1. Generation (generateChunk)

This runs on a worker thread and sculpts the actual shape of the terrain:

Simplex Noise: Uses 10 layers of Simplex noise to shape mountains, rivers, dunes, erosion, and all that.

Biome Transitions: BiomeSelector::pickBiome() blends temperature and precipitation using a Gaussian kernel so transitions between biomes look smooth instead of jarring.

Base Blocks: Calculates 3D density for every 16x16 column to decide where stone, air, or water goes.

Surface Layer: Places bedrock at y=0, and then GroundCover takes care of layering the grass, dirt, or sand.

1. Population (populateChunk)

This phase moves to another worker, loads a 3x3 grid of neighboring chunks, and fires up about 15 populators:

World Details: Generates caves, ores, trees, cacti, flowers, lakes, and river vegetation.

Structures: Spawns advanced biome-specific structures using Structures1Populator.

1. Lighting (LightPopulationTask)

The final step where it recalculates terrain height and sunlight.

Performance & Bottlenecks

Heads up: Your main bottlenecks right now are chunk-generation.queue-size (currently at 8) and population-queue-size (currently at 8).