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30 Jul 2024 00:29:03 EDT (-0400)
  fog and transparent open mesh (Message 1 to 3 of 3)  
From: CAD-Andi
Subject: fog and transparent open mesh
Date: 2 Jun 2010 19:45:01
Message: <web.4c06ec1fc3237a417fa521e30@news.povray.org>
I'm using 3.7.beta.37 and have a problem with fog and transparent open meshes.
I'm simulating the view out of a vehicle. The geometry I have Is fairly complex.
Everything is done with the "mesh" and "smooth triangle" commands. The problem I
have is that either fog is not visible through the windshield but is visible
through the open side window, or, if I put the inside vector on the other side
of the windshield the effect is reversed: Fog is visible through the windshield,
but not through the open side window. I tried the "hollow" command on the meshes
with no effect. I had similar issues with planes that have images with
transparent background mapped to them (landscape) but this got resolved when I
added the "hollow" function to the plane. Any suggestions?


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From: clipka
Subject: Re: fog and transparent open mesh
Date: 3 Jun 2010 06:02:45
Message: <4c077dc5$1@news.povray.org>
Am 03.06.2010 01:41, schrieb CAD-Andi:
> I'm using 3.7.beta.37 and have a problem with fog and transparent open meshes.
> I'm simulating the view out of a vehicle. The geometry I have Is fairly complex.
> Everything is done with the "mesh" and "smooth triangle" commands. The problem I
> have is that either fog is not visible through the windshield but is visible
> through the open side window, or, if I put the inside vector on the other side
> of the windshield the effect is reversed: Fog is visible through the windshield,
> but not through the open side window. I tried the "hollow" command on the meshes
> with no effect. I had similar issues with planes that have images with
> transparent background mapped to them (landscape) but this got resolved when I
> added the "hollow" function to the plane. Any suggestions?

When the camera is inside [or outside] a mesh (as defined via the 
inside_vector) POV-Ray has no way of telling where a ray leaves [or 
enters] the mesh except via intersections; your open window does not 
give such an intersection, so POV-Ray will think it is still inside.

There should be three ways (if not even more ;-)) to fix this issue:

(A) Assign the same interior (especially media) to the inside of the 
mesh as to the outside.

(B) Close the mesh technically, by adding some more triangles in the 
open window and assigning a perfectly transparent texture to them (i.e. 
make it just /look/ like the window is open).

(C) Make the mesh non-solid.


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From: CAD-Andi
Subject: Re: fog and transparent open mesh
Date: 3 Jun 2010 17:00:01
Message: <web.4c0817587ab6a25dbf952ed30@news.povray.org>
Thanks! Adding interior {} to the material of the mesh actually took care of it.
Now I see my fog everywhere. I don't know if it is the cleanest solution, but it
sure works for me! Thanks!


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