Biomes are used to cover a specific region of a terrain style and type (including filters, materials and objects). So the question is: How is such a region set up?

The answer is Biome Layers. World Creator allows you to create a list of biome layers that are associated with a particular biome. A biome layer is usually drawn by hand using World Creator's paint tools.

Each new World Creator project starts with an initial default biome that has no filters, materials or objects applied to it. There is also no biome layer explicitly set for this biome, which means that World Creator assumes that biomes are globally set for the entire terrain.

But when building more complex terrains and worlds, a single biome is often not enough. Think of mountains and grasslands covering a larger area, or dunes and larger rocks in combination, or even an oasis in a desert. World Creator offers a number of ways to achieve this, but the most effective way is to use biome layers. Here is how they work.

First, create a new project and add a new biome. For simplicity's sake, we will not add any filters, just single-coloured materials so that you can see the boundaries of each biome. Set the color to different values for each of the two biomes. As you can see, the top biome in the biomes list overwrites the one below it, as shown in the image below.

Next, create two Biome Layers by pressing the Plus icon twice, next to the Biome Layers element. Alternatively, you may also press the Create Biome Layer icon next to the Biome name (right to it):

You may check the image below to see the changes.

Biome layers are nothing more than masks. World Creator lets you translate, scale and rotate a mask. To scale, click and drag one of the four corners (small spheres). To translate (move) a mask, simply click inside the mask area and drag in the viewport. To rotate a mask, click and drag outside the mask.

Let's take a closer look at the biome layer settings, which look like this:

The very first element is the Biome selection element. Here you can choose which biome you want to bind the selected biome layer to.

Show Mask lets you toggle the mask visualization, and Mask Visibility lets you adjust the overall visibility. These two are helpful as sometimes the default mask color can be a little distracting.

Next are the area settings. An area defines the boundaries of the terrain and internally covers the biome layer mask, which has a fixed resolution for performance reasons. However, an area can have any size and dimension, which means that the larger the area, the more stretched the mask becomes (more pixelation for larger areas). However, if you are creating large terrains, you can add more and more biome layers assigned to the same biome, giving you the freedom to create high-resolution masks.

The more important area settings are Blend Size and Blend Roundness, which are used to perform blending operations on the underlying biome layers and colours.

The Fit to Terrain button allows you to fit the area size precisely to the terrain size - useful in some cases.

Now you need to assign the biomes to the correct biome layers. You can do this by selecting the mask and selecting the biome by name from the Biome drop-down box. If you then move the top biome layer mask a little to the right of the terrain and deselect it (click somewhere else in the hierarchy), you should see the two biomes as shown below.

Each biome layer is actually just a mask that can be edited directly in World Creator. Editing means that you can draw and paint on it just like in other drawing tools. To do this, select the biome layer you want to edit and click the EDIT button. While in edit mode, you can access all paint operations and brushes by right-clicking in the viewport.

That way you can edit biome layers and mask out or mask in those areas on the terrain you would like the assigned biome to appear or disappear.

 Next: Understanding World Creator's Level Step System