Am 15.11.2012 15:40, schrieb Bruno Cabasson:

> 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) ?

Yes, for some object types it is absolutely necessary, at least for the 
internal math.

Likewise, if we were using single-precision, coincident surface issues 
would be even worse. (A similar problem exists in 3D games, called 
"Z-fighting".)


> why would single precision not be sufficient for :
>
>      RGBFT values storage, which might imply :
>          radiosity/photon maps elaboration ?
>          texturing and lighting ?

Absolutely. That's why color storage and math already /is/ 
single-precision ;-). (An exception is color storage at SDL level, but 
that's only because the SDL doesn't differentiate between colors and 
vectors.)

>      media (even though it uses integration methods)

Not sure what you mean by this. As far as color math is concerned, see 
above.

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