Biome materials vs base materials

APLM ships two layer families that look similar in the Material Instance but behave very differently at runtime: base materials and biome materials. Knowing which family you are working with decides where a parameter lives, what controls it, and whether it responds to seasons.

Base materials

Six base layers are used during automatic landscape generation: MF_BaseBeach, MF_BaseCliff, MF_BaseGrass, MF_BaseGravel, MF_BaseMud, MF_BaseSnow.

• They apply automatically based on landscape geometry (angle, height, normal).
• They react to weather through MPC_Weathers or BP_APLMController.
• They are not bound to MPC_Seasons out of the box. Their per-surface color correction parameters cover the seasonal use case.
• Cliff and Gravel cannot be removed by painting. They are load-bearing for landscape readability.

If you want a base layer to follow a seasonal cycle, add the variables you need to MPC_Seasons yourself and consume them inside the base material. The pattern is shown in the Season system concept page.

Biome materials

Twelve biome layers, nine built-in plus three customizable: MF_BiomeTundra, MF_BiomeBorealForest, MF_BiomeDesert, MF_BiomeMediterranean, MF_BiomeSavanna, MF_BiomeTemperateForest, MF_BiomeTropicalRainforest, MF_BiomeWetland, MF_BiomeGrassland, plus MF_BiomeCustom1, MF_BiomeCustom2, MF_BiomeCustom3.

• They are not applied automatically. You paint them onto the landscape (or use the Auto layer to drive the choice).
• They react to weather through MPC_Weathers or BP_APLMController.
• They are bound to MPC_Seasons, so each biome can shift color, brightness, contrast, specular, and roughness across the seasons.
• Each biome was tuned for the texture model it ships with. Some use a single texture, some blend a primary and a secondary surface (gravel, mud, or grass).
• A seasonal cycle is authored as a Data Asset and applied through Blueprint or Sequencer. The Data Asset is the unit you swap to change a biome’s seasonal behavior.

Tip

When you change a parameter and it does not seem to do anything, double-check whether you are editing the base layer’s category or the biome layer’s category in the Material Instance. They have similar names but separate values.

Picking the right family

Goal	Use
Cliffs apply to steep slopes automatically	Base (Cliff)
Snow above a Z threshold	Base (Snow)
Beach at low Z	Base (Beach)
Painted forest floor with seasonal color	Biome (Temperate Forest)
Painted dune surface, no seasonal change needed	Biome (Desert)
Custom volcanic or alien surface	Biome (Custom1/2/3)
Same surface reacts to rain across the whole landscape	Either family, controlled per layer through MPC_Weathers
Same surface shifts color through the year	Biome family with MPC_Seasons

Where to next

• Available biomes: every shipped biome with its texture model and unique parameters
• Season system: how MPC_Seasons drives per-biome color
• Weather system: how MPC_Weathers drives per-material rain and snow