gaemstone/src/gaemstone.Bloxel/Systems/BasicWorldGenerator.cs

using System;
using gaemstone.ECS;
using static gaemstone.Bloxel.Components.CoreComponents;
using static gaemstone.Bloxel.Constants;

namespace gaemstone.Bloxel.Systems;

[Module]
[DependsOn<gaemstone.Bloxel.Components.CoreComponents>]
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, EntityRef entity,
		in Chunk chunk, ChunkStoreBlocks blocks,
		[Not] HasBasicWorldGeneration _)
	{
		var stone = universe.LookupOrThrow("Stone");
		for (var lx = 0; lx < ChunkLength; lx++)
			for (var ly = 0; ly < ChunkLength; ly++)
				for (var lz = 0; lz < ChunkLength; lz++) {
					var gx = chunk.Position.X << ChunkBitShift | lx;
					var gy = chunk.Position.Y << ChunkBitShift | ly;
					var gz = chunk.Position.Z << ChunkBitShift | lz;
					var bias = Math.Clamp(gy / 32.0f + 1.0f, 0.0f, 1.0f);
					if (_noise.GetNoise(gx, gy, gz) > bias)
						blocks[lx, ly, lz] = stone;
				}
		entity.Add<HasBasicWorldGeneration>();
	}
}