Biome Mask

Setting up a Biome Mask.

Let's get to the point!

A biome mask is a texture that is projected onto the landscape to modify the look of the environment (most often, the grass color).

This image specifically is from, I believe, Chapter 3 Season 3. You might even be able to identify what biomes are being represented. The bottom left corner is what sets the GRASS COLOR, and the top right corner is what sets other layers' colors. As for the bottom right and top left, these are NOT used in the final version of the landscape material shared here.

Now let me go over the colors in the image, for the bottom left (GRASS COLORS) the purple is for the Desert biome, the orange is for the Autumn biome, the brown is for the Sanctuary biome, and the dark teal is for the Taiga biome.

You might be confused as to why purple turns into the desert grass, which is brown-ish: simplifying, this happens because by default the grass color is determined by multiplying the color green by the colors in the biome mask, which unfortunately limits the palette of colors we can use... but, fortunately, there's a setting inside your material instance to make the base grass color be grayscale! This way the grass gets its color DIRECTLY from the biome mask.

As for the top right, notice how it's only 3 pure colors? Red, Green and Blue, these colors are used as masks depending on what region they're supposed to be. For example, the biome mask uses the color red to represent the Taiga biome, and this is used to make the gravel slightly darker.

Setting up YOUR Biome Mask.

I hope you read that big chunk of text above as you'll probably feel way more secure about what you're doing with biome masks for this next part. Once you've painted the colors you want to use in your biome mask texture (PLEASE REFER TO THE PSD FILE INCLUDED INSIDE THE .ZIP FOR THE LANDSCAPE) you will want to actually apply it!

Now this might look a bit intimidating at first, so let me go over these:

The switch "BiomeColors-UseDefault" enables and disables the biome mask, so obviously we want it enabled for this!

The "BiomeTexture" is where you'll input your biome mask texture. Make sure your texture asset has the following settings inside it:
"Texture Group = RVTSourceSpecularMap", "Compression Settings = VectorDisplacementMap (RGBA8)".

The vector "LandscapeWorldUV" is what we're gonna use to line up our biome mask. Let's break it down:
LWUV-X (stands for "LandscapeWorldUV in the X axis"): The pivot point in the X axis from which we project the texture.
LWUV-Y (stands for "LandscapeWorldUV in the Y axis"): The pivot point in the Y axis from which we project the texture.

LWUV-Subtract: Value used to offset the position of the pivot point from which we project the biome texture.
LWUV-Divide: Value used to change the size of the projected texture.

Alright then, let's first input our pivot point position, you might have to mess with this a little yourself, but I'm using my landscape parent actor's pivot point as reference, get the first value (the "Left" or "-Y" axis) and use it for the biome mask.

Now let's set our texture's offset and size. For now let's set the offset to 0 (LWUV-Subtract), and as for the texture size (LWUV-Divide) let's do a some math since we know we just want it to cover the entire landscape. Doing "(OverallLandscapeResolution - 1) * LandscapeActorScale" should work!

It worked...! Or it didn't.

In my case I got it first try! But if your landscape isn't a perfect square you might stumble into some issues, and there I can't really help you as this mask was made... well... with a square landscape in mind. Just add a few landscape proxies and try again!

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