How do I apply shaders to objects?

[Tudor]

Newbie here.
I've gone through the GeekAtPlay rock tutorials and I'd like to do something similar that he did to the rock but to a population of rocks... (I want to add lichen)
Is there a very clear example/tutorial of how nodes work out there?
To be honest it is feeling a bit like black magic right now.
Any help would be greatly appreciated.
Regards,
Tudor

[TheBadger]

do you mean the "fake stones" or the rock object?

In terms of objects you have to click on the objects + sign. this will allow you into the shader network of an object (internal or imported) here you can apply textures or plug in shaders for color or displacement into the object. Is this what you mean?

[Tudor]

Thanks!  I should have thought to click the plus but I kept trying to connect the nodes on the main board.
Is there a way to apply max/min on a per object basis within a population?
I'm trying to give all rocks on a hill moss on top but obviously I'd need to apply a local elevation restriction not a global terrain or even the entire population one.
Tudor

[TheBadger]

Populations will be controlled by applying a distribution node to the outside as you were trying before. A distribution node will control for slope and height. It can be applied and then can be further manipulated by applying a fractal to break up the distribution.

A distribution node can be applied to pretty much everything from objects to shaders to functions. It is pretty powerful, but can be limited. For example you cannot directly tell a distribution node to limit by a slope and also tell it to "exclude" some factor. In other words the distribution node will apply evenly through out, within the confines of its parameters.

However, you can limit the area that a distribution node effects by simply adding a simple shape node. IN this case if attached properly, the distribution node will then only happen with-in the area of the SimpShape. And with the SimpShape node like the distribution node, they can be applied to almost anything and used many times each with different settings.

Think in layers. Apply nodes in combinations.

One method when you are getting started is to start with a SimpShape node. So limit anything that happens to a one or two square mile radius. This way, you will not get distracted by an entire planet. So there will only be displacement in the area of the SSS, and everything outside will be flat and default.

[TheBadger]

Oh sorry, I read your post to fast. I see now you are talking about populating on a population.

You cannot populate an object onto a population now. You can populate a single object with a population of another object though.

As far as getting fake stones to look moss covered. First make your stones the way you like them, then when you are coloring them you can make the color look mossy and probably displace those colors to look more 3d up close. I know there are threads on this but I did not search for them now.

In any case you should not populate an object on to a population, even if you could (which you can't) you would be just killing efficiency for what could not possibly be much gain. The exception may be a super close up, but in this case you would probably make each rock an object, and then you could populate those individuals with a moss or fungus object in addition to color and color displacement.

Is that more what you were asking?

[Tudor]

Thanks very much.
Yes that is very helpful.  I'm still smelling a massive learning curve headed my way but this has helped.
cheers

[Dune]

For example you cannot directly tell a distribution node to limit by a slope and also tell it to "exclude" some factor. In other words the distribution node will apply evenly through out, within the confines of its parameters.

I have to expand on this; you can set a slope restriction within the distribution shader (and also a height restriction), and you can add a node to the masking input, thus breaking up the distribution by more parameters.
Also, lichen is so small, you can best apply it procedurally to a population of stones; add the lichen nodes (small patches of color) through a transform shader (set to world space) to the object shader of the rock. You can do that by adding a surface shader between default shader and parts shader, uncheck its color and add the lichen colors (and perhaps tiny displacement) as a child. You can then restrict the distribution by masking that surface shader by a distribution shader with height and slope restrictions, and a fractal if more patchy is needed, preferably also taken through a transform shader set to world space. I hope this makes sense to you.