POV-Ray : Newsgroups : povray.advanced-users : Blend_Map problem Server Time
30 Jul 2024 16:24:16 EDT (-0400)
  Blend_Map problem (Message 1 to 4 of 4)  
From: Jeff Lee
Subject: Blend_Map problem
Date: 17 May 1999 09:49:21
Message: <37401051.0@news.povray.org>
Hi, all,

I'm trying to create a fairly complex texture, and past a certain point,
POV-Ray complains with "error: Blend_Map too long".  How long can a
"Blend_Map" be, and are there any ways around the limitations?  


-- 
Jeff Lee         shi### [at] gatenet        http://www.gate.net/~shipbrk/

  "The only thing that helps me maintain my slender grip on reality
  is the friendship I share with my collection of singing potatoes."


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From: Bob Hughes
Subject: Re: Blend_Map problem
Date: 17 May 1999 10:20:33
Message: <374017AB.A2EF7827@aol.com>
Should be 2 to 256 possible entries into the map.


Jeff Lee wrote:
> 
> Hi, all,
> 
> I'm trying to create a fairly complex texture, and past a certain point,
> POV-Ray complains with "error: Blend_Map too long".  How long can a
> "Blend_Map" be, and are there any ways around the limitations?
> 
> --
> Jeff Lee         shi### [at] gatenet        http://www.gate.net/~shipbrk/
> 
>   "The only thing that helps me maintain my slender grip on reality
>   is the friendship I share with my collection of singing potatoes."

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/homepage.htm
 mailto://inversez@aol.com?Subject=PoV-News


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From: Ron Parker
Subject: Re: Blend_Map problem
Date: 17 May 1999 11:10:11
Message: <37402343.0@news.povray.org>
On Mon, 17 May 1999 12:49:24 GMT, Jeff Lee wrote:
>Hi, all,
>
>I'm trying to create a fairly complex texture, and past a certain point,
>POV-Ray complains with "error: Blend_Map too long".  How long can a
>"Blend_Map" be, and are there any ways around the limitations?  

frame.h sets MAX_BLEND_MAP_ENTRIES to 256.  You can probably increase
it and recompile POV-Ray.  If you want an ugly workaround without 
recompiling, you could probably use an extra layer of mapping like so:

sphere {0, 1 
  texture {
    pigment {
      gradient y pigment_map {
        [.5 gradient y pigment_map {
          [0 color red 1]
          [.25 color rgb <1,1,0>]
          [.5 color green 1] 
          }]
        [.5 gradient y pigment_map {
          [.5 color green 1]
          [.75 color rgb <0,1,1>]
          [1 color blue 1]
          }]  
        }
      }
    finish {ambient .3}
    }
  }


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From: Jeff Lee
Subject: Re: Blend_Map problem
Date: 17 May 1999 16:08:06
Message: <37406916.0@news.povray.org>
par### [at] fwicom (Ron Parker) wrote:
>
> frame.h sets MAX_BLEND_MAP_ENTRIES to 256.

Well, that would explain it.  


> If you want an ugly workaround without 
> recompiling, you could probably use an extra layer of mapping like so:

> sphere {0, 1 
>   texture {
>     pigment {
>       gradient y pigment_map {
>         [.5 gradient y pigment_map {
>           [0 color red 1]
>           [.25 color rgb <1,1,0>]
>           [.5 color green 1] 
>           }]
>         [.5 gradient y pigment_map {
>           [.5 color green 1]
>           [.75 color rgb <0,1,1>]
>           [1 color blue 1]
>           }]  
>         }
>       }
>     finish {ambient .3}
>     }
>   }

Hmmm.  Interesting way of handling it!  And it may be ugly, but at least
it'll run on unmodified versions of POV-Ray.  Many thanks, Ron!


-- 
Jeff Lee         shi### [at] gatenet         http://www.gate.net/~shipbrk/


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