POV-Ray : Newsgroups : povray.binaries.images : NURBS Server Time
1 Jun 2024 15:34:03 EDT (-0400)
  NURBS (Message 26 to 35 of 55)  
<<< Previous 10 Messages Goto Latest 10 Messages Next 10 Messages >>>
From: LanuHum
Subject: Re: NURBS
Date: 29 Jul 2016 12:15:01
Message: <web.579b801c6d1ce2047a3e03fe0@news.povray.org>
"LanuHum" <Lan### [at] yandexru> wrote:
> "LanuHum" <Lan### [at] yandexru> wrote:
> > Does not work. Empty image. :(
>
> Sorry!I do not put a fourth option 'W'!
> It works, but the model is different from the render result.

Compare renderings:


Post a reply to this message


Attachments:
Download 'nurbs_diff.jpg' (99 KB)

Preview of image 'nurbs_diff.jpg'
nurbs_diff.jpg


 

From: Le Forgeron
Subject: Re: NURBS
Date: 29 Jul 2016 12:22:22
Message: <579b82be$1@news.povray.org>
Le 29/07/2016 à 18:11, LanuHum a écrit :
> "LanuHum" <Lan### [at] yandexru> wrote:
>> "LanuHum" <Lan### [at] yandexru> wrote:
>>> Does not work. Empty image. :(
>>
>> Sorry!I do not put a fourth option 'W'!
>> It works, but the model is different from the render result.
> 
> Compare renderings:
> 
> 

Can you provide the set of control points ?


Post a reply to this message

From: LanuHum
Subject: Re: NURBS
Date: 29 Jul 2016 12:40:00
Message: <web.579b86376d1ce2047a3e03fe0@news.povray.org>
Le_Forgeron <jgr### [at] freefr> wrote:

> Can you provide the set of control points ?

Yes!
#version 3.7;

#include "functions.inc"
global_settings {
    assumed_gamma 1.000000
    max_trace_level 3
    charset utf8
}
sky_sphere {
    pigment {rgb<0.051, 0.051, 0.051>}
}

#declare Default_texture = texture{pigment {rgb 0.8}}

#declare Material = texture{
    pigment{color srgbft <0.8000,0.0946,0.0441,0.0000,0.0000>}
    finish{
        diffuse 0.8000
        brilliance 1.8000
          }
}
#declare data_SurfPatch_ob =
nurbs {7,7 accuracy 0.01
 <-4.1894,-5.4790,0.0000,1.0000> <-4.1894,-4.3181,2.0249,1.0000>
<-4.1894,-2.8825,0.0000,1.0000> <-4.1894,-1.5000,0.0000,1.0000>
<-4.1894,-0.5000,0.0000,1.0000> <-4.1894,0.5000,0.0000,1.0000>
<-4.1894,1.5000,0.0000,1.0000> <-2.6808,-4.8585,0.6794,1.0000>
 <-2.6808,-4.3181,2.0249,1.0000> <-2.6808,-2.8825,0.0000,1.0000>
<-2.6808,-1.5000,3.2519,1.0000> <-2.6808,-0.5000,0.0000,1.0000>
<-2.6808,0.5000,0.0000,1.0000> <-2.6808,1.5000,3.2103,1.0000>
<-1.5000,-5.4790,0.0000,1.0000>
 <-1.5000,-4.3181,2.0249,1.0000> <-1.5000,-2.8825,0.0000,1.0000>
<-1.5000,-1.5000,0.0000,1.0000> <-1.5000,-0.5000,1.2319,1.0000>
<-1.5000,0.5000,0.0000,1.0000> <-1.5000,1.5000,0.0000,1.0000>
<-0.5000,-5.4790,0.0000,1.0000>
 <-0.5000,-4.3181,0.0000,1.0000> <-0.5000,-2.8825,1.7624,1.0000>
<-0.5000,-1.5000,0.0000,1.0000> <-0.5000,-0.5000,1.0000,1.0000>
<-0.5000,0.5000,1.0000,1.0000> <-0.5000,1.5000,0.0000,1.0000>
<0.5000,-5.4790,0.0000,1.0000>
 <0.5000,-4.3181,0.0000,1.0000> <0.5000,-2.8825,0.0000,1.0000>
<0.5000,-1.5000,1.1552,1.0000> <0.5000,-0.5000,1.0000,1.0000>
<0.5000,0.5000,1.0000,1.0000> <0.5000,1.5000,0.0000,1.0000>
<1.5000,-5.4790,1.9780,1.0000>
 <1.5000,-4.3181,0.0000,1.0000> <1.5000,-2.8825,1.7335,1.0000>
<1.5000,-1.5000,0.0000,1.0000> <1.5000,-0.5000,0.0000,1.0000>
<1.5000,0.5000,0.0000,1.0000> <1.5000,1.5000,1.5217,1.0000>
<2.9668,-5.4790,-0.2469,1.0000>
 <2.9668,-4.3181,0.0000,1.0000> <2.9668,-2.8825,0.0000,1.0000>
<2.9668,-1.5000,0.0000,1.0000> <2.9668,-0.5000,-2.9599,1.0000>
<2.9668,0.5000,0.0000,1.0000> <2.9668,1.5000,0.0000,1.0000>
texture{Material}
}
object {data_SurfPatch_ob
    matrix <1.000000, 0.000000, 0.000000,  0.000000, -0.000000, -1.000000,
0.000000, 1.000000, -0.000000,  0.000000, -0.000000, -3.620508>
}

light_source {
    <4.08,5.9,-1.01>
    color rgb<1, 1, 1>
    fade_distance 29.9999828339
    fade_power 1
}
camera {
    perspective
    location  <0,0,0>
    look_at  <0,0,-1>
    right <-1.7777777777777777, 0, 0>
    up <0, 1, 0>
    angle  49.134343
    rotate  <-26.440706, 46.691945, -0.000003>
    translate <7.481132, 5.343666, 6.507640>
}

But, I have found the cause elsewhere.
Blender has a nurbs option warrant.
Increasing the value closer look, but the maximum value of 6 does not give an
exact match. 7 or 8 is required, but the maximum value of 6. :(


Post a reply to this message


Attachments:
Download 'nurbs_order.jpg' (36 KB)

Preview of image 'nurbs_order.jpg'
nurbs_order.jpg


 

From: Le Forgeron
Subject: Re: NURBS
Date: 29 Jul 2016 12:53:40
Message: <579b8a14$1@news.povray.org>
Le 29/07/2016 à 18:37, LanuHum a écrit :
> But, I have found the cause elsewhere.
> Blender has a nurbs option warrant.
> Increasing the value closer look, but the maximum value of 6 does not give an
> exact match. 7 or 8 is required, but the maximum value of 6. :(
> 

Ok, so all is fine, and no need to investigate, right ?


Post a reply to this message

From: LanuHum
Subject: Re: NURBS
Date: 29 Jul 2016 14:05:00
Message: <web.579b99fd6d1ce2047a3e03fe0@news.povray.org>
Le_Forgeron <jgr### [at] freefr> wrote:
> Le 29/07/2016 à 18:37, LanuHum a écrit :
> > But, I have found the cause elsewhere.
> > Blender has a nurbs option warrant.
> > Increasing the value closer look, but the maximum value of 6 does not give an
> > exact match. 7 or 8 is required, but the maximum value of 6. :(
> >
>
> Ok, so all is fine, and no need to investigate, right ?

Your wish. But your nurbs difficult terrain models. Blender nurbs - good terrain
model. Your model also need a order_u and order_v. :)
I added nurbs export code to Povray-HG. Mr can move it to the official version
of the exporter, if it becomes available in the Povray-3.7.1.


Post a reply to this message

From: Le Forgeron
Subject: Re: NURBS
Date: 30 Jul 2016 03:09:13
Message: <579c5299$1@news.povray.org>
Le 29/07/2016 à 20:01, LanuHum a écrit :
> Le_Forgeron <jgr### [at] freefr> wrote:
>> Le 29/07/2016 à 18:37, LanuHum a écrit :
>>> But, I have found the cause elsewhere.
>>> Blender has a nurbs option warrant.
>>> Increasing the value closer look, but the maximum value of 6 does not give an
>>> exact match. 7 or 8 is required, but the maximum value of 6. :(
>>>
>>
>> Ok, so all is fine, and no need to investigate, right ?
> 
> Your wish. But your nurbs difficult terrain models. Blender nurbs - good terrain
> model. Your model also need a order_u and order_v. :)
> I added nurbs export code to Povray-HG. Mr can move it to the official version
> of the exporter, if it becomes available in the Povray-3.7.1.


That request opens more things than expected: unclamped vs clamped ( closed vs opened
curve) and combination of different options by direction(u,v)

I would need a few more round tuits and my stock is low.


Post a reply to this message

From: LanuHum
Subject: Re: NURBS
Date: 30 Jul 2016 07:15:00
Message: <web.579c8bd46d1ce2047a3e03fe0@news.povray.org>
Le_Forgeron <jgr### [at] freefr> wrote:

> I would need a few more round tuits and my stock is low.

:))))))
And who is now easy to live?


Post a reply to this message

From: Le Forgeron
Subject: Re: NURBS
Date: 31 Jul 2016 03:17:46
Message: <579da61a$1@news.povray.org>
Le 30/07/2016 à 13:13, LanuHum a écrit :
> Le_Forgeron <jgr### [at] freefr> wrote:
> 
>> I would need a few more round tuits and my stock is low.
> 
> :))))))
> And who is now easy to live?
> 

For the technically inclined, it would involves replacing the de Casteljau's algorithm
with de Boor's algorithm.

And it breaks a lot of things, including the weights used at each iteration of the leg
reduction.


Post a reply to this message

From: Christian Froeschlin
Subject: Re: NURBS
Date: 31 Jul 2016 19:51:28
Message: <579e8f00$1@news.povray.org>
On 24.07.2016 4:13, clipka wrote:

> What's been bothering me about POV-Ray's Bezier patches is that we don't
> have some kind of bezier mesh to support non-union CSG. Do you think you
> can throw together a nurbs mesh primitive?

 From what I remember of B-splines I think a B-spline patch
of degree d is essentially the same thing as a mesh of bezier
patches of degree d (with the smoothest possible transition
where the bezier control blocks are joined).

So I'm not sure an extra mesh object is needed since you can simply
increase the number of control points. Or maybe I misunderstood?

Now that I think about it I didn't see any mention of degree,
so maybe the new NURBS implementation is for degree 2 only?


Post a reply to this message

From: Mr
Subject: Re: NURBS
Date: 1 Aug 2016 05:10:01
Message: <web.579f11726d1ce20416086ed00@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
> Am 24.07.2016 um 11:31 schrieb LanuHum:
> > clipka <ano### [at] anonymousorg> wrote:
> >
> >> @LanuHum:
> >> Does Blender provide full support for NURBS? If so, then this looks like
> >> an urgent job for you!
> >
> > It is very good that made Le Forgeron!
> > Le Forgeron, thank you!
> > Hair in Blender - NURBS.
>
> Are you sure Blender hair uses NURBS /patches/ (which is what LeForgeron
> has implemented) and not NURBS /curves/?


Indeed Blender hair does not use NURBS. it's some kind of pixel/screen space
geometry, derived from particles historically, I believe. It used to drop
calculations for any hair that looked smaller than one pixel fraction on screen,
according to antialiasing settings.

At one point, Blender NURBS were implemented from an external open source
library : libNurbana
https://sourceforge.net/projects/nurbana/?source=directory
Don't know if it's still the case.

I think what Lanuhum intended to say is that he would chose povray NURBS to
export Blender Hair. Personnally I find sphere_sweep a fine compromise though by
far slower than the blender native option.

POV-Ray NURBS however, are a GREAT addition for other uses, and I indeed hope
that I will be able to integrate Lanuhum's exporter branch script lines inside
official version without breaking things.

THANKS a lot to Le Forgeron, Clipka, and the POV-Ray developers !


Post a reply to this message

<<< Previous 10 Messages Goto Latest 10 Messages Next 10 Messages >>>

Copyright 2003-2023 Persistence of Vision Raytracer Pty. Ltd.