I've lately noticed some really odd behavior in 3.7 ("odd" as compared to 3.62.)
Max_trace_level seems to be completely OFF or ON now, when its value is changed
between 1 and 2 (or anything higher than 2.) In other words, a value of 2
produces the same visual result as setting it to its maximum value, or so it
seems. The other odd thing is that the render statistics always return a 'Max
Level' of only 1, regardless of the max_trace_level setting or the number of
semi-transparent overlapping objects in a scene.

(This is in Windows XP, on a single_core AMD machine, using 32-bit v3.7 sse2.)

Here's a small test scene, with a switch for rendering in 3.62 vs. 3.7. Just
semi-transparent nested spheres.
----

// The switch...
#declare version_to_use = 2; // 1 for v3.62, 2 for v3.7

#if(version_to_use = 1)
global_settings{max_trace_level 5 assumed_gamma 2.2}

background {rgb .7}

#declare C=1;
#while(C<=40)
sphere{0,1
 scale .1 + .20*C
 pigment{rgbt <.1,1,.1,.99>}
 }
#declare C=C+1;
#end
#else
#end

#if(version_to_use = 2)
#version 3.7;
global_settings{max_trace_level 2 assumed_gamma srgb}

background {srgb .7}

#declare C=1;
#while(C<=40)
sphere{0,1
 scale .1 + .20*C
 pigment{srgbt <.1,1,.1,.99>}
 }
#declare C=C+1;
#end
#else
#end

// for both versions...
camera {
  perspective
  location  <1, 1, -25>
  look_at   <0, 0,  0>
  right     x*image_width/image_height
  angle 67
}

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Kenneth <kdw### [at] gmailcom> wrote:
> #declare C=1;
> #while(C<=40)
> sphere{0,1
>  scale .1 + .20*C
>  pigment{rgbt <.1,1,.1,.99>}
>  }
> #declare C=C+1;
> #end
> #else
> #end

POV-Ray 3.7 does not increase the recursion count when the object has
an ior of 1 (ie. the direction of the ray doesn't change.)

If you give those spheres an ior different from 1, you should get the
behavior you expect.

-- 
                                                          - Warp

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Thanks; Alain has also explained this in another post. It seems that I need to
re-read the 3.7 change log, to familiarize myself with the many subtle changes
that have occurred since 3.62. ;-) Some of these haven't yet made it into the
new documentation or wiki.

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On 04/06/2014 06:26 PM, Kenneth wrote:
> Some of these haven't yet made it into the
> new documentation or wiki.

so this is just a generalized dig ... right? (lol) or is it a reference 
to the max_intersections issue you reported in p.d.inbuilt? btw ... 
corrected it!

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James Holsenback <nom### [at] nonecom> wrote:
> On 04/06/2014 06:26 PM, Kenneth wrote:
> > Some of these haven't yet made it into the
> > new documentation or wiki.
>
> so this is just a generalized dig ... right? (lol) or is it a reference
> to the max_intersections issue you reported in p.d.inbuilt? btw ...
> corrected it!

Yeah, I'm guilty. :-P  Thanks for the quick correction!

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