Forgive the weird subject of this posting, but that's as close as I get to
the origin of the problem.

I use a transparant difference to create a spherical shell. Visible through
this shell is a part of a transparant cyclinder. For some reason the rays
that pass through both objects end up with the wrong color.

The following code is a minimum example that exhibits this problem. It was
rendered with version 3.1g.watcom.win32 on Windows 95 SE.

Any ideas anybody? Am I right in the assumption that this is a bug, or am I
overlooking something obvious?

Berend Meijer

// **********************************************

// A nearly transparant vertical cyclinder ...

cylinder
{
  <0,-1,0>, <0,0,0>, 0.5
  pigment
  {
    color <1,1,1>
    filter 0.8     // <-- This seems to be (part of) the problem
  }
}

// ... with on top a nearly transparant spherical shell ...

difference
{
  sphere
  {
    <0,0.5,0>, 0.5
  }
  sphere
  {
    <0,0.5,0>, 0.49
  }
  pigment
  {
    color <1,1,1>
    filter 0.9
  }
}

// ... against a white background

plane
{
  <0,0,-1>, -2
  pigment
  {
    color <1,1,1>
  }
}

// **********************************************

light_source
{
  <3,3,0>
  color <1,1,1>
}

camera
{
  location <0,1,-3>
  look_at <0,0,0>
}

--

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