TerraBlender — a mod for compatible biome addition in Minecraft

TerraBlender — a mod for compatible biome addition in Minecraft

Starting from version 1.18, Minecraft places biomes not by a flat temperature map, but by several climate noise parameters simultaneously. TerraBlender is a library that integrates into this system and allows multiple mods to add their own biomes without interfering with each other. Without it, mods that work with the same parameter space overlap, override other's areas, and leave sharp seams at the borders. The library allocates separate "regions" to each source and merges them into one world so that modded and vanilla zones coexist side by side. The mod itself doesn't show anything in the game — it is installed as a foundation on which biome mods rely.

Why TerraBlender is needed

The new generation system is convenient for vanilla, but inconvenient for mods. Each biome takes up space in a multidimensional climate field, and when two mods try to fit their zones into the exact same coordinates of this field, one wins, and the rest either disappear or generate in the wrong environment. This leads to deserts right next to taigas, jagged shores, and terrain that doesn't match its neighbor.

The library eliminates this fight for space. Instead of all mods writing to a shared parameter space, each gets its own regions with its own weight, and the distribution of these regions across the map is controlled by a separate layer. Thus, a section of the world belongs to one source — a specific mod or vanilla — and within it, biomes are placed exactly as the author intended.

How the region system works

A region is a set of biomes from a single source plus rules on exactly where to place them in the climate field. Each region has a weight: the higher it is relative to others, the more often the region occurs in the world. On top of the vanilla distribution, the library adds a separate layer that divides the map into zones and assigns a region to each zone. Therefore, the border between modded and vanilla territory turns out smooth: first there is a transition strip, and only then does the terrain completely change its character.

This exact mechanism works in all three dimensions. In the Overworld, regions distribute surface biomes; in the Nether, biomes of this dimension; in the End, biomes of the outer islands. Each dimension has its own settings for region size and vanilla zone weight — more about them in the config section.

Surface rules

In addition to biome placement, the library is responsible for surface rules — what blocks cover the ground in each biome (for example, red sand instead of grass or a special rock beneath the surface). Thanks to this, the added biome gets its correct top layer, not the usual grassy one. The way these rules are integrated into generation can be conflicting at times: in heavy modpacks, it can cause a slight performance overhead or occasionally an incorrect surface at the junction with biomes from other mods.

Config

The settings are located in the terrablender.toml file. It has two sections: [general] — for the Overworld and the Nether, and [end] — for the End. The values are of two types: region or biome size (integer; larger means wider contiguous zones, smaller means more frequent alternation) and vanilla zone weight (integer; larger means more vanilla relative to mods, 0 means vanilla zones of this type disappear, leaving only modded ones).

File limitation: it only regulates region sizes and vanilla zone weights. The weight of individual mods is set by each mod itself, and it cannot be changed here.

Section [general]

Section [end]

The End consists of several zones: the central island, the highlands of the outer islands, the midlands, the barren wastelands closer to the edge, and small separate islands. Sizes are set for each zone, weights — for the vanilla variants of each zone. Weights work here by the same rule as in [general]: the number is the proportion of vanilla zones against modded ones, 0 removes the vanilla variant of the corresponding zone.

Conclusion

TerraBlender allows multiple mods to add biomes to a single game so that the terrain remains cohesive and the transitions between areas are smooth, doing so simultaneously in the Overworld, Nether, and End. Through the config, you can shift the balance towards vanilla or mods and change the size of the zones. It makes sense to install the mod in one case — when it is required by another biome mod, and then there is virtually no substitute for it; for modpack creators, it also provides a lever to adjust the ratio of vanilla and modded terrain for their world.