POV-Ray : Newsgroups : povray.beta-test : v3.8 Clean up TODOs. f_superellipsoid() / shadow cache. : Re: v3.8 Clean up TODOs. f_superellipsoid() / shadow cache. Server Time
25 Sep 2022 10:26:17 EDT (-0400)
  Re: v3.8 Clean up TODOs. f_superellipsoid() / shadow cache.  
From: William F Pokorny
Date: 19 Apr 2020 18:13:06
Message: <5e9cccf2$1@news.povray.org>
On 4/18/20 4:12 PM, jr wrote:
> hi,
> 
> William F Pokorny <ano### [at] anonymousorg> wrote:
>> ...
>> Trick helps enough, I wonder if some other inbuilts could benefit from a
>> float over double option too.
> 
> does the .. cost of extra speed, in context, matter so much?  asking because
> (and perhaps I'm completely off-track) only today was a post (by user 'guarnio')
> where the problem is/was the range of float not being enough.
> 

Not trying to be flippant, but I think it does when it does, and doesn't 
when it doesn't. It's a judgement.

The scale and range of a scene with respect to accuracy as an issue is 
always there relative to the accuracy you have available.

With functions and isosurfaces, the speed of even very fast inbuilt 
functions matters because you mostly want to combine them with other 
functions to create whatever. The performance of all those functions 
mixed together mathematically is what can quickly get out of hand to the 
point of being practically unusable performance wise.

With functions and isosurfaces, we already have an object with user 
variable accuracy via the accuracy value passed which is often << 7/8 
digits (I typically use 0.0005). I've done some limited testing and the 
isosurface solver and - partly due the types of functional input - it 
cannot deliver more than 6-7 digits of accuracy max as a rule sometimes 
less. With other object types and solvers you can get up in the 11/12 
digit ranges though often less. All at doubles.

Relatedly, I believe in going after better performance continually in 
software tools - otherwise you're on the slippery slope to poky. :-)

Bill P.


Post a reply to this message

Copyright 2003-2021 Persistence of Vision Raytracer Pty. Ltd.