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14 Nov 2024 00:21:12 EST (-0500)
  Question about planes and bicubic patch... (Message 1 to 5 of 5)  
From: Ed Ambrose
Subject: Question about planes and bicubic patch...
Date: 21 Sep 1999 14:09:09
Message: <37e7c9c5@news.povray.org>
I'm trying to design a canoe using Povray so my model contains a plane (i.e.
the water) and a bunch of bicubic patches.  However, if I set the plane at
the correct waterline the inside of the canoe fills with water (i.e. the
plane is visable inside the bicubic patchs that form the canoe).  Any
thoughts on how I could fix this?

Thanks

Ed A.


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From: Bob Hughes
Subject: Re: Question about planes and bicubic patch...
Date: 21 Sep 1999 15:39:44
Message: <37e7df00@news.povray.org>
Have you tried using 'inverse' with a 'difference' of the canoe mesh
and plane?
Meshes (bicubic, triangles, etc.) don't CSG well, if at all.
Other messy option would be to reproduce the basic canoe shape using
somethings else, like a set of blob components, and difference that
from the plane.

Bob

Ed Ambrose <eam### [at] tricordcom> wrote in message
news:37e7c9c5@news.povray.org...
> I'm trying to design a canoe using Povray so my model contains a
plane (i.e.
> the water) and a bunch of bicubic patches.  However, if I set the
plane at
> the correct waterline the inside of the canoe fills with water (i.e.
the
> plane is visable inside the bicubic patchs that form the canoe).
Any
> thoughts on how I could fix this?
>
> Thanks
>
> Ed A.
>
>


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From: Ken
Subject: Re: Question about planes and bicubic patch...
Date: 21 Sep 1999 19:34:01
Message: <37E8153B.A24AFE29@pacbell.net>
Bob Hughes wrote:
> 
> Have you tried using 'inverse' with a 'difference' of the canoe mesh
> and plane?
> Meshes (bicubic, triangles, etc.) don't CSG well, if at all.
> Other messy option would be to reproduce the basic canoe shape using
> somethings else, like a set of blob components, and difference that
> from the plane.
> 
> Bob

 This may sound like a strange suggestion but that is what I am good at :)

 Triangle and bicubic patches as my learned colleague Bob has pointed out
do not work well ( or at all in most cases) in CSG operations. The only
real exception to this are height fields. With a little effort I propose
that it might be possible to give your existing canoe a greyscale gradient
pigment, render it, then use the image produced as a height field. You
could then use this height field in a CSG operation to hollow out the plane
that is your water. A bit cumbersome but certainly not outside the realms
of possibility.

-- 
Ken Tyler

See my 1000+ Povray and 3D Rendering and Raytracing Links at:
http://home.pacbell.net/tylereng/index.html


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From: Leroy Whetstone
Subject: Re: Question about planes and bicubic patch...
Date: 30 Sep 1999 22:32:50
Message: <37EFEB7F.B2A06496@janics.com>
I haven't use bicudic patches much. Just a thought since you've got the canoe
done,
How much trouble would it be to take copy the canoe data and flatten it out?
Leaving the impression ya want at the depth ya want.
I've made a canoe but I use lathe and CGS to put it in the water.


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From: Fabien Hénon
Subject: Re: Question about planes and bicubic patch...
Date: 16 Oct 1999 16:22:56
Message: <36EF3166.90B8D92E@club-internet.fr>
Why not use an image_map with a transparent shape of your canoe for the plane.
It may require some work but it should do.


Fabien




> I haven't use bicudic patches much. Just a thought since you've got the canoe
> done,
> How much trouble would it be to take copy the canoe data and flatten it out?
> Leaving the impression ya want at the depth ya want.
> I've made a canoe but I use lathe and CGS to put it in the water.


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