[Bf-committers] Wood texture update

[Chris Burt]

By popular demand, a comparison:

http://blender.spaceisbig.com/old_wood01.jpg  -  Official 2.36
http://blender.spaceisbig.com/new_wood01.jpg  -  My Build

*Identical* blend file. Blend file created in 2.36 *then* opened in my 
build and rendered with *no* tweaking. Not fantastic, but also only 
represents about 3 minutes of work.

Let the critics decide?

Regards,
--Chris "Trying to sell wood to the masses" Burt

Chris Burt wrote:
> I've been doing some work on the wood texture to find some pleasing 
> results. The previous implementation relied on a periodic function to 
> produce the output values of the wood texture. The end result of this 
> implementation were unavoidable symmetrical intensity bands. The problem 
> with this approach is that trees do not have a sinusoidal growth 
> pattern. They grow faster in one season than another,except for in 
> climates where growth is supported year-round. Thus a quick glance at 
> the grain of any piece of wood generally reveals sharp contrasts between 
> the end of one season of growth and the beginning of another. While you 
> might attempt to reproduce this effect with colorbands, you would fail 
> miserably because no matter how hard you try, the intensities returned 
> by the current wood texture code would only let you control the 
> appearance of 6 months of the year, the latter 6 months being a mirror 
> image of the first. This is illustrated here:
> 
> http://blender.spaceisbig.com/old_colorband_wood.jpg
> 
> In this image you see the colorband, which, given any piece of wood, 
> should represent one year of growth. The yellow color marker represents 
> the month of June, and the red color marker represents the month of 
> December. (Note: These are just examples for simplification. From an 
> artistic standpoint it doesn't really matter what "month" the cursor is 
> in, only that the entire color band represents one year of time)
> 
> http://blender.spaceisbig.com/old_wood.jpg
> 
> In this image you see the resulting wood texture as rendered on a plane 
> in Blender 2.36. It is easy to see in this image that the month of 
> December actually falls where June should fall, and that the last 6 
> months of the "year" are simply a mirror image of the first half of the 
> year. The results aren't nearly as realistic in my opinion. However, 
> when you have proper control over the entire "year" you get results more 
> like this (the result of some quick fiddling before lunch):
> 
> http://blender.spaceisbig.com/new_wood.jpg
> 
> I hope that you all agree this is a more realistic looking texture. I 
> know I haven't created a side-by-side comparison but I hope you can see 
> the usefulness has been improved.
> 
> The good thing about this new implementation is that the intensity 
> values can be made to look like the old system simply by putting the 
> same color marker at each end of the color band. The result is nearly 
> identical.
> 
> Some questions for discussion:
> 
> 1) Are the normals created by my technique accurate? (Probably not).
> 
> 2) How should this be implemented in the UI? Right now I think it would 
> be best if there were a way to use the old method as well, as my method 
> is certainly slower.
> 
> 3) Is there another way to achieve the same result without resorting to 
> using the modulus function I've adapted from "Texturing & Modeling; A 
> procedural approach"? It requires a sawtooth output in order for the 
> user to have complete control (in my opinion.)
> 
> 4) Should the "ring" versions have 3 dimensional components? Trees are 
> cylinders, not spheres.. thus the code creating the output shouldn't be 
> producing spherical rings in my opinion. I had trouble creating 
> realistic results by simple disabling the Z-mapping. Maybe someone has a 
> better idea for this?
> 
> 5) Is this email too long to bother reading? ;)
> 
> Thanks everyone for your input! (Those of you who give any ;)
> 
> Regards,
> --Chris
> 
> 
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