I liked to combine two different materials in to one material in nodes, so that I could create mountain like structures.
I try to use the noise as the base of the mountain structure, and add a different snow like material to the top of the hills where the normal height is high in the noise texture.
How do I combine two different material on top of each other, so that the height decides what material is used?
For your mountain example, you can use position attribute in geometry input node as a factor for high in Mix Shader or MixRGB (depend on using shader or using texture).
In the other way, you can use weight paint for highlighting the area you want, and then use Layer Weight node as a factor.
There are multiple ways to combine two different materials into one. As well as mixing them together from some controled factor.
To combine, the easies way is to select some nodes and paste them where you want them, using ⎈ CtrlC and ⎈ CtrlV.
But if your materials are quite complex individually, this might just create a result too messy to work with.
So, the second solution would be to create node groups out of your original materials (select all but the material ouptut node and press ⎈ CtrlG, manage thee goup node's inputs and ouptus). Then in a new material, you will be abble to find these nodegroup inside the Add node menu → Group → your node group.
As for mixing shaders, you have the Add Shader and Mix Shader.
