POV-Ray : Newsgroups : povray.advanced-users : Unexpected isosurface (dis)appearance : Re: Unexpected isosurface (dis)appearance Server Time
2 Jun 2023 01:59:50 EDT (-0400)
  Re: Unexpected isosurface (dis)appearance  
From: clipka
Date: 4 Aug 2018 09:40:02
Message: <5b65acb2$1@news.povray.org>
Am 04.08.2018 um 14:49 schrieb Bald Eagle:
> So, I was just starting a small scene to use clipped_by in, and something's
> going on with the isosurface that's making it very confusing and difficult to
> interpret.
> Using the first camera location, you can see that it looks like there is no
> "back" to the shape.  Using the second camera location from above, you can see
> that they are indeed whole shapes.
> I tried using open, interior_texture, a larger contained_by box{}, ....

Because isosurfaces can be arbitrarily complex, by default only the
first N intersections along the ray are computed. `clipped_by` handling
is done in a later stage, so if those N intersections are all outside
the `clipped_by` shape, no further intersections will be computed, and
the object will appear to have a hole there. The same also happens in
non-union CSG.

You can change N by specifying `max_trace N` in the isosurface block.
Alternatively, you can specify `all_intersections` to set N to the
maximum supported value.

The default for N is 1, the maximum is 10.

The higher N, the slower the isosurface will render.

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