[Bf-funboard] A needed node.

Knapp magick.crow at gmail.com
Tue Jul 2 12:37:45 CEST 2013

On Tue, Jul 2, 2013 at 11:44 AM, David Jeske <davidj at gmail.com> wrote:
>> > 1) would it be nice to have a "random value" node which is easier to
>> > than the modulo node? (I'm thinking yes...since these magical floating
>> > point divides don't have good mathematical distribution)
>> Yes, a simple random node is what I want.
> I'll look into it. In the meantime, you can get the random numbers you
> by using my method with the existing Math->Modulo node. Plug object.random
> into one input, and put a random "seed" number into the second slot,
> different for each instance of the modulo node. Just like I did in this
> setup..
>> http://www.pasteall.org/pic/54700
> .. or you can use the Perlin noise texture method I explain below...
>> Page 50 to 55 of the osl-languagespec.pdf has a lot of types of output
>> of the noise pattern generation function that would be great to have
>> as built in nodes!
> That's a good place to get ideas, but as far as implementation... OSL does
> not currently run on the GPU.
> Cycles currently has a 2D Perlin Noise Texture Node which runs on the CPU
> and GPU. You can also use this to generate random color values by plugging
> the object-location into the Noise Texture once for each color-channel,
> tweaking some perlin parameters differently for each color channel.
> Here you can see this Perlin Random method alongside my previous Modulo
> method..
>   http://www.pasteall.org/pic/54704
> Other uses of a random number would be ...
>> selecting palette choices,
> This can be done easily today with object.random and a ColorRamp.
>> picking textures from a list
> This sounds interesting. Can you think of some specific examples of using
> this?

The go stones. :-)

Any place you want to use a selection of tiles that don't repeat in an
orderly way.

It was used here. Strange use but looks cool.

> I think this can be done today with a combination of
> Math->GreaterThan/LessThan, and Mix nodes, but it would be a huge mess. I
> can imagine a "Shader Multiplexer" node, where an input factor would
> between different shader inputs. It would be easier to use if it had a
> variable number of inputs. I also wonder if it needs some kind of
> like configuration or not. Hard to guess without a use-case.
> making a random point cloud, vectors for explosions
> I'm confused here. Are you talking about the new particle-nodes stuff?
> Particle systems already have random factors.

I was thinking of all the places I use random in Panda3d programming. You
are correct, it has nothing to do with node textures. I blame my sickness.

>> or other random things, to do small adjustments to just about anything
>> don't want constant, like green color of a tree's leaves. The color of
>> gravel pieces.
> Makes sense. This is possible today in a few different ways, but I see the
> benefit of having an "easy to find and use" multi-seed random node that
> artists can just drop in.

Ya, that was really my first point. There are ways but you have to be
clever to find them and perhaps know a bit of programming or the inner
workings of Blender and its cycles node system. Not something that most
artists will have. It also is just simply messy. With a random node we are
often talking about replacing at least 3 nodes. Easy to use = good design.

Douglas E Knapp

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