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29 Mar 2024 06:45:45 EDT (-0400)
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From: Le Forgeron
Subject: Re: Tetrahedral planetoid
Date: 12 Jun 2019 13:39:28
Message: <5d0138d0$1@news.povray.org>
Le 12/06/2019 à 02:14, Bald Eagle a écrit :
> How about some cloud cover?
> 
> I ran across
> http://abx.art.pl/pov/patches/f_triangle.php
> 
> and that might be adaptable to a tetrahedral shape to make cloud media...
> 

the code computes the distance of the point to the nearest edge defined
by the 3 points (on an oriented triangle, projecting on the plane of the
triangle first).

For tetrahedral adaptation, you would need to compute the distance of
the point to the nearest plane defined by each set of 3 points.
(actually, oriented planes, one side of each plane is to be ignored)

The performance problem here, due to the lack of dedicated data
structure, is already that each evaluation need to recompute again and
again the same pieces of data that are not dependant on the evaluated
point P(x,y,z)

It's going to be worse with distance to planes if the input is user
friednly (such as 4 points) instead of précomputed 4 planes (4 normals &
4 offsets).

And do not forget a last value, the thickness (actually offset for the
result).

But as provided, the process is still doable in code of 3.8 (just adapt
to the new structures/filenames).

Maybe defining pattern/pigment is easier (and faster for the VM), via
function{ pigment/pattern { ... }}, as a pigment can have precomputed
data in its own storage. (so input can be 4 points & thickness, and the
pigment precomputes its data).

It would be a pigment like boxed, but with an explicit tetrahedron and a
thickness. Due to thickness, a fixed tetrahedron and a transform is not
suitable.


Looking at the code, parser/parser_materials.cpp, it seems there is a
bit of todo for square & triangular , it should be similar to checker &
hexagon but so far they are rejected.


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From: Bill Pragnell
Subject: Re: Tetrahedral planetoid
Date: 12 Jun 2019 14:00:06
Message: <web.5d013cec7edc39d71b6c6b3a0@news.povray.org>
Le_Forgeron <jgr### [at] freefr> wrote:
[snip]

I feel that this world is a sphere, with only the piled-up city forming a
tetrahedral shape. I think any cloud cover would be spherical... although I'm
not convinced I need any, it would just obscure the detail of the planetoid.
Some very light wispy cloud perhaps.

Interesting idea though!

Bill


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From: Bill Pragnell
Subject: Re: Tetrahedral planetoid
Date: 12 Jun 2019 14:00:10
Message: <web.5d013d1c7edc39d71b6c6b3a0@news.povray.org>
Thomas de Groot <tho### [at] degrootorg> wrote:
> Aaah! A return to the tetrahedral universe!

I have a platonic relationship with it ;)


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From: Mike Horvath
Subject: Re: Tetrahedral planetoid
Date: 12 Jun 2019 22:47:54
Message: <5d01b95a$1@news.povray.org>
On 6/12/2019 1:05 PM, Bill Pragnell wrote:
> "Bald Eagle" <cre### [at] netscapenet> wrote:
>> Also, a night scene would be pretty cool.
> 
> Aha, yes could be good. I'd need many lights though, which could be problematic.
> Moonlight perhaps.
> 

I think you can make a light source only affect certain objects using 
"light_group", thus reducing rendering time.


Michael


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From: Thomas de Groot
Subject: Re: Tetrahedral planetoid
Date: 13 Jun 2019 02:57:57
Message: <5d01f3f5$1@news.povray.org>
On 12-6-2019 19:05, Bill Pragnell wrote:
> "Bald Eagle" <cre### [at] netscapenet> wrote:
>> Also, a night scene would be pretty cool.
> 
> Aha, yes could be good. I'd need many lights though, which could be problematic.
> Moonlight perhaps.
> 

Instead of lights, you can use finish {emission 1} for the window panes.

-- 
Thomas


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From: Thomas de Groot
Subject: Re: Tetrahedral planetoid
Date: 13 Jun 2019 02:58:36
Message: <5d01f41c@news.povray.org>
On 12-6-2019 19:57, Bill Pragnell wrote:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> Aaah! A return to the tetrahedral universe!
> 
> I have a platonic relationship with it ;)
> 

Of course! :-)

-- 
Thomas


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From: Bill Pragnell
Subject: Re: Tetrahedral planetoid
Date: 13 Jun 2019 16:20:00
Message: <web.5d02af8b7edc39d71b6c6b3a0@news.povray.org>
Thomas de Groot <tho### [at] degrootorg> wrote:
> On 12-6-2019 19:05, Bill Pragnell wrote:
> > "Bald Eagle" <cre### [at] netscapenet> wrote:
> >> Also, a night scene would be pretty cool.
> >
> > Aha, yes could be good. I'd need many lights though, which could be problematic.
> > Moonlight perhaps.
> >
>
> Instead of lights, you can use finish {emission 1} for the window panes.

Yes, and since I've been using UberPOV of late, this is probably the best
solution.


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From: Bill Pragnell
Subject: Re: Tetrahedral planetoid
Date: 13 Jun 2019 16:25:01
Message: <web.5d02b0277edc39d71b6c6b3a0@news.povray.org>
Mike Horvath <mik### [at] gmailcom> wrote:
> On 6/12/2019 1:05 PM, Bill Pragnell wrote:
> > "Bald Eagle" <cre### [at] netscapenet> wrote:
> >> Also, a night scene would be pretty cool.
> >
> > Aha, yes could be good. I'd need many lights though, which could be problematic.
> > Moonlight perhaps.
> >
>
> I think you can make a light source only affect certain objects using
> "light_group", thus reducing rendering time.

Yes, that's the problem I had in mind! Will be quite fiddly to segregate this
scene given how it's been assembled. I think emissive windows / lightblobs with
UberPOV's count cranked up is the way I'll be heading...


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From: Alain
Subject: Re: Tetrahedral planetoid
Date: 14 Jun 2019 08:58:28
Message: <5d0399f4$1@news.povray.org>
Le 19-06-13 à 16:18, Bill Pragnell a écrit :
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> On 12-6-2019 19:05, Bill Pragnell wrote:
>>> "Bald Eagle" <cre### [at] netscapenet> wrote:
>>>> Also, a night scene would be pretty cool.
>>>
>>> Aha, yes could be good. I'd need many lights though, which could be problematic.
>>> Moonlight perhaps.
>>>
>>
>> Instead of lights, you can use finish {emission 1} for the window panes.
> 
> Yes, and since I've been using UberPOV of late, this is probably the best
> solution.
> 

Using finish{emission 1} is not limited to UberPOV. It works very well 
in version 3.7+


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From: Bill Pragnell
Subject: Re: Tetrahedral planetoid
Date: 14 Jun 2019 10:00:01
Message: <web.5d03a77b7edc39d71b6c6b3a0@news.povray.org>
Alain <kua### [at] videotronca> wrote:
> Le 19-06-13 à 16:18, Bill Pragnell a écrit :
> > Thomas de Groot <tho### [at] degrootorg> wrote:
> >> On 12-6-2019 19:05, Bill Pragnell wrote:
> >>> "Bald Eagle" <cre### [at] netscapenet> wrote:
> >>>> Also, a night scene would be pretty cool.
> >>>
> >>> Aha, yes could be good. I'd need many lights though, which could be problematic.
> >>> Moonlight perhaps.
> >>>
> >>
> >> Instead of lights, you can use finish {emission 1} for the window panes.
> >
> > Yes, and since I've been using UberPOV of late, this is probably the best
> > solution.
> >
>
> Using finish{emission 1} is not limited to UberPOV. It works very well
> in version 3.7+

Yes, but I find decent radiosity results difficult to achieve in base POV-Ray
without very slow renders. I think the slight graininess of Uber is a good
trade-off for speed and zero artefacts!


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