Paul Derbyshire wrote:

> What's new in version 3.1? Oddly enough search as I might I can't find
> this information on the POV home page. (And I'm sure not downloading 1.3
> megabytes without knowing whether there's anything really interesting
> added...)
> Please respond with either some information, or better yet a link to
> where I can read about what's new in 3.1.

  Chris Young, the Pov-Ray, team leader answered this question not to
long ago.

Here is what he had to say about what is new in Pov-Ray v3.1r1:

    1.1 What's New in POV-Ray 3.1?
Here is an overview of what is new in POV-Ray 3.1 since version 3.0.

    1.1.1 Media Replaces Halo & Atmosphere
The keywords halo and atmosphere have been totally eliminated with no
backwards compatibility of any kind provided. They have been replaced
by a new feature called media.  At the scene level, media acts as
atmospheric media for fog, haze, dust, etc.  On objects, media is not
part of texture like halo was. Object media is now part of a new
feature called interior.  Media is not just a rename for halo.  It is
a new model with some similar features of halo.
 BECAUSE POV-Ray 3.1 DISCONTINUES SOME 3.0 FEATURES
YOU MAY WISH TO KEEP 3.0 TO RENDER OLDER SCENES.

Any pattern type (bozo, wood, dents, etc.) may be used as a density
function for media.

New patterns spherical, cylindrical, planar, and boxed added for
pigment, normal, texture, and density.

New wave types cubic_wave and poly_wave Float have been added.

New object modifier interior{...}.  Interior contains information
about the interior of the object which was formerly contained in the
finish and halo parts of a texture. Interior items are no longer part
of the texture.  Instead, they attach directly to the objects. The
finish items moved are ior, caustic, fade_power, and fade_distance.
The refraction keyword is no longer necessary.  Any ior other than 1.0
turns on refraction.  These 5 finish keywords which are now part of
interior will still work in finish but will generate warnings.  Some
obscure texture_map statements with varying ior will not work.

Added reflection_exponent Float to finish to give more realistic
reflection of very bright objects.

    1.1.2 New #macro Feature
Add fully recursive and parameterized #macro directive.  Define like
this...
  #macro MyMacro (P1,P2,P3)   ...  #end
Invoke like this...
  MyMacro (5,x*5,MyTexture)
Note no '#' sign precedes invocation.  Macros can be invoked almost
anywhere. Parameters must be identifiers or any item that can be
declared, MyMacro(pigment{Green},MyObject) for example.
Added #local IDENTIFIER= STATEMENT as alternative to #declare to
create temporary local identifier in macros or include files.

    1.1.3 Arrays Added
Added multi-dimension arrays
  #declare MyArray=array[20]
 or
  #local PrivateArray=array[30]
 or
  #declare Rows=5; #declare Cols=4;
  #declare Table=array[Rows][Cols]
Added optional initializer syntax for arrays.
 #declare MyArray=array[2][3]{{1,2,3},{4,5,6}}
Subscripts start at 0.  Anything that can be declared may be in an
array. Arrays are initialized as null.  You must later fill each
element with values.
Added float functions for arrays.  Given #declare MyArray =
array[4][5] then dimensions(MyArray) is 2 and
dimension_size(MyArray,2) is 5.

    1.1.4 File I/O and other Directives
Added #fopen, #fclose, #read, and #write directives for user text
files.
Added #undef identifier directive.  Un-declares previously declared
identifier.  Works on locals or globals.
Added requirement that any directive which can end in a float or
expression must be terminated by a semi-colon.  Specifically this
means any #declare or #local of float, vector or color or the #version
directive.

    1.1.5 Additional New Features
Added Bezier splines to lathe and prism. The spline is made of
segments having four points each. Thus there are always four times the
number of  segments in a prism or lathe. A four point Bezier spline
uses 3rd order Bernstein blending functions which are sufficient for
smooth curves.
Added float constant clock_delta returns time between frames.




The new editor, that they added with this version is in my opinion worth
the download time. It has been completely redesigned and the features are
too
numerous to list. The new  "Media" feature, once you get used to it is
already
showing itself to have enormous bennifits. I recently saw a clouds over
water
scene unlike any I have ever seen with other versions of Pov-Ray. Check out
the images in povray.binaries.images I believe the title is Media Clouds.

Any more questions ?

Ken Tyler

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