It’s a very broad question imho. “Combining” and “Masking” are two pillars on which terrain design in world machine relies heavily. Answering this question in a specific “workflow” type of manner is beyond my typing ability tbh. This is where an official documentation comes in, though in case of world machine its incomplete at the moment. Bookmark THIS link, the official location for help resources. This is where any future node reference will be hosted.
In general, there are a few nodes that offer different type of combinations in world machine. I’ll list them below.
-
“Combiner” - This is the node that offers photoshop style layer blending. The blending modes are specific to terrain and material color data in world machine though. You can mask the combination effect, but not terrain elements (you can “abuse” it for that purpose, but the next node is more suitable for that).
-
“Chooser” - This node “chooses” between two different terrains, based on a black and white mask. Similar to “alpha blending” or “alpha over” operation in other apps. The mask is called control input here, and is mandatory for the output to function. You can use chooser in a cascading style setup to combine more than two individual heightmap elements.
-
“Layers” - This is a fairly new compositing node used to combine between multiple arbitrary layers. Be it terrains, materials, or other color data. The combination is performed similar to a cascading setup of choosers, but you can flip a layer to be under or over easily within node properties. Currently it’s not stackable like choosers, but may be in the future with an additional feature similar to “arrays”.
-
“Mimic” - This one is explained in THIS blog post.
Now coming back to your specific need @hualiyujusang
The nodes you probably need, are “combiner” and “chooser”. A few things you need to remember while combining terrain heightmaps. -
a) Both terrains need to be similar in “xy scale” in order to match edges. Unless you’re going for asymetrical biome combination, in which case use common sense to calculate scale.
b) “Masking” stuff needs to be a second nature while working in world machine. Will help with your terrain mixing needs too.
c) There are many ways to “use” and “abuse” nodes in world machine. Just go over some introductory stuff at the link below, will help you “think world machine” better if you’re familiar with these fundamental concepts.
https://help.world-machine.com/
Hope this tirade helps!