This may be the wrong news group for this but is it possible? I mean ok I've
got a bicubic patch object but I just want a hollow outline of the shape
rather than a solid is it possible to render this or am I barking up the
wrong tree here?

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The \"D\" wrote:
> 
> This may be the wrong news group for this but is it possible? I mean ok I've
> got a bicubic patch object but I just want a hollow outline of the shape
> rather than a solid is it possible to render this or am I barking up the
> wrong tree here?

Do you mean something like a wireframe view of the object?

-- 
Ken Tyler

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In article <3df23931@news.povray.org>,
 "The \"D\"" <dav### [at] gmxnet> wrote:

> This may be the wrong news group for this but is it possible? I mean ok I've
> got a bicubic patch object but I just want a hollow outline of the shape
> rather than a solid is it possible to render this or am I barking up the
> wrong tree here?

It is not possible. POV does not know about the "outline" of the object, 
only about ray intersections with it. There are a couple things you 
could do:
The MegaPOV unofficial version had a post-process feature with a 
find_edges filter, you could use that to mark pixels on or near an edge. 
MegaPOV is pretty out of date though.

Somewhere in the scene file groups on this server is a scene which used 
functions to do the same thing in POV 3.5.

You could give the object a pure white texture with ambient 1 in the 
texture, and use a pure black background. Then render with antialiasing, 
and use an image editor to select the background and fill it with white.
The antialiased outlines won't match the background color, so they will 
be left behind (if your fill command has a threshold, set it to 0).

You could then use the threshold command to make the outline pure black, 
and you have a black outline of the object on a white background. You 
could blur the image first to make the lines thicker, this may be 
necessary to get a solid line, and could also avoid the need for 
antialiasing.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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Ken wrote:
> Do you mean something like a wireframe view of the object?

No Just the outline. In this case it's a 2d-ish image (at least it is from
the perspective of the viewer) I'm just wanting the outline of the shape
rather than a solid shape.

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Christopher James Huff wrote:

> It is not possible. POV does not know about the "outline" of the object,
> only about ray intersections with it. There are a couple things you
> could do:
> The MegaPOV unofficial version had a post-process feature with a
> find_edges filter, you could use that to mark pixels on or near an edge.
> MegaPOV is pretty out of date though.
> Somewhere in the scene file groups on this server is a scene which used
> functions to do the same thing in POV 3.5.



> You could give the object a pure white texture with ambient 1 in the
> texture, and use a pure black background. Then render with antialiasing,
> and use an image editor to select the background and fill it with white.
> The antialiased outlines won't match the background color, so they will
> be left behind (if your fill command has a threshold, set it to 0).

Hmmm.... if I can't get away with a solid object I might try something like
that. But this method and the one below seem a bit more work than I want to
put in to what I'm doing at the moment. Though this particular one doesn't
seem to too bad. And if I want a coloured outline could I render the object
with color x and ambient 1 and do the same thing?

> You could then use the threshold command to make the outline pure black,
> and you have a black outline of the object on a white background. You
> could blur the image first to make the lines thicker, this may be
> necessary to get a solid line, and could also avoid the need for
> antialiasing.

Threshold command? Is this in povray or in some image editor? And would I
blur in povray or my image editor ?

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In article <3df2c57b@news.povray.org>,
 "The \"D\"" <dav### [at] gmxnet> wrote:

> Hmmm.... if I can't get away with a solid object I might try something like
> that. But this method and the one below seem a bit more work than I want to
> put in to what I'm doing at the moment. Though this particular one doesn't
> seem to too bad. And if I want a coloured outline could I render the object
> with color x and ambient 1 and do the same thing?

If you want a different color with this method, your best bet is to just 
modify the final outline image. Once you have a solid black outline, 
modifying to be a different color should be easy.


> Threshold command? Is this in povray or in some image editor? And would I
> blur in povray or my image editor ?

It's a common filter in image editors. You'd do the blurring in an 
editor as well. The idea is that you start out with an image that is 
white where the object is and black everywhere else, then blur it to get 
"in-between" areas at the boundaries. Then you replace the black with 
white (or the other way around), and use a threshold filter to make the 
edge area solid.

You could do it in POV, but it takes more work. If you give us some more 
information on what you are trying to do, we might be able to suggest a 
better way.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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"The "D"" <dav### [at] gmxnet> wrote in message
news:3df23931@news.povray.org...
> This may be the wrong news group for this but is it possible? I mean ok
I've
> got a bicubic patch object but I just want a hollow outline of the shape
> rather than a solid is it possible to render this or am I barking up the
> wrong tree here?

At least in some cases a hollow outline
of  the bicubic patch object is defined by its four border curves.
In this case you can build an outline object easily with pov,
since these curves are defined directly by patch control points.

Gleb

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