Hello all,

like to rethrow this theme to hopefully get some comments from you, or from
a developper...

The above behavior source is in "lightning.cpp". The variables meaning are:
- Jitter_Raw_Normal: is the normal vector of the surface.
- Jitter_Normal: is the normal vector of the disturbed surface
(normal{bozo})
- Ray->Direction: is the vector of incomming light
- New_Ray->Direction: is the vector of the reflected light

-----------
01    VDot(n,Ray->Direction, Jitter_Normal);
02    n *= -2.0;
03    VAddScaled(New_Ray.Direction, Ray->Direction, n, Jitter_Normal);
04    /* Nathan Kopp & CEY 1998 - Reflection bugfix
05      if the new ray is going the opposet direction as raw normal, we
06      need to fix it.
07      */
08    VDot(n, New_Ray.Direction, Jitter_Raw_Normal);
09    if (n < 0.0)
10    {
11      /* It needs fixing.  Which kind? */
12      VDot(n2,New_Ray.Direction,Jitter_Normal);
13      if (n2 < 0.0)
14      {
15        /* reflected inside rear virtual surface. Reflect Ray using
16 Raw_Normal */
17        VDot(n,Ray->Direction,Jitter_Raw_Normal);
18        n *= -2.0;
19        VAddScaled(New_Ray.Direction, Ray->Direction,
n,Jitter_Raw_Normal);
20      }
21      else
22      {
23        /* Double reflect NRay using Raw_Normal */
24        /*VDot(n,New_Ray.Direction,Jitter_Raw_Normal); - kept the old n
25 around */
26        n *= -2.0;
27        VAddScaledEq(New_Ray.Direction, n, Jitter_Raw_Normal);
28      }
29    }
30    VNormalizeEq(New_Ray.Direction);
-------------

My problem happens when condtion on line 13 gets true, this happens when
incomming ray is behind the disturbed surface Jitter_Normal. The programmer
decided to reflect incomming ray on non-disturbed surface what creates the
fully mirror effect.
The more the normal is disturbed (big bump_size) so bigger is the
probability that incomming ray can be behind disturbed normal.
Why not apply Double reflection in this case too as on line 23-27?

Should I better post this in "bugreports"?

Please help me understand...
zuegs

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