DerpCraft - Building a MineCraft Clone in Unity - Chunks | Full code available at https://git.io/vrlT3

AirBlock.cs

using Utilities;

public class AirBlock : Block {

  static Block instance;

  public static Block Instance {
    get {
      if (instance == null) {
        instance = new AirBlock();
      }

      return instance;
    }
  }

  AirBlock() {
  }

  protected override bool IsSolid() {
    return false;
  }

  public override MeshData GetBlockData(Chunk chunk, Vector3Int position,
                                        MeshData collectedMeshData) {
    return collectedMeshData;
  }
}

Block-no-sidefix.cs

using UnityEngine;
using Utilities;

public class Block {

  // Enumerator representing the face of the block.
  public enum FaceDirection {
    North,
    // +z
    South,
    // -z
    East,
    // +x
    West,
    // -x
    Top,
    // +y
    Bottom
    // -y
  }

  // Target texture is 16x16 of 16x16 textures.
  static readonly float tileSize = 0.0625f;

  protected virtual Vector2Int TextureTilePosition(Chunk chunk,
                                                   FaceDirection direction) {
    // Default is a hot pink box.
    return new Vector2Int(0, 1);
  }

  protected virtual bool IsSolid() {
    return true;
  }

  // Calculates the UVs for a given direction on the block.
  protected virtual Vector2[] FaceUVs(Chunk chunk, FaceDirection direction) {
    Vector2Int texTile = TextureTilePosition(chunk, direction);

    var uvs = new Vector2[4];
    // top-left, top-right, bottom-right, bottom-left
    uvs[0] = texTile * tileSize + Vector2.up * tileSize;
    uvs[1] = texTile * tileSize + Vector2.one * tileSize;
    uvs[2] = texTile * tileSize + Vector2.right * tileSize;
    uvs[3] = texTile * tileSize;

    return uvs;
  }

  public virtual MeshData GetBlockData(Chunk chunk, Vector3Int position,
                                       MeshData collectedMeshData) {
    // Go through each face and get the vertices, indices, normals, and UVs.
    if (!chunk[position + Vector3Int.up].IsSolid())
      collectedMeshData = FaceDataTop(chunk, position, collectedMeshData);

    if (!chunk[position + Vector3Int.down].IsSolid())
      collectedMeshData = FaceDataBottom(chunk, position, collectedMeshData);

    if (!chunk[position + Vector3Int.north].IsSolid())
      collectedMeshData = FaceDataNorth(chunk, position, collectedMeshData);

    if (!chunk[position + Vector3Int.south].IsSolid())
      collectedMeshData = FaceDataSouth(chunk, position, collectedMeshData);

    if (!chunk[position + Vector3Int.east].IsSolid())
      collectedMeshData = FaceDataEast(chunk, position, collectedMeshData);

    if (!chunk[position + Vector3Int.west].IsSolid())
      collectedMeshData = FaceDataWest(chunk, position, collectedMeshData);

    return collectedMeshData;
  }

  protected virtual MeshData FaceDataTop(Chunk chunk, Vector3Int position,
                                         MeshData collectedMeshData) {
    // top-left, top-right, bottom-right, bottom-left
    collectedMeshData.AddVertex(new Vector3(
      position.x - 0.5f, position.y + 0.5f, position.z + 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x + 0.5f, position.y + 0.5f, position.z + 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x + 0.5f, position.y + 0.5f, position.z - 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x - 0.5f, position.y + 0.5f, position.z - 0.5f));
    // Add tris from verts.
    collectedMeshData.AddQuadTriangles();
    // Add UVs for face.
    collectedMeshData.uvs.AddRange(FaceUVs(chunk, FaceDirection.Top));

    return collectedMeshData;
  }

  protected virtual MeshData FaceDataBottom(Chunk chunk, Vector3Int position,
                                            MeshData collectedMeshData) {
    // top-left, top-right, bottom-right, bottom-left
    collectedMeshData.AddVertex(new Vector3(
      position.x - 0.5f, position.y - 0.5f, position.z - 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x + 0.5f, position.y - 0.5f, position.z - 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x + 0.5f, position.y - 0.5f, position.z + 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x - 0.5f, position.y - 0.5f, position.z + 0.5f));
    // Add tris from verts.
    collectedMeshData.AddQuadTriangles();
    // Add UVs for face.
    collectedMeshData.uvs.AddRange(FaceUVs(chunk, FaceDirection.Bottom));

    return collectedMeshData;
  }

  protected virtual MeshData FaceDataNorth(Chunk chunk, Vector3Int position,
                                           MeshData collectedMeshData) {
    // top-left, top-right, bottom-right, bottom-left
    collectedMeshData.AddVertex(new Vector3(
      position.x + 0.5f, position.y + 0.5f, position.z + 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x - 0.5f, position.y + 0.5f, position.z + 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x - 0.5f, position.y - 0.5f, position.z + 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x + 0.5f, position.y - 0.5f, position.z + 0.5f));
    // Add tris from verts.
    collectedMeshData.AddQuadTriangles();
    // Add UVs for face.
    collectedMeshData.uvs.AddRange(FaceUVs(chunk, FaceDirection.North));

    return collectedMeshData;
  }

  protected virtual MeshData FaceDataSouth(Chunk chunk, Vector3Int position,
                                           MeshData collectedMeshData) {
    // top-left, top-right, bottom-right, bottom-left
    collectedMeshData.AddVertex(new Vector3(
      position.x - 0.5f, position.y + 0.5f, position.z - 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x + 0.5f, position.y + 0.5f, position.z - 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x + 0.5f, position.y - 0.5f, position.z - 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x - 0.5f, position.y - 0.5f, position.z - 0.5f));
    // Add tris from verts.
    collectedMeshData.AddQuadTriangles();
    // Add UVs for face.
    collectedMeshData.uvs.AddRange(FaceUVs(chunk, FaceDirection.South));

    return collectedMeshData;
  }

  protected virtual MeshData FaceDataEast(Chunk chunk, Vector3Int position,
                                          MeshData collectedMeshData) {
    // top-left, top-right, bottom-right, bottom-left
    collectedMeshData.AddVertex(new Vector3(
      position.x + 0.5f, position.y + 0.5f, position.z - 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x + 0.5f, position.y + 0.5f, position.z + 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x + 0.5f, position.y - 0.5f, position.z + 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x + 0.5f, position.y - 0.5f, position.z - 0.5f));
    // Add tris from verts.
    collectedMeshData.AddQuadTriangles();
    // Add UVs for face.
    collectedMeshData.uvs.AddRange(FaceUVs(chunk, FaceDirection.East));

    return collectedMeshData;
  }

  protected virtual MeshData FaceDataWest(Chunk chunk, Vector3Int position,
                                          MeshData collectedMeshData) {
    // top-left, top-right, bottom-right, bottom-left
    collectedMeshData.AddVertex(new Vector3(
      position.x - 0.5f, position.y + 0.5f, position.z + 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x - 0.5f, position.y + 0.5f, position.z - 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x - 0.5f, position.y - 0.5f, position.z - 0.5f));
    collectedMeshData.AddVertex(new Vector3(
      position.x - 0.5f, position.y - 0.5f, position.z + 0.5f));
    // Add tris from verts.
    collectedMeshData.AddQuadTriangles();
    // Add UVs for face.
    collectedMeshData.uvs.AddRange(FaceUVs(chunk, FaceDirection.West));

    return collectedMeshData;
  }

}

Chunk-AirBlocks.cs

using UnityEngine;
using Utilities;

[RequireComponent(typeof(MeshFilter))]
[RequireComponent(typeof(MeshRenderer))]
[RequireComponent(typeof(MeshCollider))]

public class Chunk : MonoBehaviour {

  public static int Size = 16;
  public static int Height = 32;

  Block[,,] blocks = new Block[Size, Height, Size];

  public Block this[int x, int y, int z] {
    get {
      if (x < 0 || x >= Size || y < 0 || y >= Height || z < 0 || z >= Size) {
        return AirBlock.Instance;
      }

      return blocks[x, y, z];
    }

    set {
      if (x < 0 || x >= Size || y < 0 || y >= Height || z < 0 || z >= Size) {
        return;
      }

      blocks[x, y, z] = value;
    }
  }

  public Block this[Vector3Int v] {
    get {
      return this[v.x, v.y, v.z];
    }

    set {
      this[v.x, v.y, v.z] = value;
    }
  }

  void Start() {
    var meshData = new MeshData();

    for (int x = 0; x < Size; x++) {
      for (int y = 0; y < Height; y++) {
        for (int z = 0; z < Size; z++) {
          float rand = Random.value;
          blocks[x, y, z] = rand > 0.5 ? AirBlock.Instance : new GrassBlock();
        }
      }
    }

    for (int x = 0; x < Size; x++) {
      for (int y = 0; y < Height; y++) {
        for (int z = 0; z < Size; z++) {
          meshData = blocks[x, y, z].GetBlockData(
            this, new Vector3Int(x, y, z), meshData);
        }
      }
    }

    meshData.RecalculateNormals();

    // Set the mesh in the MeshFilter for display.
    var filter = GetComponent<MeshFilter>();
    filter.mesh.vertices = meshData.verts.ToArray();
    filter.mesh.triangles = meshData.tris.ToArray();
    filter.mesh.normals = meshData.normals.ToArray();
    filter.mesh.uv = meshData.uvs.ToArray();

    // Set the mesh in the MeshCollider for collision.
    var coll = GetComponent<MeshCollider>();
    var collMesh = new Mesh();
    collMesh.vertices = meshData.colliderVerts.ToArray();
    collMesh.triangles = meshData.colliderTris.ToArray();
    collMesh.normals = meshData.colliderNormals.ToArray();
    coll.sharedMesh = collMesh;

    transform.position = transform.position +
    Vector3.one * 0.5f - new Vector3(Size / 2, 0, Size / 2);
  }
}

Chunk-no-AirBlocks.cs

using UnityEngine;
using Utilities;

[RequireComponent(typeof(MeshFilter))]
[RequireComponent(typeof(MeshRenderer))]
[RequireComponent(typeof(MeshCollider))]

public class Chunk : MonoBehaviour {

  public static int Size = 16;
  public static int Height = 32;

  Block[,,] blocks = new Block[Size, Height, Size];

  class NullBlock : Block {
    static Block instance;

    public static Block Instance {
      get {
        if (instance == null) {
          instance = new NullBlock();
        }

        return instance;
      }
    }

    protected override bool IsSolid() {
      return false;
    }
  }

  public Block this[int x, int y, int z] {
    get {
      if (x < 0 || x >= Size || y < 0 || y >= Height || z < 0 || z >= Size) {
        return NullBlock.Instance;
      }

      return blocks[x, y, z];
    }

    set {
      if (x < 0 || x >= Size || y < 0 || y >= Height || z < 0 || z >= Size) {
        return;
      }

      blocks[x, y, z] = value;
    }
  }

  public Block this[Vector3Int v] {
    get {
      return this[v.x, v.y, v.z];
    }

    set {
      this[v.x, v.y, v.z] = value;
    }
  }

  void Start() {
    var meshData = new MeshData();

    for (int x = 0; x < Size; x++) {
      for (int y = 0; y < Height; y++) {
        for (int z = 0; z < Size; z++) {
          blocks[x, y, z] = new GrassBlock();
        }
      }
    }

    for (int x = 0; x < Size; x++) {
      for (int y = 0; y < Height; y++) {
        for (int z = 0; z < Size; z++) {
          meshData = blocks[x, y, z].GetBlockData(
            this, new Vector3Int(x, y, z), meshData);
        }
      }
    }

    meshData.RecalculateNormals();

    // Set the mesh in the MeshFilter for display.
    var filter = GetComponent<MeshFilter>();
    filter.mesh.vertices = meshData.verts.ToArray();
    filter.mesh.triangles = meshData.tris.ToArray();
    filter.mesh.normals = meshData.normals.ToArray();
    filter.mesh.uv = meshData.uvs.ToArray();

    // Set the mesh in the MeshCollider for collision.
    var coll = GetComponent<MeshCollider>();
    var collMesh = new Mesh();
    collMesh.vertices = meshData.colliderVerts.ToArray();
    collMesh.triangles = meshData.colliderTris.ToArray();
    collMesh.normals = meshData.colliderNormals.ToArray();
    coll.sharedMesh = collMesh;

    transform.position = transform.position +
    Vector3.one * 0.5f - new Vector3(Size / 2, 0, Size / 2);
  }
}