gaemstone/src/gaemstone.Bloxel/WorldGen/BasicWorldGenerator.cs

using System;
using gaemstone.ECS;
using static flecs_hub.flecs;

namespace gaemstone.Bloxel.WorldGen;

[Module]
public class BasicWorldGenerator
{
	private readonly FastNoiseLite _noise;

	public BasicWorldGenerator()
	{
		_noise = new(new Random().Next());
		_noise.SetNoiseType(FastNoiseLite.NoiseType.OpenSimplex2);
		_noise.SetFractalType(FastNoiseLite.FractalType.Ridged);
		_noise.SetFractalOctaves(4);
		_noise.SetFractalGain(0.6F);
	}

	[Tag]
	public struct HasBasicWorldGeneration {  }

	[System]
	public void Populate(Universe universe, Entity entity,
		in Chunk chunk, ChunkPaletteStorage<ecs_entity_t> storage,
		[Not] HasBasicWorldGeneration _)
	{
		var stone = universe.Lookup("Stone");
		for (var lx = 0; lx < Chunk.LENGTH; lx++)
			for (var ly = 0; ly < Chunk.LENGTH; ly++)
				for (var lz = 0; lz < Chunk.LENGTH; lz++) {
					var gx = chunk.Position.X << Chunk.BIT_SHIFT | lx;
					var gy = chunk.Position.Y << Chunk.BIT_SHIFT | ly;
					var gz = chunk.Position.Z << Chunk.BIT_SHIFT | lz;
					var bias = Math.Clamp(gy / 32.0F + 1.0F, 0.0F, 1.0F);
					if (_noise.GetNoise(gx, gy, gz) > bias)
						storage[lx, ly, lz] = stone;
				}
		entity.Add<HasBasicWorldGeneration>();
	}
}