src/world/chunk.cpp

   1 #include "BlockLookup.hpp"
   2 #include "Chunk.hpp"
   3 #include "ChunkLoader.hpp"
   4
   5 #include "Generator.hpp"
   6 #include "WorldCollision.hpp"
   7 #include "../io/WorldSave.hpp"
   8
   9 #include <algorithm>
  10 #include <limits>
  11 #include <ostream>
  12 #include <queue>
  13
  14
  15 namespace blank {
  16
  17 constexpr int Chunk::width;
  18 constexpr int Chunk::height;
  19 constexpr int Chunk::depth;
  20 constexpr int Chunk::size;
  21
  22
  23 Chunk::Chunk(const BlockTypeRegistry &types) noexcept
  24 : types(&types)
  25 , neighbor{0}
  26 , blocks{}
  27 , light{0}
  28 , position(0, 0, 0)
  29 , dirty_model(false)
  30 , dirty_save(false) {
  31
  32 }
  33
  34 Chunk::Chunk(Chunk &&other) noexcept
  35 : types(other.types)
  36 , position(other.position)
  37 , dirty_model(other.dirty_model)
  38 , dirty_save(other.dirty_save) {
  39         std::copy(other.neighbor, other.neighbor + sizeof(neighbor), neighbor);
  40         std::copy(other.blocks, other.blocks + sizeof(blocks), blocks);
  41         std::copy(other.light, other.light + sizeof(light), light);
  42 }
  43
  44 Chunk &Chunk::operator =(Chunk &&other) noexcept {
  45         types = other.types;
  46         std::copy(other.neighbor, other.neighbor + sizeof(neighbor), neighbor);
  47         std::copy(other.blocks, other.blocks + sizeof(blocks), blocks);
  48         std::copy(other.light, other.light + sizeof(light), light);
  49         position = other.position;
  50         dirty_model = other.dirty_save;
  51         dirty_save = other.dirty_save;
  52         return *this;
  53 }
  54
  55
  56 namespace {
  57
  58 struct SetNode {
  59
  60         Chunk *chunk;
  61         Chunk::Pos pos;
  62
  63         SetNode(Chunk *chunk, Chunk::Pos pos)
  64         : chunk(chunk), pos(pos) { }
  65
  66         int Get() const noexcept { return chunk->GetLight(pos); }
  67         void Set(int level) noexcept { chunk->SetLight(pos, level); }
  68
  69         const BlockType &GetType() const noexcept { return chunk->Type(Chunk::ToIndex(pos)); }
  70
  71         bool HasNext(Block::Face face) noexcept {
  72                 const BlockType &type = GetType();
  73                 if (type.block_light && !type.luminosity) return false;
  74                 const BlockLookup next(chunk, pos, face);
  75                 return next;
  76         }
  77         SetNode GetNext(Block::Face face) noexcept {
  78                 const BlockLookup next(chunk, pos, face);
  79                 return SetNode(&next.GetChunk(), next.GetBlockPos());
  80         }
  81
  82 };
  83
  84 struct UnsetNode
  85 : public SetNode {
  86
  87         int level;
  88
  89         UnsetNode(Chunk *chunk, Chunk::Pos pos)
  90         : SetNode(chunk, pos), level(Get()) { }
  91
  92         UnsetNode(const SetNode &set)
  93         : SetNode(set), level(Get()) { }
  94
  95
  96         bool HasNext(Block::Face face) noexcept {
  97                 const BlockLookup next(chunk, pos, face);
  98                 return next;
  99         }
 100         UnsetNode GetNext(Block::Face face) noexcept { return UnsetNode(SetNode::GetNext(face)); }
 101
 102 };
 103
 104 std::queue<SetNode> light_queue;
 105 std::queue<UnsetNode> dark_queue;
 106
 107 void work_light() noexcept {
 108         while (!light_queue.empty()) {
 109                 SetNode node = light_queue.front();
 110                 light_queue.pop();
 111
 112                 int level = node.Get() - 1;
 113                 for (int face = 0; face < Block::FACE_COUNT; ++face) {
 114                         if (node.HasNext(Block::Face(face))) {
 115                                 SetNode other = node.GetNext(Block::Face(face));
 116                                 if (other.Get() < level) {
 117                                         other.Set(level);
 118                                         light_queue.emplace(other);
 119                                 }
 120                         }
 121                 }
 122         }
 123 }
 124
 125 void work_dark() noexcept {
 126         while (!dark_queue.empty()) {
 127                 UnsetNode node = dark_queue.front();
 128                 dark_queue.pop();
 129
 130                 for (int face = 0; face < Block::FACE_COUNT; ++face) {
 131                         if (node.HasNext(Block::Face(face))) {
 132                                 UnsetNode other = node.GetNext(Block::Face(face));
 133                                 // TODO: if there a light source here with the same level this will err
 134                                 if (other.Get() != 0 && other.Get() < node.level) {
 135                                         other.Set(0);
 136                                         dark_queue.emplace(other);
 137                                 } else {
 138                                         light_queue.emplace(other);
 139                                 }
 140                         }
 141                 }
 142         }
 143 }
 144
 145 }
 146
 147 void Chunk::SetBlock(int index, const Block &block) noexcept {
 148         const BlockType &old_type = Type(blocks[index]);
 149         const BlockType &new_type = Type(block);
 150
 151         blocks[index] = block;
 152         Invalidate();
 153
 154         if (&old_type == &new_type) return;
 155
 156         if (new_type.luminosity > old_type.luminosity) {
 157                 // light added
 158                 SetLight(index, new_type.luminosity);
 159                 light_queue.emplace(this, ToPos(index));
 160                 work_light();
 161         } else if (new_type.luminosity < old_type.luminosity) {
 162                 // light removed
 163                 dark_queue.emplace(this, ToPos(index));
 164                 SetLight(index, 0);
 165                 work_dark();
 166                 SetLight(index, new_type.luminosity);
 167                 light_queue.emplace(this, ToPos(index));
 168                 work_light();
 169         } else if (new_type.block_light && !old_type.block_light) {
 170                 // obstacle added
 171                 if (GetLight(index) > 0) {
 172                         dark_queue.emplace(this, ToPos(index));
 173                         SetLight(index, 0);
 174                         work_dark();
 175                         work_light();
 176                 }
 177         } else if (!new_type.block_light && old_type.block_light) {
 178                 // obstacle removed
 179                 int level = 0;
 180                 Pos pos(ToPos(index));
 181                 for (int face = 0; face < Block::FACE_COUNT; ++face) {
 182                         BlockLookup next_block(this, pos, Block::Face(face));
 183                         if (next_block) {
 184                                 level = std::max(level, next_block.GetLight());
 185                         }
 186                 }
 187                 if (level > 1) {
 188                         SetLight(index, level - 1);
 189                         light_queue.emplace(this, pos);
 190                         work_light();
 191                 }
 192         }
 193 }
 194
 195 namespace {
 196
 197 // propagate light from a's edge to b
 198 void edge_light(
 199         Chunk &a, const Chunk::Pos &a_pos,
 200         Chunk &b, const Chunk::Pos &b_pos
 201 ) noexcept {
 202         if (a.GetLight(a_pos) > 1) {
 203                 const BlockType &b_type = b.Type(Chunk::ToIndex(b_pos));
 204                 if (!b_type.block_light) {
 205                         light_queue.emplace(&a, a_pos);
 206                 }
 207                 if (b_type.visible) {
 208                         b.Invalidate();
 209                 }
 210         }
 211 }
 212
 213 }
 214
 215 void Chunk::SetNeighbor(Chunk &other) noexcept {
 216         if (other.position == position + Pos(-1, 0, 0)) {
 217                 if (neighbor[Block::FACE_LEFT] != &other) {
 218                         neighbor[Block::FACE_LEFT] = &other;
 219                         other.neighbor[Block::FACE_RIGHT] = this;
 220                         for (int z = 0; z < depth; ++z) {
 221                                 for (int y = 0; y < height; ++y) {
 222                                         Pos my_pos(0, y, z);
 223                                         Pos other_pos(width - 1, y, z);
 224                                         edge_light(*this, my_pos, other, other_pos);
 225                                         edge_light(other, other_pos, *this, my_pos);
 226                                 }
 227                         }
 228                         work_light();
 229                 }
 230         } else if (other.position == position + Pos(1, 0, 0)) {
 231                 if (neighbor[Block::FACE_RIGHT] != &other) {
 232                         neighbor[Block::FACE_RIGHT] = &other;
 233                         other.neighbor[Block::FACE_LEFT] = this;
 234                         for (int z = 0; z < depth; ++z) {
 235                                 for (int y = 0; y < height; ++y) {
 236                                         Pos my_pos(width - 1, y, z);
 237                                         Pos other_pos(0, y, z);
 238                                         edge_light(*this, my_pos, other, other_pos);
 239                                         edge_light(other, other_pos, *this, my_pos);
 240                                 }
 241                         }
 242                         work_light();
 243                 }
 244         } else if (other.position == position + Pos(0, -1, 0)) {
 245                 if (neighbor[Block::FACE_DOWN] != &other) {
 246                         neighbor[Block::FACE_DOWN] = &other;
 247                         other.neighbor[Block::FACE_UP] = this;
 248                         for (int z = 0; z < depth; ++z) {
 249                                 for (int x = 0; x < width; ++x) {
 250                                         Pos my_pos(x, 0, z);
 251                                         Pos other_pos(x, height - 1, z);
 252                                         edge_light(*this, my_pos, other, other_pos);
 253                                         edge_light(other, other_pos, *this, my_pos);
 254                                 }
 255                         }
 256                         work_light();
 257                 }
 258         } else if (other.position == position + Pos(0, 1, 0)) {
 259                 if (neighbor[Block::FACE_UP] != &other) {
 260                         neighbor[Block::FACE_UP] = &other;
 261                         other.neighbor[Block::FACE_DOWN] = this;
 262                         for (int z = 0; z < depth; ++z) {
 263                                 for (int x = 0; x < width; ++x) {
 264                                         Pos my_pos(x, height - 1, z);
 265                                         Pos other_pos(x, 0, z);
 266                                         edge_light(*this, my_pos, other, other_pos);
 267                                         edge_light(other, other_pos, *this, my_pos);
 268                                 }
 269                         }
 270                         work_light();
 271                 }
 272         } else if (other.position == position + Pos(0, 0, -1)) {
 273                 if (neighbor[Block::FACE_BACK] != &other) {
 274                         neighbor[Block::FACE_BACK] = &other;
 275                         other.neighbor[Block::FACE_FRONT] = this;
 276                         for (int y = 0; y < height; ++y) {
 277                                 for (int x = 0; x < width; ++x) {
 278                                         Pos my_pos(x, y, 0);
 279                                         Pos other_pos(x, y, depth - 1);
 280                                         edge_light(*this, my_pos, other, other_pos);
 281                                         edge_light(other, other_pos, *this, my_pos);
 282                                 }
 283                         }
 284                         work_light();
 285                 }
 286         } else if (other.position == position + Pos(0, 0, 1)) {
 287                 if (neighbor[Block::FACE_FRONT] != &other) {
 288                         neighbor[Block::FACE_FRONT] = &other;
 289                         other.neighbor[Block::FACE_BACK] = this;
 290                         for (int y = 0; y < height; ++y) {
 291                                 for (int x = 0; x < width; ++x) {
 292                                         Pos my_pos(x, y, depth - 1);
 293                                         Pos other_pos(x, y, 0);
 294                                         edge_light(*this, my_pos, other, other_pos);
 295                                         edge_light(other, other_pos, *this, my_pos);
 296                                 }
 297                         }
 298                         work_light();
 299                 }
 300         }
 301 }
 302
 303 void Chunk::ClearNeighbors() noexcept {
 304         for (int face = 0; face < Block::FACE_COUNT; ++face) {
 305                 if (neighbor[face]) {
 306                         neighbor[face]->neighbor[Block::Opposite(Block::Face(face))] = nullptr;
 307                         neighbor[face] = nullptr;
 308                 }
 309         }
 310 }
 311
 312
 313 void Chunk::SetLight(int index, int level) noexcept {
 314         if (light[index] != level) {
 315                 light[index] = level;
 316                 Invalidate();
 317         }
 318 }
 319
 320 int Chunk::GetLight(int index) const noexcept {
 321         return light[index];
 322 }
 323
 324 float Chunk::GetVertexLight(const Pos &pos, const BlockModel::Position &vtx, const EntityModel::Normal &norm) const noexcept {
 325         int index = ToIndex(pos);
 326         float light = GetLight(index);
 327
 328         Block::Face direct_face(Block::NormalFace(norm));
 329         // tis okay
 330         BlockLookup direct(const_cast<Chunk *>(this), pos, Block::NormalFace(norm));
 331         if (direct) {
 332                 float direct_light = direct.GetLight();
 333                 if (direct_light > light) {
 334                         light = direct_light;
 335                 }
 336         } else {
 337                 return light;
 338         }
 339
 340         if (Type(BlockAt(index)).luminosity > 0 || direct.GetType().block_light) {
 341                 return light;
 342         }
 343
 344         Block::Face edge[2];
 345         switch (Block::Axis(direct_face)) {
 346                 case 0: // X
 347                         edge[0] = (vtx.y - pos.y) > 0.5f ? Block::FACE_UP : Block::FACE_DOWN;
 348                         edge[1] = (vtx.z - pos.z) > 0.5f ? Block::FACE_FRONT : Block::FACE_BACK;
 349                         break;
 350                 case 1: // Y
 351                         edge[0] = (vtx.z - pos.z) > 0.5f ? Block::FACE_FRONT : Block::FACE_BACK;
 352                         edge[1] = (vtx.x - pos.x) > 0.5f ? Block::FACE_RIGHT : Block::FACE_LEFT;
 353                         break;
 354                 case 2: // Z
 355                         edge[0] = (vtx.x - pos.x) > 0.5f ? Block::FACE_RIGHT : Block::FACE_LEFT;
 356                         edge[1] = (vtx.y - pos.y) > 0.5f ? Block::FACE_UP : Block::FACE_DOWN;
 357                         break;
 358         }
 359
 360         int num = 1;
 361         int occlusion = 0;
 362
 363         BlockLookup next[2] = {
 364                 direct.Next(edge[0]),
 365                 direct.Next(edge[1]),
 366         };
 367
 368         if (next[0]) {
 369                 if (next[0].GetType().block_light) {
 370                         ++occlusion;
 371                 } else {
 372                         light += next[0].GetLight();
 373                         ++num;
 374                 }
 375         }
 376         if (next[1]) {
 377                 if (next[1].GetType().block_light) {
 378                         ++occlusion;
 379                 } else {
 380                         light += next[1].GetLight();
 381                         ++num;
 382                 }
 383         }
 384         if (occlusion < 2) {
 385                 if (next[0]) {
 386                         BlockLookup corner = next[0].Next(edge[1]);
 387                         if (corner) {
 388                                 if (corner.GetType().block_light) {
 389                                         ++occlusion;
 390                                 } else {
 391                                         light += corner.GetLight();
 392                                         ++num;
 393                                 }
 394                         }
 395                 } else if (next[1]) {
 396                         BlockLookup corner = next[1].Next(edge[0]);
 397                         if (corner) {
 398                                 if (corner.GetType().block_light) {
 399                                         ++occlusion;
 400                                 } else {
 401                                         light += corner.GetLight();
 402                                         ++num;
 403                                 }
 404                         }
 405                 }
 406         } else {
 407                 ++occlusion;
 408         }
 409
 410         return (light / num) - (occlusion * 0.8f);
 411 }
 412
 413
 414 bool Chunk::IsSurface(const Pos &pos) const noexcept {
 415         const Block &block = BlockAt(pos);
 416         if (!Type(block).visible) {
 417                 return false;
 418         }
 419         for (int face = 0; face < Block::FACE_COUNT; ++face) {
 420                 BlockLookup next = BlockLookup(const_cast<Chunk *>(this), pos, Block::Face(face));
 421                 if (!next || !next.GetType().visible) {
 422                         return true;
 423                 }
 424         }
 425         return false;
 426 }
 427
 428
 429 bool Chunk::Intersection(
 430         const Ray &ray,
 431         const glm::mat4 &M,
 432         WorldCollision &coll
 433 ) noexcept {
 434         int idx = 0;
 435         coll.chunk = this;
 436         coll.block = -1;
 437         coll.depth = std::numeric_limits<float>::infinity();
 438         for (int z = 0; z < depth; ++z) {
 439                 for (int y = 0; y < height; ++y) {
 440                         for (int x = 0; x < width; ++x, ++idx) {
 441                                 const BlockType &type = Type(idx);
 442                                 if (!type.visible) {
 443                                         continue;
 444                                 }
 445                                 float cur_dist;
 446                                 glm::vec3 cur_norm;
 447                                 if (type.shape->Intersects(ray, M * ToTransform(Pos(x, y, z), idx), cur_dist, cur_norm)) {
 448                                         if (cur_dist < coll.depth) {
 449                                                 coll.block = idx;
 450                                                 coll.depth = cur_dist;
 451                                                 coll.normal = cur_norm;
 452                                         }
 453                                 }
 454                         }
 455                 }
 456         }
 457
 458         if (coll.block < 0) {
 459                 return false;
 460         } else {
 461                 coll.normal = glm::vec3(BlockAt(coll.block).Transform() * glm::vec4(coll.normal, 0.0f));
 462                 return true;
 463         }
 464 }
 465
 466 bool Chunk::Intersection(
 467         const AABB &box,
 468         const glm::mat4 &Mbox,
 469         const glm::mat4 &Mchunk,
 470         std::vector<WorldCollision> &col
 471 ) noexcept {
 472         bool any = false;
 473         float penetration;
 474         glm::vec3 normal;
 475
 476         if (!blank::Intersection(box, Mbox, Bounds(), Mchunk, penetration, normal)) {
 477                 return false;
 478         }
 479         for (int idx = 0, z = 0; z < depth; ++z) {
 480                 for (int y = 0; y < height; ++y) {
 481                         for (int x = 0; x < width; ++x, ++idx) {
 482                                 const BlockType &type = Type(idx);
 483                                 if (!type.collision) {
 484                                         continue;
 485                                 }
 486                                 if (type.shape->Intersects(Mchunk * ToTransform(Pos(x, y, z), idx), box, Mbox, penetration, normal)) {
 487                                         col.emplace_back(this, idx, penetration, normal);
 488                                         any = true;
 489                                 }
 490                         }
 491                 }
 492         }
 493         return any;
 494 }
 495
 496
 497 namespace {
 498
 499 BlockModel::Buffer buf;
 500
 501 }
 502
 503 void Chunk::Update(BlockModel &model) noexcept {
 504         int vtx_count = 0, idx_count = 0;
 505         for (const auto &block : blocks) {
 506                 const Shape *shape = Type(block).shape;
 507                 vtx_count += shape->VertexCount();
 508                 idx_count += shape->VertexIndexCount();
 509         }
 510         buf.Clear();
 511         buf.Reserve(vtx_count, idx_count);
 512
 513         int idx = 0;
 514         BlockModel::Index vtx_counter = 0;
 515         for (size_t z = 0; z < depth; ++z) {
 516                 for (size_t y = 0; y < height; ++y) {
 517                         for (size_t x = 0; x < width; ++x, ++idx) {
 518                                 const BlockType &type = Type(BlockAt(idx));
 519                                 const Pos pos(x, y, z);
 520
 521                                 if (!type.visible || Obstructed(pos).All()) continue;
 522
 523                                 type.FillBlockModel(buf, ToTransform(pos, idx), vtx_counter);
 524                                 size_t vtx_begin = vtx_counter;
 525                                 vtx_counter += type.shape->VertexCount();
 526
 527                                 for (size_t vtx = vtx_begin; vtx < vtx_counter; ++vtx) {
 528                                         buf.lights.emplace_back(GetVertexLight(
 529                                                 pos,
 530                                                 buf.vertices[vtx],
 531                                                 type.shape->VertexNormal(vtx - vtx_begin, BlockAt(idx).Transform())
 532                                         ));
 533                                 }
 534                         }
 535                 }
 536         }
 537
 538         model.Update(buf);
 539         ClearModel();
 540 }
 541
 542 Block::FaceSet Chunk::Obstructed(const Pos &pos) const noexcept {
 543         Block::FaceSet result;
 544
 545         for (int f = 0; f < Block::FACE_COUNT; ++f) {
 546                 Block::Face face = Block::Face(f);
 547                 BlockLookup next(const_cast<Chunk *>(this), pos, face);
 548                 if (next && next.GetType().FaceFilled(next.GetBlock(), Block::Opposite(face))) {
 549                         result.Set(face);
 550                 }
 551         }
 552
 553         return result;
 554 }
 555
 556 glm::mat4 Chunk::ToTransform(const Pos &pos, int idx) const noexcept {
 557         return glm::translate(ToCoords(pos)) * BlockAt(idx).Transform();
 558 }
 559
 560
 561 BlockLookup::BlockLookup(Chunk *c, const Chunk::Pos &p) noexcept
 562 : chunk(c), pos(p) {
 563         while (pos.x >= Chunk::width) {
 564                 if (chunk->HasNeighbor(Block::FACE_RIGHT)) {
 565                         chunk = &chunk->GetNeighbor(Block::FACE_RIGHT);
 566                         pos.x -= Chunk::width;
 567                 } else {
 568                         chunk = nullptr;
 569                         return;
 570                 }
 571         }
 572         while (pos.x < 0) {
 573                 if (chunk->HasNeighbor(Block::FACE_LEFT)) {
 574                         chunk = &chunk->GetNeighbor(Block::FACE_LEFT);
 575                         pos.x += Chunk::width;
 576                 } else {
 577                         chunk = nullptr;
 578                         return;
 579                 }
 580         }
 581         while (pos.y >= Chunk::height) {
 582                 if (chunk->HasNeighbor(Block::FACE_UP)) {
 583                         chunk = &chunk->GetNeighbor(Block::FACE_UP);
 584                         pos.y -= Chunk::height;
 585                 } else {
 586                         chunk = nullptr;
 587                         return;
 588                 }
 589         }
 590         while (pos.y < 0) {
 591                 if (chunk->HasNeighbor(Block::FACE_DOWN)) {
 592                         chunk = &chunk->GetNeighbor(Block::FACE_DOWN);
 593                         pos.y += Chunk::height;
 594                 } else {
 595                         chunk = nullptr;
 596                         return;
 597                 }
 598         }
 599         while (pos.z >= Chunk::depth) {
 600                 if (chunk->HasNeighbor(Block::FACE_FRONT)) {
 601                         chunk = &chunk->GetNeighbor(Block::FACE_FRONT);
 602                         pos.z -= Chunk::depth;
 603                 } else {
 604                         chunk = nullptr;
 605                         return;
 606                 }
 607         }
 608         while (pos.z < 0) {
 609                 if (chunk->HasNeighbor(Block::FACE_BACK)) {
 610                         chunk = &chunk->GetNeighbor(Block::FACE_BACK);
 611                         pos.z += Chunk::depth;
 612                 } else {
 613                         chunk = nullptr;
 614                         return;
 615                 }
 616         }
 617 }
 618
 619 BlockLookup::BlockLookup(Chunk *c, const Chunk::Pos &p, Block::Face face) noexcept
 620 : chunk(c), pos(p) {
 621         pos += Block::FaceNormal(face);
 622         if (!Chunk::InBounds(pos)) {
 623                 pos -= Block::FaceNormal(face) * Chunk::Extent();
 624                 chunk = &chunk->GetNeighbor(face);
 625         }
 626 }
 627
 628
 629 ChunkLoader::ChunkLoader(
 630         const Config &config,
 631         const BlockTypeRegistry &reg,
 632         const Generator &gen,
 633         const WorldSave &save
 634 ) noexcept
 635 : base(0, 0, 0)
 636 , reg(reg)
 637 , gen(gen)
 638 , save(save)
 639 , loaded()
 640 , to_load()
 641 , to_free()
 642 , gen_timer(config.gen_limit)
 643 , load_dist(config.load_dist)
 644 , unload_dist(config.unload_dist) {
 645         gen_timer.Start();
 646 }
 647
 648 namespace {
 649
 650 struct ChunkLess {
 651
 652         explicit ChunkLess(const Chunk::Pos &base) noexcept
 653         : base(base) { }
 654
 655         bool operator ()(const Chunk::Pos &a, const Chunk::Pos &b) const noexcept {
 656                 Chunk::Pos da(base - a);
 657                 Chunk::Pos db(base - b);
 658                 return
 659                         da.x * da.x + da.y * da.y + da.z * da.z <
 660                         db.x * db.x + db.y * db.y + db.z * db.z;
 661         }
 662
 663         Chunk::Pos base;
 664
 665 };
 666
 667 }
 668
 669 void ChunkLoader::Queue(const Chunk::Pos &from, const Chunk::Pos &to) {
 670         for (int z = from.z; z < to.z; ++z) {
 671                 for (int y = from.y; y < to.y; ++y) {
 672                         for (int x = from.x; x < to.x; ++x) {
 673                                 Chunk::Pos pos(x, y, z);
 674                                 if (Known(pos)) {
 675                                         continue;
 676                                 } else if (pos == base) {
 677                                         Load(pos);
 678
 679                                 //      light testing
 680                                 //      for (int i = 0; i < 16; ++i) {
 681                                 //              for (int j = 0; j < 16; ++j) {
 682                                 //                      loaded.back().SetBlock(Chunk::Pos{  i, j,  0 }, Block(1));
 683                                 //                      loaded.back().SetBlock(Chunk::Pos{  i, j, 15 }, Block(1));
 684                                 //                      loaded.back().SetBlock(Chunk::Pos{  0, j,  i }, Block(1));
 685                                 //                      loaded.back().SetBlock(Chunk::Pos{ 15, j,  i }, Block(1));
 686                                 //              }
 687                                 //      }
 688                                 //      loaded.back().SetBlock(Chunk::Pos{  1,  0,  1 }, Block(13));
 689                                 //      loaded.back().SetBlock(Chunk::Pos{ 14,  0,  1 }, Block(13));
 690                                 //      loaded.back().SetBlock(Chunk::Pos{  1,  0, 14 }, Block(13));
 691                                 //      loaded.back().SetBlock(Chunk::Pos{ 14,  0, 14 }, Block(13));
 692                                 //      loaded.back().SetBlock(Chunk::Pos{  1, 15,  1 }, Block(13));
 693                                 //      loaded.back().SetBlock(Chunk::Pos{ 14, 15,  1 }, Block(13));
 694                                 //      loaded.back().SetBlock(Chunk::Pos{  1, 15, 14 }, Block(13));
 695                                 //      loaded.back().SetBlock(Chunk::Pos{ 14, 15, 14 }, Block(13));
 696                                 //      loaded.back().SetBlock(Chunk::Pos{  7,  7,  0 }, Block(13));
 697                                 //      loaded.back().SetBlock(Chunk::Pos{  8,  7,  0 }, Block(13));
 698                                 //      loaded.back().SetBlock(Chunk::Pos{  7,  8,  0 }, Block(13));
 699                                 //      loaded.back().SetBlock(Chunk::Pos{  8,  8,  0 }, Block(13));
 700                                 //      loaded.back().SetBlock(Chunk::Pos{  7,  7, 15 }, Block(13));
 701                                 //      loaded.back().SetBlock(Chunk::Pos{  8,  7, 15 }, Block(13));
 702                                 //      loaded.back().SetBlock(Chunk::Pos{  7,  8, 15 }, Block(13));
 703                                 //      loaded.back().SetBlock(Chunk::Pos{  8,  8, 15 }, Block(13));
 704                                 //      loaded.back().SetBlock(Chunk::Pos{  0,  7,  7 }, Block(13));
 705                                 //      loaded.back().SetBlock(Chunk::Pos{  0,  7,  8 }, Block(13));
 706                                 //      loaded.back().SetBlock(Chunk::Pos{  0,  8,  7 }, Block(13));
 707                                 //      loaded.back().SetBlock(Chunk::Pos{  0,  8,  8 }, Block(13));
 708                                 //      loaded.back().SetBlock(Chunk::Pos{ 15,  7,  7 }, Block(13));
 709                                 //      loaded.back().SetBlock(Chunk::Pos{ 15,  7,  8 }, Block(13));
 710                                 //      loaded.back().SetBlock(Chunk::Pos{ 15,  8,  7 }, Block(13));
 711                                 //      loaded.back().SetBlock(Chunk::Pos{ 15,  8,  8 }, Block(13));
 712                                 //      loaded.back().Invalidate();
 713                                 //      loaded.back().CheckUpdate();
 714
 715                                 //      orientation testing
 716                                 //      for (int i = 0; i < Block::FACE_COUNT; ++i) {
 717                                 //              for (int j = 0; j < Block::TURN_COUNT; ++j) {
 718                                 //                      loaded.back().BlockAt(512 * j + 2 * i) = Block(3 * (j + 1), Block::Face(i), Block::Turn(j));
 719                                 //              }
 720                                 //      }
 721                                 //      loaded.back().Invalidate();
 722                                 //      loaded.back().CheckUpdate();
 723                                 } else {
 724                                         to_load.emplace_back(pos);
 725                                 }
 726                         }
 727                 }
 728         }
 729         to_load.sort(ChunkLess(base));
 730 }
 731
 732 Chunk &ChunkLoader::Load(const Chunk::Pos &pos) {
 733         loaded.emplace_back(reg);
 734         Chunk &chunk = loaded.back();
 735         chunk.Position(pos);
 736         if (save.Exists(pos)) {
 737                 save.Read(chunk);
 738         } else {
 739                 gen(chunk);
 740         }
 741         Insert(chunk);
 742         return chunk;
 743 }
 744
 745 void ChunkLoader::Insert(Chunk &chunk) noexcept {
 746         for (Chunk &other : loaded) {
 747                 chunk.SetNeighbor(other);
 748         }
 749 }
 750
 751 std::list<Chunk>::iterator ChunkLoader::Remove(std::list<Chunk>::iterator chunk) noexcept {
 752         // fetch next entry while chunk's still in the list
 753         std::list<Chunk>::iterator next = chunk;
 754         ++next;
 755         // unlink neighbors so they won't reference a dead chunk
 756         chunk->ClearNeighbors();
 757         // if it should be saved, do it now
 758         if (chunk->ShouldUpdateSave()) {
 759                 save.Write(*chunk);
 760         }
 761         // and move it from loaded to free list
 762         to_free.splice(to_free.end(), loaded, chunk);
 763         return next;
 764 }
 765
 766 Chunk *ChunkLoader::Loaded(const Chunk::Pos &pos) noexcept {
 767         for (Chunk &chunk : loaded) {
 768                 if (chunk.Position() == pos) {
 769                         return &chunk;
 770                 }
 771         }
 772         return nullptr;
 773 }
 774
 775 bool ChunkLoader::Queued(const Chunk::Pos &pos) noexcept {
 776         for (const Chunk::Pos &chunk : to_load) {
 777                 if (chunk == pos) {
 778                         return true;
 779                 }
 780         }
 781         return false;
 782 }
 783
 784 bool ChunkLoader::Known(const Chunk::Pos &pos) noexcept {
 785         if (Loaded(pos)) return true;
 786         return Queued(pos);
 787 }
 788
 789 Chunk &ChunkLoader::ForceLoad(const Chunk::Pos &pos) {
 790         Chunk *chunk = Loaded(pos);
 791         if (chunk) {
 792                 return *chunk;
 793         }
 794
 795         for (auto iter(to_load.begin()), end(to_load.end()); iter != end; ++iter) {
 796                 if (*iter == pos) {
 797                         to_load.erase(iter);
 798                         break;
 799                 }
 800         }
 801
 802         return Load(pos);
 803 }
 804
 805 bool ChunkLoader::OutOfRange(const Chunk::Pos &pos) const noexcept {
 806         return std::abs(base.x - pos.x) > unload_dist
 807                         || std::abs(base.y - pos.y) > unload_dist
 808                         || std::abs(base.z - pos.z) > unload_dist;
 809 }
 810
 811 void ChunkLoader::Rebase(const Chunk::Pos &new_base) {
 812         if (new_base == base) {
 813                 return;
 814         }
 815         base = new_base;
 816
 817         // unload far away chunks
 818         for (auto iter(loaded.begin()), end(loaded.end()); iter != end;) {
 819                 if (OutOfRange(*iter)) {
 820                         iter = Remove(iter);
 821                 } else {
 822                         ++iter;
 823                 }
 824         }
 825         // abort far away queued chunks
 826         for (auto iter(to_load.begin()), end(to_load.end()); iter != end;) {
 827                 if (OutOfRange(*iter)) {
 828                         iter = to_load.erase(iter);
 829                 } else {
 830                         ++iter;
 831                 }
 832         }
 833         // add missing new chunks
 834         QueueSurrounding(base);
 835 }
 836
 837 void ChunkLoader::QueueSurrounding(const Chunk::Pos &pos) {
 838         const Chunk::Pos offset(load_dist, load_dist, load_dist);
 839         Queue(pos - offset, pos + offset);
 840 }
 841
 842 void ChunkLoader::Update(int dt) {
 843         // check if a chunk load is scheduled for this frame
 844         // and if there's chunks waiting to be loaded
 845         gen_timer.Update(dt);
 846         if (gen_timer.Hit()) {
 847                 // we may
 848                 // load until one of load or generation limits was hit
 849                 constexpr int max_load = 10;
 850                 constexpr int max_gen = 1;
 851                 int loaded = 0;
 852                 int generated = 0;
 853                 while (!to_load.empty() && loaded < max_load && generated < max_gen) {
 854                         if (LoadOne()) {
 855                                 ++generated;
 856                         } else {
 857                                 ++loaded;
 858                         }
 859                 }
 860         }
 861
 862         constexpr int max_save = 10;
 863         int saved = 0;
 864         for (Chunk &chunk : loaded) {
 865                 if (chunk.ShouldUpdateSave()) {
 866                         save.Write(chunk);
 867                         ++saved;
 868                         if (saved >= max_save) {
 869                                 break;
 870                         }
 871                 }
 872         }
 873 }
 874
 875 void ChunkLoader::LoadN(std::size_t n) {
 876         std::size_t end = std::min(n, ToLoad());
 877         for (std::size_t i = 0; i < end; ++i) {
 878                 LoadOne();
 879         }
 880 }
 881
 882 bool ChunkLoader::LoadOne() {
 883         if (to_load.empty()) return false;
 884
 885         // take position of next chunk in queue
 886         Chunk::Pos pos(to_load.front());
 887         to_load.pop_front();
 888
 889         // look if the same chunk was already generated and still lingering
 890         for (auto iter(to_free.begin()), end(to_free.end()); iter != end; ++iter) {
 891                 if (iter->Position() == pos) {
 892                         loaded.splice(loaded.end(), to_free, iter);
 893                         Insert(loaded.back());
 894                         return false;
 895                 }
 896         }
 897
 898         // if the free list is empty, allocate a new chunk
 899         // otherwise clear an unused one
 900         if (to_free.empty()) {
 901                 loaded.emplace_back(reg);
 902         } else {
 903                 to_free.front().ClearNeighbors();
 904                 loaded.splice(loaded.end(), to_free, to_free.begin());
 905         }
 906
 907         bool generated = false;
 908         Chunk &chunk = loaded.back();
 909         chunk.Position(pos);
 910         if (save.Exists(pos)) {
 911                 save.Read(chunk);
 912         } else {
 913                 gen(chunk);
 914                 generated = true;
 915         }
 916         Insert(chunk);
 917         return generated;
 918 }
 919
 920 }