POV-Ray : Newsgroups : povray.newusers : gradient question Server Time
5 Sep 2024 10:25:32 EDT (-0400)
  gradient question (Message 11 to 12 of 12)  
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From: Trevor Quayle
Subject: Re: gradient question
Date: 19 Sep 2001 19:05:14
Message: <3ba924aa@news.povray.org>
I see what you mean now.  I have been running POV 3.5 in Windows,
unfortunately I don't know much about other OS/s.  Maybe you should post
your problem again with Unix in the subject and someone who knows more about
the other systems can help.
BTW try not posting .tga in p.b.i, they are quite large and someone is
likely to complain.  Use .jpg if you can.
Sory I can't help more.

-tgq


--
camera{location z*13look_at 0}light_source{15 15looks_like{sphere{0 10
}pigment{rgb 1}finish{ambient 15}}}union{torus{3,0.5rotate x*90}cone{y
*4,.5,-y*8,0}cone{-x*4,.5,x*8,0}pigment{rgb<.7,.6,.4>}finish{ambient 0
diffuse 0reflection{1fresnel on metallic 1}}interior{ior 25}rotate 15}
plane{y,-7pigment{checker rgb 0rgb 1scale 4}finish{diffuse.1}}//   TGQ


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From: Mike Williams
Subject: Re: gradient question
Date: 20 Sep 2001 00:21:32
Message: <IdxZqBAoEPq7Ew1L@econym.demon.co.uk>
Wasn't it Lothar Esser who wrote:
>Hi,
>   at the risk of embarrassing myself: I have a question about gradient
>in a pigment statement. What I want to do is to colour a cylinder which
>is not necessarily aligned with x,y,z or any simple combination of it
>from one end to the other with a simple gradient. For some reason an
>arbitrary vector in the gradient statement seems to be ignored.
>A statement like
>   cylinder {
>       <-1,-1,0>, <1,1,0>, 0.2
>       texture { pigment { gradient <1,1,0> color_map { [ 0.0 color rgb
>1] [1.0 color rgb <0,0,1>] } } } ... etc
>works but if I have a cylinder with the end points like <-0.1,-1,0>,
><0.1,1,0> then I cannot figure out what the correct
>gradient vector is: gradient <0.2,2,0> does not work.

I think it was a bug. It's fixed in POV_Ray 3.5b2.

In 3.5b2 both <0.1,1,0> and <0.2,2,0> work correctly.

(The only snag is that the gradient pattern is different in 3.5 in that
the colours always cycle in the same direction, whereas in 3.1 and all
previous versions the colours cycle in the opposite direction on the
other side of the origin.)

-- 
Mike Williams
Gentleman of Leisure


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