Added flat world generator sample

Author: Vyacheslav

VoxelGame_UnityProject/Assets/VoxelGame/Voxel/Scripts/Generators/FlatGenerator.cs

@@ -0,0 +1,161 @@
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace VoxelGame.Voxel
+{
+    public class FlatGenerator : IGenerator
+    {
+        private readonly VoxelSettingsSO voxelSettings;
+
+        public FlatGenerator(VoxelSettingsSO voxelSettings)
+        {
+            this.voxelSettings = voxelSettings;
+        }
+
+        const uint p = 2147483647;
+        const uint a = 16807;
+        
+        private uint Rand(uint current)
+        {
+            current = a * current % p;
+            return current;
+        }
+
+        public void GenerateMap(Vector3Int position, ref byte[,,] map)
+        {
+            if (map == null)
+                return;
+
+            int lengthX = map.GetLength(0);
+            int lengthY = map.GetLength(1);
+            int lengthZ = map.GetLength(2);
+
+            if (lengthX == 0 || lengthY == 0 || lengthZ == 0)
+                return;
+
+            byte[] tmpMapColumn = new byte[lengthY];
+
+            for (int x = 0; x < lengthX; x++)
+                for (int z = 0; z < lengthZ; z++)
+                {
+                    GenerateMapColumn(position + new Vector3Int(x, 0, z), tmpMapColumn);
+
+                    for (int y = 0; y < lengthY; y++)
+                        map[x, y, z] = tmpMapColumn[y];
+                }
+        }
+
+        public void GenerateChunkStructures(Vector2Int coords, ref byte[,,] map)
+        {
+            List<ChunkStructure> structures = new List<ChunkStructure>();
+
+            for (int x = -1; x <= 1; x++)
+                for (int z = -1; z <= 1; z++)
+                    structures.AddRange(GetChunkStructures(coords + new Vector2Int(x, z)));
+
+            ChunkStructure.CreateStructures(coords, map, structures);
+        }
+
+        private void GenerateMapColumn(Vector3Int position, byte[] mapY)
+        {
+            uint rndCurrent = (uint)(voxelSettings.Seed + position.x + position.z * 7 + voxelSettings.Seed * position.x);
+
+            byte lastVoxel = 0;
+            int deep = 0;
+
+            for (int y = mapY.Length - 1; y >= 0; y--)
+            {
+                mapY[y] = GetVoxel(position + new Vector3Int(0, y, 0));
+                deep = mapY[y] > 0 ? deep + 1 : 0;
+                mapY[y] = FixVoxel(mapY[y], deep);
+
+                if (y < mapY.Length - 1)
+                {
+                    rndCurrent = Rand(rndCurrent);
+                    mapY[y + 1] = FixPrevVoxel(mapY[y], lastVoxel, y, (int)(rndCurrent % 50));
+                }
+
+                lastVoxel = mapY[y];
+            }
+        }
+
+        private List<ChunkStructure> GetChunkStructures(Vector2Int coords)
+        {
+            Vector3Int position = VoxelUtils.GetChunkPosition(coords);
+
+            uint rndCurrent = (uint)(position.x + position.z * 7 + voxelSettings.Seed);
+
+            List<ChunkStructure> structures = new List<ChunkStructure>();
+
+            for (int x = 0; x < VoxelData.chunkWidth; x++)
+                for (int z = 0; z < VoxelData.chunkWidth; z++)
+                {
+                    rndCurrent = Rand(rndCurrent);
+
+                    if ((int)(rndCurrent % 400) != 1)
+                        continue;
+
+                    byte[] mapColumn = new byte[VoxelData.chunkHeight];
+                    GenerateMapColumn(position + new Vector3Int(x, 0, z), mapColumn);
+
+                    for (int y = VoxelData.chunkHeight - 1; y >= 0; y--)
+                    {
+                        Vector3Int v = new Vector3Int(x, y, z);
+
+                        if (!VoxelUtils.IsVoxelInChunk(v))
+                            continue;
+
+                        byte voxel = mapColumn[y];
+
+                        if (voxel == Voxels.GRASS)
+                        {
+                            ChunkStructure s = new ChunkStructure();
+                            s.position = new Vector3Int(x, y + 1, z) + position;
+                            s.structure = voxelSettings.Structures.GetStructure("tree_1");
+                            structures.Add(s);
+
+                            break;
+                        }
+                    }
+                }
+
+            return structures;
+        }
+
+        private byte GetVoxel(Vector3Int pos)
+        {
+            return pos.y > VoxelData.chunkHeight / 2 ? Voxels.AIR : Voxels.GRASS;
+        }
+
+        private byte FixVoxel(byte voxel, int deep)
+        {
+            if (voxel == Voxels.GRASS)
+            {
+                if (deep == 1)
+                {
+                    return Voxels.GRASS;
+                }
+                else if (deep < 4)
+                {
+                    return Voxels.DIRT;
+                }
+                else
+                {
+                    return Voxels.STONE;
+                }
+            }
+
+            return voxel;
+        }
+
+        private byte FixPrevVoxel(byte voxel, byte lastVoxel, int y, int rnd100)
+        {
+            if (lastVoxel == 0 && y < VoxelData.chunkHeight - 1)
+                if (voxel == Voxels.GRASS)
+                    if (rnd100 < 5)
+                        return Voxels.DECOR_GRASS;
+
+            return lastVoxel;
+        }
+    }
+}