"Bruno Cabasson" <bru### [at] cabassoncom> wrote:
> Hi all!
>
> Considering that many 3D applications (eg games) use single precision for their
> renders, I am wondering where we really need double precision for 'normally'
> sized scenes. I mean scenes that do not mix microscopic and gigantic distances.
>
> For sure, if the dynamic is huge, we absolutely need double precision, at least
> for object coordinates. But, if the dynamic in distances is reasonable, is it
> mandatory to use double precision for the following features :
>
>     ray - bounding box intersection tests ?
>     ray - object intersection computation ?
>     others (TBD) ?
>
[snip]
>
> What do you think ? Has the subject already been debated here ?

The dynamic doesn't even have to be huge.  See:

http://news.povray.org/povray.binaries.images/thread/%3Cweb.47e40ce72d3a644685de7b680@news.povray.org%3E/?ttop=304745&t
off=500

Since the error was not lighting-related, I don't think the 37,417 POV-unit
distance to the light source should be considered in the dynamic.  What sort of
dynamic do you have in mind?

POV-Ray does not seem suited to single precision.  Perhaps it is the nature of
mathematically defined shapes that they require higher precision than mesh-based
systems.

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