RobynsVeil opened this issue on Jan 24, 2009 · 490 posts
bagginsbill posted Sun, 25 January 2009 at 6:38 PM
*Your wood grain illustration is mouth-watering, Bill. Second-year, stuff, but definitely mouth-watering. So, I look at those nodes and suddenly realize I'm looking at the result of something that was worked out as a math equation before-hand. The maths actually comes first: the nodes create themselves (virtually) based on the math.
Am I getting any closer?
*Totally.
I made a simple assumption. What makes wood look like wood is not the color itself, but relationship between the colors, and the patterns they form. So if I can capture the essential relationship between the colors, then reproduce that relationship, but change the base color, I'll still retain the look of the wood.
And so that's what I set about doing. There are many mathematical operators. Any of these can be used to describe relationships. Choosing which to use is sometimes a matter of understanding the physics, and sometimes it is just guesswork.
In this case (changing wood color) I took a guess. It works. Is it physics based? Not at all. This is an artistic hackery because it works, not because it is right.
When we think about relationships between different numbers, I like to start with basics.
Fundamentally, there is addition and subtraction (two sides of the same coin).
So, a useful relationship between "a" and "b" can be "a - b". I can then apply that same relationship to some other quantity by addition, i.e. "(a - b) + c". This says, mathematically, compute the additive relationship from a to b, then calculate an equivalent relationship from c. We might call this a mathematical "analogy".
Another possibility is "a / b". So building an analogy from this would simply require "a / b * c".
There are tons of these floating around in the world. I collect them the way you collect samples of anything. Then I use them.
Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)