On Mon, 20 Apr 1998 16:39:01 -0400, ?
<hor### [at] popserviceohio-stateedu> wrote:

>When using radiosity, POV-Ray will automatically use
>mosaic previews during rendering to help the radiosity adapt to the
>particulars of the scene.  

Correction: it automatically uses one mosaic preview, at 8x8.  This is
important.

>If you set brightness to any value other than 3.3 it will render
>correctly during the mosaic passes, but when the scene is traced at
>original resolution (1x1) the brightness will default back to 3.3

Mosaic passes?  By default, as I said, it only does one.  If you
specify more than one, does the brightness bug happen in the second
pass, or only in the last (1x1) pass?  Make sure you specify a
start/end of 8/4, or POV will second-guess you.

Here's what I think it is:  after the first pass (by default, the only
mosaic pass) POV takes the average gray from all of the passes and
uses it to scale the brightness value.  Problem is, the statement it
scales the brightness with is this: (from render.c)

opts.Radiosity_Brightness = 3. / gather_gray;

See that 3?  What does the 3 mean?  I don't know either.  It should
probably read

opts.Radiosity_Brightness /= gather_gray;

Unfortunately, I'm in the midst of a job change, so I had to give up
my compiling/rendering machine for a while.  If someone could test
this, I'd appreciate it.

>I posted this before, but noone took any interest in it, marginalizing
>the problem by blaming my "buggy PC" or telling me how "experimental"
>radiosity is in POV-Ray.  Experimental or not, a bug is a bug is a bug! 

I'm not sure whether you're talking about me or not.  Let me stress
that my bringing up the "experimentalness" of radiosity was to justify
the fact that nobody here has spent much time trying to work on it,
not to justify a bug.  Bugs should be fixed, even in experimental
features.

>It seems as if I posted on a legitimate bug in the program only to be
>met by responses telling me "I don't know what I'm talking about" or
>that I should just "shut up and use the UNIX version."  Or basically
>that none of my posts would be taken seriously until I had "gained
>respect in this newsgroup."

I assume the newsgroup you're talking about is cgrr.  This is a
different newsgroup, with different rules.  Please don't color us with
the same brush you use for them, and don't assume that we saw the
earlier exchange.

>It is sad that I had to take on a rude tone to get any responses,
>because I know what I have found, and I know it is for real, and I was
>frustrated to get apathetic responses from a group of people that are
>supposed to know the stuff inside and out.  I'm not another 15-year-old
>that doesn't understand ray-tracing and hasn't read the documentation,
>but I'm being treated like one.

It _is_ kinda hard to find a bug without knowing what you're looking
for.  Note, too, that this bug isn't even in the radiosity code per
se.  It's in one of the main render loops.  See how easy it got when
we had a description to go on?

Post a reply to this message