riversong-code-showcase/Source/Riversong/Game/WorldGen/ChunkGenerators/GrassChunkMeshGenerator.cs

using Unity.Collections;
using Unity.Jobs;
using Unity.Mathematics;
using UnityEngine;
using UnityEngine.Rendering;
using Random = Unity.Mathematics.Random;

namespace DanieleMarotta.RiversongCodeShowcase
{
    public class GrassChunkMeshGenerator : GrassChunkMeshGeneratorBase<GrassTileMask>
    {
        public GrassChunkMeshGenerator(World world, GameConfig config) : base(world, config)
        {
        }

        protected override int GetLodCount()
        {
            return Config.Terrain.GrassLODs.Length;
        }

        protected override string GetGameObjectName(string chunkName, int2 chunkCoords, int lod)
        {
            return $"{chunkName}_Grass_LOD{lod}";
        }

        protected override void InitializeChunk(TerrainChunk chunk, int lod, GameObject gameObject, Mesh mesh, Renderer renderer)
        {
            base.InitializeChunk(chunk, lod, gameObject, mesh, renderer);

            renderer.shadowCastingMode = ShadowCastingMode.Off;

            chunk.GrassLODs[lod] = new TerrainChunk.RenderData(mesh, renderer);
        }

        protected override Mesh GetMesh(TerrainChunk chunk, int lod)
        {
            return chunk.GrassLODs[lod].Mesh;
        }

        protected override JobHandle ScheduleJob(ChunkGenerationJobState jobState, NativeArray<int2> chunkCoords, NativeArray<Random> randomArray)
        {
            var job = new GenerateGrassChunkJob<GrassTileMask>();
            PrepareJob(jobState, chunkCoords, randomArray, jobState.Lod, ref job);
            return job.Schedule(chunkCoords.Length, Config.WorldGen.ChunksPerThread);
        }

        protected override Renderer GetRenderer(TerrainChunk chunk, int lod)
        {
            return chunk.GrassLODs[lod].Renderer;
        }

        protected override Material GetMaterial(int lod)
        {
            return Config.Terrain.GrassMaterial;
        }

        protected override GameConfig.WorldGenConfig.GrassConfig GetGrassGenerationConfig()
        {
            return Config.WorldGen.Grass;
        }

        protected override GrassTileMask GetMask()
        {
            var heightmap = World.Heightmap.GetNativeArray();
            var fertility = World.Fertility.GetNativeArray();
            return new GrassTileMask
            {
                Heightmap = heightmap,
                Fertility = fertility
            };
        }

        protected override int GetDensityForLOD(int lod)
        {
            return Config.Terrain.GrassLODs[lod].Density;
        }
    }
}