Got a question for you all:

Does anybody use the advanced features of MegaPov's slope-dependent pattern?
Anything that can be done with the advanced features can be replicated using
a combination of the simple slope pattern, gradient, and color_maps, using
pigment_pattern to combine everything.  Personally, I think the advanced
features are quite confusing and difficult to use.

Therefore, I'm thinking about removing them from future versions of MegaPov
(and probably POV 3.5, also) and keeping only the simple form of slope (
"slope <vector>" ), but I didn't want to do that if enough people thought
they were very useful.

-Nathan

Post a reply to this message

> Does anybody use the advanced features of MegaPov's slope-dependent
pattern?

To be quite frank with you, I haven't really gotten into them because they
are very confusing to me, and I've not had good results with them in my
work. I would really like it if I could use "slope <vector> <vector>", and
have it work as advertised, but I have not had much success with this.

> Therefore, I'm thinking about removing them from future versions of
MegaPov
> (and probably POV 3.5, also) and keeping only the simple form of slope (
> "slope <vector>" ), but I didn't want to do that if enough people thought
> they were very useful.

Go right ahead... but like I said, the second form would be nice if it
worked for me. I had some strange problems with it I'm not sure I can
replicate, but they were there nonetheless.

Post a reply to this message

Hi Nathan

I've tried using the more advanced features and have had mixed success. If
the ideas behind them could be developed they could be very useful. I must
admit I've been deterred from using them by their difficulty. I won't miss
them if they go.

Mick

Post a reply to this message

Nathan Kopp wrote:

> Does anybody use the advanced features of MegaPov's slope-dependent pattern?
> Anything that can be done with the advanced features can be replicated using
> a combination of the simple slope pattern, gradient, and color_maps, using
> pigment_pattern to combine everything.  Personally, I think the advanced
> features are quite confusing and difficult to use.

Same thing here. I also have trouble understanding the advanced features and
wouldn't miss them.
One thing that could be useful though, is to make the slope-dependent pattern
work with turbulence.

G.

--

**********************
http://www.oyonale.com
**********************
Graphic experiments
Pov-ray gallery

Post a reply to this message

Nathan Kopp wrote:
> 
> Got a question for you all:
> 
> Does anybody use the advanced features of MegaPov's slope-dependent pattern?
> Anything that can be done with the advanced features can be replicated using
> a combination of the simple slope pattern, gradient, and color_maps, using
> pigment_pattern to combine everything.  Personally, I think the advanced
> features are quite confusing and difficult to use.
> 
> Therefore, I'm thinking about removing them from future versions of MegaPov
> (and probably POV 3.5, also) and keeping only the simple form of slope (
> "slope <vector>" ), but I didn't want to do that if enough people thought
> they were very useful.
> 

No, please keep them!

As the megapov docu says (and it's quite good to understand in that
section) there are three different types, the first two quite easy to
understand, i use both quite often.  The 'snowman' picture i posted some
time ago to p.b.i. uses 'slope z, z' for the terrain and 'slope z+y' for
the tree.  

The third type is a bit more difficult, i also used it in the past, but
it's not so intuitive to use.  But it also seems to be more difficult to
be replicated with more complicated pigments as you suggested.  

I already thought about writing a slope pattern tutorial in the past.  If
you decide to keep it, i could give it a try, otherwise there is not much
need :-)

Something different: i often like to have a slope pattern not for objects
but for patterns themselves or pigments, like:

pigment {
  slope y {
    [pattern]
  }
  color_map { ... }
}

This would be quite useful for isosurface functions for example.  I have
no idea right now if that's easy to implement, just an idea.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

Post a reply to this message

"Nathan Kopp" <Nat### [at] Koppcom> wrote in message
news:3a5525bc@news.povray.org...
> Got a question for you all:
>

Well, I've never used type 3, but I will cry if you remove type 2.

Post a reply to this message

I have been playing with the slope dependent texturing quite a bit lately -
I have found that it is really useful (at least for my stuff anyway...).
Put my vote for keeping types 1 and 2.  I haven't gotten the hang of 3
(yet).

--  the autowitch

Post a reply to this message

In article <3A558D6B.61C493BF@gmx.de>, Christoph Hormann 
<chr### [at] gmxde> wrote:

> Something different: i often like to have a slope pattern not for objects
> but for patterns themselves or pigments, like:
...snip...
> This would be quite useful for isosurface functions for example.  I have
> no idea right now if that's easy to implement, just an idea.

Are you thinking of something for the gradient of a pattern? A pattern 
that would return higher values in areas that change rapidly, but 
approach 0 in "flat" areas? The displace warp can do something similar, 
the code could probably be modified to do this pattern(maybe a more 
general pattern that calculates the "amount of warping" for any warp). 
Actually, you could probably do it with an isosurface function...I don't 
know how useful it would be in isosurfaces, though.

-- 
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

Chris Huff wrote:
> 
> Are you thinking of something for the gradient of a pattern? A pattern
> that would return higher values in areas that change rapidly, but
> approach 0 in "flat" areas? 

That's exactly what i meant.

> The displace warp can do something similar,
> the code could probably be modified to do this pattern(maybe a more
> general pattern that calculates the "amount of warping" for any warp).

I think that would suffice, since a warp does not only specify the amount
but also the direction, this could be even more universal.

> Actually, you could probably do it with an isosurface function...I don't
> know how useful it would be in isosurfaces, though.
> 

Not sure whow you mean that, the purpose i was thinking of was for example
controlling the fine structure of an isosurface landscape depending on the
slope of it's large scale shape.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

Post a reply to this message

In article <3A565458.62638751@gmx.de>, Christoph Hormann 
<chr### [at] gmxde> wrote:

> I think that would suffice, since a warp does not only specify the amount
> but also the direction, this could be even more universal.

Well, the warping vector can't be used directly, since patterns are 
float values only...I was thinking of using the length of the warp 
vector.


> Not sure whow you mean that, the purpose i was thinking of was for example
> controlling the fine structure of an isosurface landscape depending on the
> slope of it's large scale shape.

Ah, I see...well, declare the large scale function, and use something 
like:
#declare P = 0.01;// sampling distance
#declare Fn = function {...}

#declare MaxSlopeFn =
function {
    max(max(
        (abs(Fn(x+P, y, z)-Fn(x-P, y, z))),
         abs(Fn(x, y+P, z)-Fn(x, y-P, z)))),
         abs(Fn(x, y, z+P)-Fn(x, y, z-P)))
    )/(2*P)
}

-- 
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