POV-Ray : Newsgroups : povray.binaries.images : Feature request: Rotation warp Server Time: 19 Aug 2019 15:00:40 GMT
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From: Bald Eagle
Subject: Feature request: Rotation warp
Date: 15 Jul 2019 02:20:01
Message: <web.5d2be21160d36afa4eec112d0@news.povray.org>
So, I was trying to puzzle out how to texture the rotated and twisted pigment
function isosurfaces I've been working on, and it became clear that there's no
way to continually rotate a pigment pattern around an axis as a function of that
abscissa.

To my knowledge there is currently no way to do this to a pigment.

Attached is a simple illustration of a cylinder textured with such a warped
pigment (hexagon).

This was done by taking intersections of the cylinder and thin discs, that were
textured with a progressively rotated version of the pigment and stacked.


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Attachments:
Download 'pigment{} rotation warp.png' (130 KB)

Preview of image 'pigment{} rotation warp.png'
pigment{} rotation warp.png


 

From: Le Forgeron
Subject: Re: Feature request: Rotation warp
Date: 15 Jul 2019 07:02:11
Message: <5d2c24f3@news.povray.org>
Le 15/07/2019 à 04:16, Bald Eagle a écrit :
> 
> So, I was trying to puzzle out how to texture the rotated and twisted pigment
> function isosurfaces I've been working on, and it became clear that there's no
> way to continually rotate a pigment pattern around an axis as a function of that
> abscissa.
> 
> To my knowledge there is currently no way to do this to a pigment.
> 
> Attached is a simple illustration of a cylinder textured with such a warped
> pigment (hexagon).
> 
> This was done by taking intersections of the cylinder and thin discs, that were
> textured with a progressively rotated version of the pigment and stacked.
> 

Looks a lot like attached picture, but for texture instead of shape.

Is there a need for deep control or can a simpler version be enough ?

1. can origin of the axis always be <0,0,0> ?
Or should it be customisable ?

2. can the direction of the axis be specified ?
Or should it always something like +z ?

3. can the handedness of the rotation be always the same ?
Or should it be customisable ?

4. can the distance between two complete rotations be always the same ?
Or should it be customisable ?

5. should the rotation always occurs ?
Or should it occurs only for a bounded range along the axis ?

6. should the rotation be of constant speed along the axis ?
Or should it use something like *dist_exp* from
http://wiki.povray.org/content/Reference:Warp#Mapping_using_warps
with something else than 1 as its value ?


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leforgeronscrew.png


 

From: Bald Eagle
Subject: Re: Feature request: Rotation warp
Date: 15 Jul 2019 10:40:01
Message: <web.5d2c5702746ba36d4eec112d0@news.povray.org>
Le_Forgeron <jgr### [at] freefr> wrote:

> Is there a need for deep control or can a simpler version be enough ?
>
> 1. can origin of the axis always be <0,0,0> ?
> Or should it be customisable ?

I think for most things applying the warp and then a translate would be fine.

> 2. can the direction of the axis be specified ?
> Or should it always something like +z ?

Again, I think for most things applying the warp and then a rotate would be
fine.

> 3. can the handedness of the rotation be always the same ?
> Or should it be customisable ?

Why not just have a signed amount?

> 4. can the distance between two complete rotations be always the same ?
> Or should it be customisable ?

Indeed, I thought of this, and perhaps there's a whole new idea that may dwarf
even this small level of complexity.  *

> 5. should the rotation always occurs ?
> Or should it occurs only for a bounded range along the axis ?

For now, I'd say keep it simple, unless the choice of a bounded is not much more
complicated.

> 6. should the rotation be of constant speed along the axis ?
> Or should it use something like *dist_exp* from
> http://wiki.povray.org/content/Reference:Warp#Mapping_using_warps
> with something else than 1 as its value ?

An excellent question, and one that almost hits on my thoughts on #4 (*)

Perhaps to allow added user-control, with user-defined functions, there can be a
warp_map, such that the affected regions and degree of effect of a warp can be
controlled by a spline.

warp {
     rotate x linear // quadratic cubic bezier
     warp_map {
          [0.00   pi/2] // per POV unit
          [0.50 2*pi]
          [0.75 3*pi/2]
          [0.00   pi/2]
     }
}
This may be way too complicated, as there are a lot of moving parts under the
hood, and I don't know how much this would slow things down if applied.


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From: Bald Eagle
Subject: Re: Feature request: Rotation warp
Date: 15 Jul 2019 20:10:01
Message: <web.5d2cdd5c746ba36d4eec112d0@news.povray.org>
Jerome,

Are you considering experimenting with this warp idea in HgPovRay?

I'd like to install that, but I need some detailed installation instructions -
I've only recently made the full switch-over from M$ to Linux Mint.

Is there a way, at some point, to set that up to be installed with apt-get?
or the Mint "Software Manager"? (mintinstall)

Thanks


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From: Le Forgeron
Subject: Re: Feature request: Rotation warp
Date: 16 Jul 2019 08:34:50
Message: <5d2d8c2a$1@news.povray.org>
Le 15/07/2019 à 22:09, Bald Eagle a écrit :
> Jerome,
> 
> Are you considering experimenting with this warp idea in HgPovRay?

Maybe, but do not hold your breath on it.

> 
> I'd like to install that, but I need some detailed installation instructions -
> I've only recently made the full switch-over from M$ to Linux Mint.

It's the same way as for installing povray from sources (so, not from a
package)
1. get the sources (zip or tar.gz)
2. extract them somewhere
3. run in the extracted directory:  ./unix/prebuild.sh
4. run:  ./configure COMPILED_BY="Bald Eagle"
5. if configure is happy (no missing packages), run: make
6. run: make check
7. either copy unix/povray in /usr/local/bin/hgpovray,
   or run: sudo make install (it overwrites povray !)

you can get sources at https://github.com/LeForgeron/povray/releases

Steps 1 & 2 can be replaced by cloning the git repository, but that's
not for innocent users.

> 
> Is there a way, at some point, to set that up to be installed with apt-get?
> or the Mint "Software Manager"? (mintinstall)
> 

That's a long long long road, I'm not sure to engage.
I would need to set up a ppa:, and add files for the debian generation...
And states if it excludes official povray or can cohabit with it.

> Thanks
>


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From: Le Forgeron
Subject: Re: Feature request: Rotation warp
Date: 17 Jul 2019 15:47:55
Message: <5d2f432b@news.povray.org>
Le 15/07/2019 à 04:16, Bald Eagle a écrit :
> 
> So, I was trying to puzzle out how to texture the rotated and twisted pigment
> function isosurfaces I've been working on, and it became clear that there's no
> way to continually rotate a pigment pattern around an axis as a function of that
> abscissa.
> 
> To my knowledge there is currently no way to do this to a pigment.
> 
> Attached is a simple illustration of a cylinder textured with such a warped
> pigment (hexagon).
> 
> This was done by taking intersections of the cylinder and thin discs, that were
> textured with a progressively rotated version of the pigment and stacked.
> 

Patch done in Hgpovray38
( available at
https://github.com/LeForgeron/povray/releases/tag/v3.8.0.alpha%2BHg.227.Bl%C3%A9

> https://github.com/LeForgeron/povray/releases/tag/v3.8.0.alpha%2BHg.227.Bl%C3%A9


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wr.png


 

From: Bald Eagle
Subject: Re: Feature request: Rotation warp
Date: 17 Jul 2019 18:25:00
Message: <web.5d2f67b9746ba36d4eec112d0@news.povray.org>
Le_Forgeron <jgr### [at] freefr> wrote:

> Patch done in Hgpovray38
> ( available at
> https://github.com/LeForgeron/povray/releases/tag/v3.8.0.alpha%2BHg.227.Bl%C3%A9

LOL.   Somehow I knew you just couldn't resist.  :D

I just got done coding a version in SDL last night, which is part of why I was
trying to get the pigment-mapped pattern in color.

I'll try to get Hg installed soon so I can look it over and play.

Nice work :)


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From: Bald Eagle
Subject: Re: Feature request: Rotation warp
Date: 17 Jul 2019 21:15:00
Message: <web.5d2f8f67746ba36d4eec112d0@news.povray.org>
The twisted pigment makes a fun isosurface, that would fit into some sort of art
gallery scene or corporate sculpture..  ;)


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From: Bald Eagle
Subject: Re: Feature request: Rotation warp
Date: 17 Jul 2019 21:25:00
Message: <web.5d2f9172746ba36d4eec112d0@news.povray.org>
Crackle gives something that would make a fine concretion of seashells or other
conglomerate.


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documentationfigures.png


 

From: Thomas de Groot
Subject: Re: Feature request: Rotation warp
Date: 18 Jul 2019 06:32:16
Message: <5d301270$1@news.povray.org>
On 17-7-2019 23:21, Bald Eagle wrote:
> Crackle gives something that would make a fine concretion of seashells or other
> conglomerate.
> 

Yes! That is a nice one!

-- 
Thomas


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