"And" <49341109@ntnu.edu.tw> wrote:

> Thanks. I'm trying to generate small speckles.
>
> It is an emphasis, too.
>
> And I'm thinking how composite this to the base color. I use "average" in this
> picture. But this method is fail to more requirements. Sometimes speckles should
> darker than the base color. the method cannot control it well.

I think that this is going to be another advanced-granite texture odyssey.

You will probably need to use functions, and some way to introduce noise, in
order to randomize those color variations in the growth rings.

If you're going to tackle that, I'd probably start by making a list of common
features of real wood, and think about how to implement each of those, and where
they need to be in a hierarchy.

Different growth ring thicknesses. (one ring vs another)
Variable growth ring thickness (change in thickness along any given ring)
Asymmetric growth ring thickness. (a bent or curved branch will be thick on one
side and thin on the other)
Alternating light-dark / thick-thin growth rings
Darkening along a localized group of rings due to mold/fungus, etc.
Holes due to boring insects
"checking" (cracks) due to splitting when cut wood is rapidly dried
a more granular texture for the rings to represent the fibrous nature of the
wood.
SSLT

Diagrams or photos of wood would likely help you envision the types of functions
that would control each of those attributes, and suggest ways to combine them
into a final overall texture/material.
There are all of the different ways to cut wood to get different grain patterns
and expansion/contraction behaviour.

Then there's the fun of formulating pigment/texture maps for all of the
different species...  ;)

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