Rune wrote:

> Pigment doesn't require a pattern and a map. In fact it's very common to
> specify just a plain colour.

The plain color case is an exception in the syntax.  It's not very
annoying, but there might be a better way to do it.

> Normal doesn't require a pattern and a map either. The default is a plain
> normal (which is usually achieved by simply not specifying the normal).

No. A "plain normal" can't exist, as a normal is a variation !
(that's also why it doesn't work well with non-gradient patterns, such
as checker).

> >  Of course, "finish" could get some "finish_map", but since, anyway,
> > a pattern isn't *required*, it's still incoherent with "pigment" and
> > "normal".
> 
> I disagree. Pigment and normal doesn't require a pattern - on the other
> hand, if finish_map was implemented, pigment, normal, and finish would
> indeed be very coherent.

 No.  Pigment and normal values rely on the position of the texture's
point in space, while finish rely on the normal value, light positions
and other objects positions.  Put otherwise, pigment and normal are
"global" properties (doesn't change with the point of view), while
finish 
is a "local" (change with the point of view) property.  They do not
belong to the same hierarchy level.
 A proof of that ?  With MegaPOV, you can obtain the value of a pigment
at some point with "eval_pigment", but there's absolutely no way to
get the finish value of a point in space.

> I think finish_map should be implemented.

Yes.  That's the thing that got me thinking about that hierarchy
problem.
I would like to know WHY it hasn't been implemented yet.  I suspect
that the answer would come back to the hierarchy problem.

> I don't have any really good arguments against separating finish from
> pigment and normal; I just think it's unnecessary and that a new group is
> redundant. Instead I would like to see some really good argument *for* the
> separation, because I haven't seen any yet IMHO.

See the global vs. local issue, above.

> What I've written here are only my own thoughts (of course). I would like a
> good discussion!

That's why we're here :-)

Fabien.

Post a reply to this message