[Bf-funboard] Volumetric normals based on density gradient?

Brecht Van Lommel brechtvanlommel at pandora.be
Fri Apr 4 11:55:25 CEST 2014

Volume scattering functions don't use normals, so I guess you want to get
surface BSDFs working for volumes, which then need a normal?

Computing the gradient would make the material evaluation maybe 4x slower,
comparing to a volume scatter material, due to evaluating the texture at 4
points. The overall render time impact may not be that bad in practice

On Apr 4, 2014 12:25 AM, "Tiago Estill de Noronha" <
TiagoTiagoT+Bf-funboard at gmail.com> wrote:
> How big would the impact in the performance be if the normals for
> volumetric materials were calculated based on the density gradient (i
> sampling N points around the point in question to see which direction is
> denser; averaging the directions in case there was disagreement)?
> And for homogenous density regions perhaps it could do something like
> produce a <0,0,0> normal internally that gets treated as a sorta wildcard,
> pointing back at the direction of incoming rays?
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