This isn't so much a request for indigo, but I'm curious about the possibility of making a wood shader using indigo's shader language that is based on some common characteristics of wood. If you have it lying around, bamboo is probably the most obvious. You can see that
(1) the wood has a cross section consisting of veins, sap deposits and tissue.
(2) The section occurs pependicular to the direction of growth or the outer surface of the plant. At a macroscopic level, alternating light and dark rings can be seen, these "rings" are actually the growth of the tree over a season. Growth early in the season occurs quickly and is charactarized by a higher ratio of large diameter veins, as the season progresses [I'm guessing] the new veins increase the rate at which new tissue can be produced, and the ratio of vein to tissue flips. So
(3) the cross-section is always made up of an "early", porous dark ring and the "late" solid light ring. The transition between light to dark varies from species to species. Bamboo has a very smooth gradient, pine is very sudden. The size of light and dark rings also varies with species and is dependent on climatic conditions and age of the plant
(4) In addition to the rings you also have the medullary rays, which generally radiate out from the center of the cross section and transport sap in that direction.
So, in the cross-section, you have:
1. rings composed of veins
2. rays composed of veins
3. other stuff
When cut perpendicular to the cross-section, the veins appear dark if cut and shiny if grazed, the other stuff is relatively dull.
The rings and rays warp in cross-section as the tree grows in different different directions or branches. All this depends on the species and how the tree grew.
This site is cool:
http://www.woodanatomy.ch/species.php?code=ACPS
Also an explanation of how grains appear in cut wood:
http://www.awi-wa.com/_hidden/veneercut.htm
How hard can it be?
