POV-Ray : Newsgroups : povray.general : isosurface functions : Re: isosurface functions Server Time
4 Dec 2022 21:24:35 EST (-0500)
  Re: isosurface functions  
From: William F Pokorny
Date: 5 Mar 2022 04:33:14
Message: <62232e5a$1@news.povray.org>
On 3/4/22 10:19, Chris R wrote:
> Sorry, I should have been clearer in labeling the variables.  For any given
> object, Radius and Height are fixed values, while x, y, and z vary over the
> isosurface boundaries.  So, pow(y/Height,2) and sqrt(y/Height) both range
> between 0 at y=0 and 1 at y=Height.

Adding to what others have said.

Especially with contained by box, I'd recommend not putting container 
sides on any x,y or z plane at 0.0. There is often a small amount of 
noise in the ray-container intersection result. This means you might 
well be getting small negative values internally though you specified a 
0.0 container side value. Any negative 'y' values are a problem for the 
sqrt() function for example.

I usually try and center my final 'shape' about 0,0,0 such that the 
container ends up also centered at 0,0,0. You can also handle the 
potential for near zero negative values other ways - ie abs(y).

Bill P.


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