I know there is a tool to create meshes from parametric functions and thereby
speeding up rendering, but is there also one to create meshes from the implicit
functions used in isosurfaces?

-Mike

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"SharkD" <nomail@nomail> wrote:
> I know there is a tool to create meshes from parametric functions and thereby
> speeding up rendering, but is there also one to create meshes from the implicit
> functions used in isosurfaces?
>
> -Mike

I managed to find one here:

http://news.povray.org/povray.binaries.scene-files/message/%3C47be20ab%40news.povray.org%3E/#%3C47be20ab%40news.povray.
org%3E

This tutorial describes them, but the links are dead:

http://www.econym.demon.co.uk/isotut/approx.htm

-Mike

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Wasn't it SharkD who wrote:
>I know there is a tool to create meshes from parametric functions and thereby
>speeding up rendering, but is there also one to create meshes from the implicit
>functions used in isosurfaces?

There is one, but it's usually a lot slower than using actual 
isosurfaces, so it's much less useful.

See: http://www.econym.demon.co.uk/isotut/approx.htm

The code for all the images, including both versions of the macro, is in 
the ZIP file at the bottom of the page.

-- 
Mike Williams
Gentleman of Leisure

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Mike Williams <nos### [at] econymdemoncouk> wrote:
> The code for all the images, including both versions of the macro, is in
> the ZIP file at the bottom of the page.
>
> --
> Mike Williams
> Gentleman of Leisure

OK, thanks. The box with the ZIP file looked like a banner advertisement, so I
overlooked it.

-Mike

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"SharkD" <nomail@nomail> wrote:
> Mike Williams <nos### [at] econymdemoncouk> wrote:
> > The code for all the images, including both versions of the macro, is in
> > the ZIP file at the bottom of the page.
> >
> > --
> > Mike Williams
> > Gentleman of Leisure
>
> OK, thanks. The box with the ZIP file looked like a banner advertisement, so I
> overlooked it.
>
> -Mike

Please see the scene files group for the trouble I am having.

-Mike

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"SharkD" <nomail@nomail> wrote:
> Please see the scene files group for the trouble I am having.
>
> -Mike

Bump. Does anyone have a clue what is going wrong?

-Mike

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>> Please see the scene files group for the trouble I am having.
>>
>> -Mike
>
> Bump. Does anyone have a clue what is going wrong?

I took a look at it... and no, I'm not sure why it's not working.
=(
It's probably something to do with the accuracy (gradient) of
the approximating macros, but that's a guess.

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Mike Williams <nos### [at] econymdemoncouk> wrote:
> There is one, but it's usually a lot slower than using actual
> isosurfaces, so it's much less useful.

I hope it's not slower, because that (as well as the visual artifacts that occur
frequently when using isosurfaces) is the primary reason I want to use it.

-Mike

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"Tim Attwood" <tim### [at] comcastnet> wrote:
> I took a look at it... and no, I'm not sure why it's not working.
> =(
> It's probably something to do with the accuracy (gradient) of
> the approximating macros, but that's a guess.

OK, thanks for taking a look at it. Too bad it doesn't work in this case.

-Mike

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Wasn't it SharkD who wrote:
>Mike Williams <nos### [at] econymdemoncouk> wrote:
>> There is one, but it's usually a lot slower than using actual
>> isosurfaces, so it's much less useful.
>
>I hope it's not slower, because that (as well as the visual artifacts 
>that occur
>frequently when using isosurfaces) is the primary reason I want to use it.

As mentioned on my page, there are some circumstances where you might 
gain speed advantages. With real isosurfaces, the parse time is 
negligible and the render time is large. With the approximation macro, 
the parse time is large and the render time is small. If you need to 
render the same object more than once (e.g. in each frame of an 
animation) then you can save the mesh data after it has been parsed 
once.

-- 
Mike Williams
Gentleman of Leisure

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