphere cut
> in half by a y plane:
>
> function{ (x^2+y^2+z^2)&(y+1) }
>
> By the way, I have run into that shape you posted. It is an infinite shape,
> to be sure. I like the way you use your rgb colors, too! It's a good way to
> convert rgb colors from a paint application to pov.
>

Is it possible you could post the isosurface function for a torus so I could try
it with the intersection method you've mentioned? As an aside, how do you scale
one of these things? Every attempt I've made has resulted in very odd reactions.
Maybe there's a specific place I should put the scale command, or should I just:

function {((my function)*Scale_Factor)}
or
function {((my function)/Scale_Factor)}

I use the #/255 for my rgb quite often as pretty much half of what I do with POV
these days is destined to be used on a website somewhere. Having to use parts of
POV scenes and other items in Photoshop, I find it convenient to use the #/255
method.

David

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I started to read this tutorial and found the first error in less than
one minute... :)
  I quote:

> bounded_by - This gives the isosurface a limit. For instance, if you make an
> isosurface sphere that is larger than 1 at its radius, and you put 

> bounded_by{ box{ <-1,-1,-1>,<1,1,1> } } 

> in the isosurface statement, what do you think will happen? The box will
> cut into the sphere, giving you an intersected box and sphere, the sphere
> having 6 flat sides. 

  I don't know if this works differently with isosurfaces since I have never
used the superpatch, but if bounded_by works as usual, that's not true.
  I think that you are confusing bounded_by and clipped_by together.
clipped_by cuts the object like an intersection does (except that it doesn't
add a new surface to the cut part). bounded_by just bounds the object. The
result is that the object becomes clipped by the projection of the bounding
object on screen. This is completely different from being clipped in
3D-space.
  If you want your bounding object to also clip the object, you have to do:

clipped_by { box { -1,1 } }
bounded_by { clipped_by }

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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