POV-Ray : Newsgroups : povray.general : Another Spline Inconsistency Server Time
6 Aug 2024 19:33:55 EDT (-0400)
  Another Spline Inconsistency (Message 1 to 4 of 4)  
From: Rune
Subject: Another Spline Inconsistency
Date: 16 Feb 2002 06:54:39
Message: <3c6e487f@news.povray.org>
As shown in my post "Cubic spline question" the cubic spline used in
spline{} is completely different from the cubic spline used in prisms, yet
they go under the same name.

In this post I'll show a case of the opposite - two identical splines go
under completely different names.

The catmull_rom_spline used in sphere_sweeps is in fact exactly identical to
the cubic_spline used in prisms. Why do they have different names? I don't
know. It dates back to MegaPov of course, but POV-Ray 3.5 is not MegaPov.
Well, at least it should be rather easy to fix as it's just a matter of
changing the keyword I would think. The code below illustrates that the two
spline types are in fact the same.

camera {location 10*y look_at 0}
light_source {1000*y, color 1}
plane {y, 0 pigment {checker rgb 1.0, rgb 0.9}}
sphere_sweep {
   catmull_rom_spline
   8,
   <-2,0, 0>, 0.02,
   < 0,0,-2>, 0.02,
   < 4,0, 0>, 0.03,
   < 1,0, 1>, 0.01,
   < 0,0, 4>, 0.03,
   <-2,0, 0>, 0.02,
   < 0,0,-2>, 0.02,
   < 4,0, 0>, 0.03
   pigment {color <0,0,1>}
}
prism {
   cubic_spline
   0, 0.01
   8,
   <-2, 0>,
   < 0,-2>,
   < 4, 0>,
   < 1, 1>,
   < 0, 4>,
   <-2, 0>,
   < 0,-2>,
   < 4, 0>
   pigment {color <0,1,0>}
}

Rune
--
3D images and anims, include files, tutorials and more:
Rune's World:    http://rsj.mobilixnet.dk (updated Jan 20)
POV-Ray Users:   http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Webring: http://webring.povray.co.uk


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From: Ron Parker
Subject: Re: Another Spline Inconsistency
Date: 19 Feb 2002 16:20:21
Message: <slrna75gd4.cff.ron.parker@fwi.com>
On Sat, 16 Feb 2002 12:53:06 +0100, Rune wrote:
> The catmull_rom_spline used in sphere_sweeps is in fact exactly identical to
> the cubic_spline used in prisms. Why do they have different names? I don't
> know. It dates back to MegaPov of course, but POV-Ray 3.5 is not MegaPov.

And povray.general is not povray.beta-test.


-- 
#local R=<7084844682857967,0787982,826975826580>;#macro L(P)concat(#while(P)chr(
mod(P,100)),#local P=P/100;#end"")#end background{rgb 1}text{ttf L(R.x)L(R.y)0,0
translate<-.8,0,-1>}text{ttf L(R.x)L(R.z)0,0translate<-1.6,-.75,-1>}sphere{z/9e3
4/26/2001finish{reflection 1}}//ron.parker@povray.org My opinions, nobody else's


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From: Rune
Subject: Re: Another Spline Inconsistency
Date: 19 Feb 2002 16:59:45
Message: <3c72cad1@news.povray.org>
"Ron Parker" wrote:
> And povray.general is not povray.beta-test.

Right, and as it was not exactly a bug, and as there might be a reason for
the design, I deliberately didn't post to povray.beta-test. People have been
told often enough to discuss non-bug related 3.5 issues outside of
povray.beta-test, and that especially applies to feature requests, which my
message could be interpreted as.

However, I take it from your reply that a report in povray.beta-test would
be in place, and a such I will happily send.

Rune
--
3D images and anims, include files, tutorials and more:
Rune's World:    http://rsj.mobilixnet.dk (updated Feb 16)
POV-Ray Users:   http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Webring: http://webring.povray.co.uk


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From: Ron Parker
Subject: Re: Another Spline Inconsistency
Date: 19 Feb 2002 21:07:44
Message: <slrna76181.chh.ron.parker@fwi.com>
On Tue, 19 Feb 2002 22:59:25 +0100, Rune wrote:
> "Ron Parker" wrote:
>> And povray.general is not povray.beta-test.
> 
> Right, and as it was not exactly a bug, and as there might be a reason for
> the design, I deliberately didn't post to povray.beta-test. People have been
> told often enough to discuss non-bug related 3.5 issues outside of
> povray.beta-test, and that especially applies to feature requests, which my
> message could be interpreted as.
> 
> However, I take it from your reply that a report in povray.beta-test would
> be in place, and a such I will happily send.

Well, I think it's at least something that should be documented.

-- 
#local R=rgb 99;#local P=R-R;#local F=pigment{gradient x}box{0,1pigment{gradient
y pigment_map{[.5F pigment_map{[.3R][.3F color_map{[.15red 99][.15P]}rotate z*45
translate x]}]#local H=pigment{gradient y color_map{[.5P][.5R]}scale 1/3}[.5F
pigment_map{[.3R][.3H][.7H][.7R]}]}}}camera{location.5-3*z}//only my opinions


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