> Are your meshes forming closed shapes? If a mesh forms a shaped surface without
> any back, any ray entering it get refracted and is considered traveling inside
> something with an ior of 1.2. Now, it encounter the second mesh, also having an
> ior of 1.2. So, the ior before and after the surface is the same resulting in no
> further refraction.

The meshes are not closed. Basically I started with a .OBJ file of the
Stanford Bunny. I then wrote a program that would remove the back of the
bunny, leaving me with only its front.

How could I fix this? Is there any command that allows me to work around
this?

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Tim Attwood <tim### [at] comcastnet> wrote:
> Probably should have inside_vector in the meshes just to be safe, as well. 

  "Just to be safe"? Why?

  I think it's better to understand what "inside_vector" does instead of
just spreading it around "just to be safe".

-- 
                                                          - Warp

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Shai <rec### [at] hotmailcom> wrote:
> The meshes are not closed. Basically I started with a .OBJ file of the
> Stanford Bunny. I then wrote a program that would remove the back of the
> bunny, leaving me with only its front.

  Given that the mesh is transparent how could you expect it to work
correctly if parts of the surface have been removed?

> How could I fix this? Is there any command that allows me to work around
> this?

  How do you expect POV-Ray to create a part of the mesh which isn't there?

-- 
                                                          - Warp

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Shai nous apporta ses lumieres en ce 18-04-2007 01:43:
>> Are your meshes forming closed shapes? If a mesh forms a shaped surface without
>> any back, any ray entering it get refracted and is considered traveling inside
>> something with an ior of 1.2. Now, it encounter the second mesh, also having an
>> ior of 1.2. So, the ior before and after the surface is the same resulting in no
>> further refraction.

> The meshes are not closed. Basically I started with a .OBJ file of the
> Stanford Bunny. I then wrote a program that would remove the back of the
> bunny, leaving me with only its front.
It would be beter to use the whole original .OBJ converted into a mesh.
You wrote a programm to remove the back, what a waste of your time :-(
Maybe you can alter it to replace the back with a flat face rather than just 
removing part of the object.

> How could I fix this? Is there any command that allows me to work around
> this?


Only "fix" that I can think of is not removing the back, or replacing with some 
flat face. That can't be done by POV-Ray, as your choped object is missing some 
parts.

-- 
Alain
-------------------------------------------------
'I never met a piece of chocolate I didn't like.'

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>  "Just to be safe"? Why?
I guess I wasn't being entirely clear...
>  I think it's better to understand what "inside_vector" does instead of
> just spreading it around "just to be safe".
The type of effect he's going for probably will end up requiring CSG,
and then he'll need inside_vector.  Inside_vector lets POV know where
the inside of a mesh is.

If you have two surfaces, a front and a rear, and you wish for refraction
to happen on them, one solution is for both of those surfaces to be
part of the same closed object assembled with CSG.

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>   Given that the mesh is transparent how could you expect it to work
> correctly if parts of the surface have been removed?
> --
>                                                           - Warp

I only want the ray to refract when it enters the object. The ray should not
be refracted again when it leaves the object through the back side. I didn't
know how to get this effect in POVray, so I thought it would be best if I
just removed the back of the object myself.

Post a reply to this message

Shai nous apporta ses lumieres en ce 19-04-2007 16:48:
>>   Given that the mesh is transparent how could you expect it to work
>> correctly if parts of the surface have been removed?
>> --
>>                                                           - Warp

> I only want the ray to refract when it enters the object. The ray should not
> be refracted again when it leaves the object through the back side. I didn't
> know how to get this effect in POVray, so I thought it would be best if I
> just removed the back of the object myself.

OK, but that is completely unrealistic and contrary to comon sence.

-- 
Alain
-------------------------------------------------
I abhor war and view it as the greatest scourge of mankind.
Thomas Jefferson

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Shai <rec### [at] hotmailcom> wrote:
> I only want the ray to refract when it enters the object. The ray should not
> be refracted again when it leaves the object through the back side. I didn't
> know how to get this effect in POVray, so I thought it would be best if I
> just removed the back of the object myself.

  So POV-Ray is thus behaving exactly like you wanted. What is, then, your
problem?

-- 
                                                          - Warp

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Alain <ele### [at] netscapenet> wrote:
> Shai nous apporta ses lumieres en ce 19-04-2007 16:48:
> >>   Given that the mesh is transparent how could you expect it to work
> >> correctly if parts of the surface have been removed?
> >> --
> >>                                                           - Warp
>
> > I only want the ray to refract when it enters the object. The ray should not
> > be refracted again when it leaves the object through the back side. I didn't
> > know how to get this effect in POVray, so I thought it would be best if I
> > just removed the back of the object myself.
>
> OK, but that is completely unrealistic and contrary to comon sence.
>
> --
> Alain
> -------------------------------------------------
> I abhor war and view it as the greatest scourge of mankind.
> Thomas Jefferson

I know, but I'm not going for realism here :)

Nevertheless, is there any way to achieve this effect without me having to
remove the back of the object?

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Shai nous apporta ses lumieres en ce 20-04-2007 07:01:
> Alain <ele### [at] netscapenet> wrote:
>> Shai nous apporta ses lumieres en ce 19-04-2007 16:48:
>>>>   Given that the mesh is transparent how could you expect it to work
>>>> correctly if parts of the surface have been removed?
>>>> --
>>>>                                                           - Warp
>>> I only want the ray to refract when it enters the object. The ray should not
>>> be refracted again when it leaves the object through the back side. I didn't
>>> know how to get this effect in POVray, so I thought it would be best if I
>>> just removed the back of the object myself.
>> OK, but that is completely unrealistic and contrary to comon sence.

>> --
>> Alain
>> -------------------------------------------------
>> I abhor war and view it as the greatest scourge of mankind.
>> Thomas Jefferson

> I know, but I'm not going for realism here :)

> Nevertheless, is there any way to achieve this effect without me having to
> remove the back of the object?


You can replace it with a flat surface. There will be a refraction, but it will 
be uniform. It may be the best compromise available to you.
For that, you can rework your removal tool into a replacing one, or you can 
difference the mesh with a plane. For that last one, the mesh must be completely 
closed and every faces must be correctly oriented, the inside vectors all toward 
the actual inside of the mesh.

-- 
Alain
-------------------------------------------------
Commercialism: Let's package this shit.

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