Hi all!

I've been playing with this for some time now and just can't seem to solve
it, so I'm posting the question here.  Don't know if new users gets much
traffic though, so if there's no response in a few days I might post into
general.

Here's my problem: since I'm simply crazy, I'm trying to convert a mess of
very old (v0.5-v2) scene files to the 3.6 language.  Why?  Just because.
Even when using the version directive to get old files to parse, some things
just don't render correctly because of changes in the engine; for example,
some glasses, and gradient patterns...  So I want to convert the language in
the old files so the render correctly under 3.6 and hopefully future
versions.  Granted, nothing can be perfect, but v1 compatibility will be
phased out much sooner that v3.6 compatibility will.  Right?

This is the first hurdle I haven't been able to get around.  Something
changed with normals between 3.1 and 3.5, and it's really screwing around
with the one texture I've got.  This is from an awesome Mike Miller scene
file (kudos to those who can figure out which one!).  The code below is just
from the simple boilerplate scene with some extra stuff removed (I'd post
links to images but my webserver no likey me at the moment).  Render it with
the version directive intact and you'll see what I *want* to get...  A
sphere, with some gentle, um, horizontal ripples (latitudinal?  whatever).
You can see the crests and troughs without a problem, and the phong
highlight is nicely distributed just as you'd expect it to be.

Now render it without the version override.  Or, for sake of argument, with
#version 3.5; you'll see the difference immediately.  The normal appears to
flatten out, resulting in ugly green and black(ish) bands without any
highlight left.  I can't figure out exactly what's happening here - even if
the normal did *flatten*, then I should still get something of a highlight,
this looks like it's killing the whole finish.

I'm sure part of it has to do with the odd scaling factor, but this is what
he originally used, and I don't know how to accurately recreate it with
different values.  I've tried reordering the pigment / finish / normal
blocks, and using the no_bump_scale keyword, with no effect.  It's not just
like it's a parsing issue / difference, because you can wrap the definitions
with #version tags and it does no good.  The scene *must* be in a pre- 3.5
version state when rendering begins (i.e. that's why version at the end of
the file works), and codewise, I can see why in normal.cpp; it's checking
for version > 310 and applying a warp / unwarp around the normal
perturbation.  Unfortunately, I don't know what the warp / unwarp is doing;
I haven't specified any warp parameters, is there some default I should know
about?

Don't know what else to try here - I don't want to leave the scene in v3.1
mode; it kinda defeats the purpose of a 3.6 conversion, and I don't know
what other 3.5-6 features it disables.  I've searched through the
newsgroups, but can't seem to find anything relating to this, nor can I find
an old changelog from version 3.1 to 3.5 that might tell me what features
changed.  So, if ANYONE know what's going on here and how to get around it
(without #version 3.1; :)) I'd really appreciate it.

Thanks!
-D

Example scene:
#include "colors.inc"

camera {
  location  <0.0, 0.5, -4.0>
  direction 1.5*z
  right     x*image_width/image_height
  look_at   <0.0, 0.0,  0.0>
}

light_source {
  <0, 0, 0>            // light's position (translated below)
  color rgb <1, 1, 1>  // light's color
  translate <-30, 30, -30>
}

#declare Test_Texture =
texture {
   pigment {
      color DarkGreen
   }
   finish {
      ambient 0.350
      diffuse 0.800
      phong 1
      phong_size 60
      crand 0.040
   }
   normal {
      waves .800
      frequency .050
      //no_bump_scale
   }
   scale <10, .001, 10>  // a little smaller than actual to show more
surface waves
}

sphere { <0,0,0>, 1
   texture {
      Test_Texture

   }

}

// REVERT TO VERSION 3.1 TO RENDER AS DESIRED
#version 3.1;

Post a reply to this message