src/chunk.cpp

   1 #include "chunk.hpp"
   2
   3 #include "generator.hpp"
   4
   5 #include <limits>
   6 #include <queue>
   7 #include <glm/gtx/transform.hpp>
   8
   9
  10 namespace blank {
  11
  12 Chunk::Chunk(const BlockTypeRegistry &types)
  13 : types(&types)
  14 , neighbor{ 0, 0, 0, 0, 0, 0 }
  15 , blocks()
  16 , light()
  17 , model()
  18 , position(0, 0, 0)
  19 , dirty(false) {
  20
  21 }
  22
  23 Chunk::Chunk(Chunk &&other)
  24 : types(other.types)
  25 , blocks(std::move(other.blocks))
  26 , light(std::move(other.light))
  27 , model(std::move(other.model))
  28 , position(other.position)
  29 , dirty(other.dirty) {
  30         for (size_t i = 0; i < Block::FACE_COUNT; ++i) {
  31                 neighbor[i] = other.neighbor[i];
  32         }
  33 }
  34
  35 Chunk &Chunk::operator =(Chunk &&other) {
  36         types = other.types;
  37         for (size_t i = 0; i < Block::FACE_COUNT; ++i) {
  38                 neighbor[i] = other.neighbor[i];
  39         }
  40         blocks = std::move(other.blocks);
  41         light = std::move(other.light);
  42         model = std::move(other.model);
  43         position = other.position;
  44         dirty = other.dirty;
  45         return *this;
  46 }
  47
  48
  49 namespace {
  50
  51 struct SetNode {
  52
  53         Chunk *chunk;
  54         Chunk::Pos pos;
  55
  56         SetNode(Chunk *chunk, Chunk::Pos pos)
  57         : chunk(chunk), pos(pos) { }
  58
  59         int Get() const { return chunk->GetLight(pos); }
  60         void Set(int level) { chunk->SetLight(pos, level); }
  61
  62         bool HasNext(Block::Face face) {
  63                 const BlockLookup next(chunk, pos, face);
  64                 return next && !next.GetType().block_light;
  65         }
  66         SetNode GetNext(Block::Face face) {
  67                 const BlockLookup next(chunk, pos, face);
  68                 return SetNode(&next.GetChunk(), next.GetBlockPos());
  69         }
  70
  71 };
  72
  73 struct UnsetNode
  74 : public SetNode {
  75
  76         int level;
  77
  78         UnsetNode(Chunk *chunk, Chunk::Pos pos)
  79         : SetNode(chunk, pos), level(Get()) { }
  80
  81         UnsetNode(const SetNode &set)
  82         : SetNode(set), level(Get()) { }
  83
  84
  85         bool HasNext(Block::Face face) {
  86                 const BlockLookup next(chunk, pos, face);
  87                 return next;
  88         }
  89         UnsetNode GetNext(Block::Face face) { return UnsetNode(SetNode::GetNext(face)); }
  90
  91 };
  92
  93 std::queue<SetNode> light_queue;
  94 std::queue<UnsetNode> dark_queue;
  95
  96 void work_light() {
  97         while (!light_queue.empty()) {
  98                 SetNode node = light_queue.front();
  99                 light_queue.pop();
 100
 101                 int level = node.Get() - 1;
 102                 for (int face = 0; face < Block::FACE_COUNT; ++face) {
 103                         if (node.HasNext(Block::Face(face))) {
 104                                 SetNode other = node.GetNext(Block::Face(face));
 105                                 if (other.Get() < level) {
 106                                         other.Set(level);
 107                                         light_queue.emplace(other);
 108                                 }
 109                         }
 110                 }
 111         }
 112 }
 113
 114 void work_dark() {
 115         while (!dark_queue.empty()) {
 116                 UnsetNode node = dark_queue.front();
 117                 dark_queue.pop();
 118
 119                 for (int face = 0; face < Block::FACE_COUNT; ++face) {
 120                         if (node.HasNext(Block::Face(face))) {
 121                                 UnsetNode other = node.GetNext(Block::Face(face));
 122                                 // TODO: if there a light source here with the same level this will err
 123                                 if (other.Get() != 0 && other.Get() < node.level) {
 124                                         other.Set(0);
 125                                         dark_queue.emplace(other);
 126                                 } else {
 127                                         light_queue.emplace(other);
 128                                 }
 129                         }
 130                 }
 131         }
 132 }
 133
 134 }
 135
 136 void Chunk::SetBlock(int index, const Block &block) {
 137         const BlockType &old_type = Type(blocks[index]);
 138         const BlockType &new_type = Type(block);
 139
 140         blocks[index] = block;
 141
 142         if (&old_type == &new_type) return;
 143
 144         if (new_type.luminosity > old_type.luminosity) {
 145                 // light added
 146                 SetLight(index, new_type.luminosity);
 147                 light_queue.emplace(this, ToPos(index));
 148                 work_light();
 149         } else if (new_type.luminosity < old_type.luminosity) {
 150                 // light removed
 151                 dark_queue.emplace(this, ToPos(index));
 152                 SetLight(index, 0);
 153                 work_dark();
 154                 SetLight(index, new_type.luminosity);
 155                 light_queue.emplace(this, ToPos(index));
 156                 work_light();
 157         } else if (new_type.block_light && !old_type.block_light) {
 158                 // obstacle added
 159                 if (GetLight(index) > 0) {
 160                         dark_queue.emplace(this, ToPos(index));
 161                         SetLight(index, 0);
 162                         work_dark();
 163                         work_light();
 164                 }
 165         } else if (!new_type.block_light && old_type.block_light) {
 166                 // obstacle removed
 167                 int level = 0;
 168                 for (int face = 0; face < Block::FACE_COUNT; ++face) {
 169                         Pos next_pos(ToPos(index) + Block::FaceNormal(Block::Face(face)));
 170                         int next_level = 0;
 171                         if (InBounds(next_pos)) {
 172                                 next_level = GetLight(next_pos);
 173                         } else {
 174                                 if (HasNeighbor(Block::Face(face))) {
 175                                         next_pos -= (Block::FaceNormal(Block::Face(face)) * Chunk::Extent());
 176                                         next_level = GetNeighbor(Block::Face(face)).GetLight(next_pos);
 177                                 }
 178                         }
 179                         if (level < next_level) {
 180                                 level = next_level;
 181                         }
 182                 }
 183                 if (level > 1) {
 184                         SetLight(index, level - 1);
 185                         light_queue.emplace(this, ToPos(index));
 186                         work_light();
 187                 }
 188         }
 189 }
 190
 191 const Block *Chunk::FindNext(const Pos &pos, Block::Face face) const {
 192         Pos next_pos(pos + Block::FaceNormal(face));
 193         if (InBounds(next_pos)) {
 194                 return &BlockAt(pos + Block::FaceNormal(face));
 195         } else if (HasNeighbor(face)) {
 196                 return &GetNeighbor(face).BlockAt(next_pos - (Block::FaceNormal(face) * Extent()));
 197         } else {
 198                 return nullptr;
 199         }
 200 }
 201
 202 void Chunk::SetNeighbor(Chunk &other) {
 203         if (other.position == position + Pos(-1, 0, 0)) {
 204                 if (neighbor[Block::FACE_LEFT] != &other) {
 205                         neighbor[Block::FACE_LEFT] = &other;
 206                         other.neighbor[Block::FACE_RIGHT] = this;
 207                         for (int z = 0; z < Depth(); ++z) {
 208                                 for (int y = 0; y < Height(); ++y) {
 209                                         Pos my_pos(0, y, z);
 210                                         Pos other_pos(Width() - 1, y, z);
 211                                         if (GetLight(my_pos) > 0) {
 212                                                 light_queue.emplace(this, my_pos);
 213                                         }
 214                                         if (other.GetLight(other_pos) > 0) {
 215                                                 light_queue.emplace(&other, other_pos);
 216                                         }
 217                                 }
 218                         }
 219                         work_light();
 220                 }
 221         } else if (other.position == position + Pos(1, 0, 0)) {
 222                 if (neighbor[Block::FACE_RIGHT] != &other) {
 223                         neighbor[Block::FACE_RIGHT] = &other;
 224                         other.neighbor[Block::FACE_LEFT] = this;
 225                         for (int z = 0; z < Depth(); ++z) {
 226                                 for (int y = 0; y < Height(); ++y) {
 227                                         Pos my_pos(Width() - 1, y, z);
 228                                         Pos other_pos(0, y, z);
 229                                         if (GetLight(my_pos) > 0) {
 230                                                 light_queue.emplace(this, my_pos);
 231                                         }
 232                                         if (other.GetLight(other_pos) > 0) {
 233                                                 light_queue.emplace(&other, other_pos);
 234                                         }
 235                                 }
 236                         }
 237                         work_light();
 238                 }
 239         } else if (other.position == position + Pos(0, -1, 0)) {
 240                 if (neighbor[Block::FACE_DOWN] != &other) {
 241                         neighbor[Block::FACE_DOWN] = &other;
 242                         other.neighbor[Block::FACE_UP] = this;
 243                         for (int z = 0; z < Depth(); ++z) {
 244                                 for (int x = 0; x < Width(); ++x) {
 245                                         Pos my_pos(x, 0, z);
 246                                         Pos other_pos(x, Height() - 1, z);
 247                                         if (GetLight(my_pos) > 0) {
 248                                                 light_queue.emplace(this, my_pos);
 249                                         }
 250                                         if (other.GetLight(other_pos) > 0) {
 251                                                 light_queue.emplace(&other, other_pos);
 252                                         }
 253                                 }
 254                         }
 255                         work_light();
 256                 }
 257         } else if (other.position == position + Pos(0, 1, 0)) {
 258                 if (neighbor[Block::FACE_UP] != &other) {
 259                         neighbor[Block::FACE_UP] = &other;
 260                         other.neighbor[Block::FACE_DOWN] = this;
 261                         for (int z = 0; z < Depth(); ++z) {
 262                                 for (int x = 0; x < Width(); ++x) {
 263                                         Pos my_pos(x, Height() - 1, z);
 264                                         Pos other_pos(x, 0, z);
 265                                         if (GetLight(my_pos) > 0) {
 266                                                 light_queue.emplace(this, my_pos);
 267                                         }
 268                                         if (other.GetLight(other_pos) > 0) {
 269                                                 light_queue.emplace(&other, other_pos);
 270                                         }
 271                                 }
 272                         }
 273                         work_light();
 274                 }
 275         } else if (other.position == position + Pos(0, 0, -1)) {
 276                 if (neighbor[Block::FACE_BACK] != &other) {
 277                         neighbor[Block::FACE_BACK] = &other;
 278                         other.neighbor[Block::FACE_FRONT] = this;
 279                         for (int y = 0; y < Height(); ++y) {
 280                                 for (int x = 0; x < Width(); ++x) {
 281                                         Pos my_pos(x, y, 0);
 282                                         Pos other_pos(x, y, Depth() - 1);
 283                                         if (GetLight(my_pos) > 0) {
 284                                                 light_queue.emplace(this, my_pos);
 285                                         }
 286                                         if (other.GetLight(other_pos) > 0) {
 287                                                 light_queue.emplace(&other, other_pos);
 288                                         }
 289                                 }
 290                         }
 291                         work_light();
 292                 }
 293         } else if (other.position == position + Pos(0, 0, 1)) {
 294                 if (neighbor[Block::FACE_FRONT] != &other) {
 295                         neighbor[Block::FACE_FRONT] = &other;
 296                         other.neighbor[Block::FACE_BACK] = this;
 297                         for (int y = 0; y < Height(); ++y) {
 298                                 for (int x = 0; x < Width(); ++x) {
 299                                         Pos my_pos(x, y, Depth() - 1);
 300                                         Pos other_pos(x, y, 0);
 301                                         if (GetLight(my_pos) > 0) {
 302                                                 light_queue.emplace(this, my_pos);
 303                                         }
 304                                         if (other.GetLight(other_pos) > 0) {
 305                                                 light_queue.emplace(&other, other_pos);
 306                                         }
 307                                 }
 308                         }
 309                         work_light();
 310                 }
 311         }
 312 }
 313
 314 void Chunk::ClearNeighbors() {
 315         for (int i = 0; i < Block::FACE_COUNT; ++i) {
 316                 neighbor[i] = nullptr;
 317         }
 318 }
 319
 320 void Chunk::Unlink() {
 321         if (neighbor[Block::FACE_UP]) {
 322                 neighbor[Block::FACE_UP]->neighbor[Block::FACE_DOWN] = nullptr;
 323         }
 324         if (neighbor[Block::FACE_DOWN]) {
 325                 neighbor[Block::FACE_DOWN]->neighbor[Block::FACE_UP] = nullptr;
 326         }
 327         if (neighbor[Block::FACE_LEFT]) {
 328                 neighbor[Block::FACE_LEFT]->neighbor[Block::FACE_RIGHT] = nullptr;
 329         }
 330         if (neighbor[Block::FACE_RIGHT]) {
 331                 neighbor[Block::FACE_RIGHT]->neighbor[Block::FACE_LEFT] = nullptr;
 332         }
 333         if (neighbor[Block::FACE_FRONT]) {
 334                 neighbor[Block::FACE_FRONT]->neighbor[Block::FACE_BACK] = nullptr;
 335         }
 336         if (neighbor[Block::FACE_BACK]) {
 337                 neighbor[Block::FACE_BACK]->neighbor[Block::FACE_FRONT] = nullptr;
 338         }
 339 }
 340
 341 void Chunk::Relink() {
 342         if (neighbor[Block::FACE_UP]) {
 343                 neighbor[Block::FACE_UP]->neighbor[Block::FACE_DOWN] = this;
 344         }
 345         if (neighbor[Block::FACE_DOWN]) {
 346                 neighbor[Block::FACE_DOWN]->neighbor[Block::FACE_UP] = this;
 347         }
 348         if (neighbor[Block::FACE_LEFT]) {
 349                 neighbor[Block::FACE_LEFT]->neighbor[Block::FACE_RIGHT] = this;
 350         }
 351         if (neighbor[Block::FACE_RIGHT]) {
 352                 neighbor[Block::FACE_RIGHT]->neighbor[Block::FACE_LEFT] = this;
 353         }
 354         if (neighbor[Block::FACE_FRONT]) {
 355                 neighbor[Block::FACE_FRONT]->neighbor[Block::FACE_BACK] = this;
 356         }
 357         if (neighbor[Block::FACE_BACK]) {
 358                 neighbor[Block::FACE_BACK]->neighbor[Block::FACE_FRONT] = this;
 359         }
 360 }
 361
 362
 363 void Chunk::SetLight(int index, int level) {
 364         if (light[index] != level) {
 365                 light[index] = level;
 366                 Invalidate();
 367         }
 368 }
 369
 370 int Chunk::GetLight(int index) const {
 371         return light[index];
 372 }
 373
 374 float Chunk::GetVertexLight(int index, const BlockModel::Position &vtx, const BlockModel::Normal &norm) const {
 375         float light = GetLight(index);
 376         Chunk::Pos pos(ToPos(index));
 377
 378         Block::Face direct_face(Block::NormalFace(norm));
 379         // tis okay
 380         BlockLookup direct(const_cast<Chunk *>(this), pos, Block::NormalFace(norm));
 381         if (direct) {
 382                 float direct_light = direct.GetLight();
 383                 if (direct_light > light) {
 384                         light = direct_light;
 385                 }
 386         }
 387
 388         // cheap alternative until AO etc are implemented
 389         // to tell the faces apart
 390
 391         if (direct_face == Block::FACE_LEFT || direct_face == Block::FACE_RIGHT) {
 392                 light -= 0.2;
 393         } else if (direct_face == Block::FACE_FRONT || direct_face == Block::FACE_BACK) {
 394                 light -= 0.4;
 395         }
 396
 397         return light;
 398 }
 399
 400
 401 bool Chunk::IsSurface(const Pos &pos) const {
 402         const Block &block = BlockAt(pos);
 403         if (!Type(block).visible) {
 404                 return false;
 405         }
 406         for (int face = 0; face < Block::FACE_COUNT; ++face) {
 407                 const Block *next = FindNext(pos, Block::Face(face));
 408                 if (!next || !Type(*next).visible) {
 409                         return true;
 410                 }
 411         }
 412         return false;
 413 }
 414
 415
 416 void Chunk::Allocate() {
 417         blocks.resize(Size(), Block(0));
 418         light.resize(Size(), 0);
 419 }
 420
 421
 422 void Chunk::Draw() {
 423         if (dirty) {
 424                 Update();
 425         }
 426         model.Draw();
 427 }
 428
 429
 430 bool Chunk::Intersection(
 431         const Ray &ray,
 432         const glm::mat4 &M,
 433         int &blkid,
 434         float &dist,
 435         glm::vec3 &normal
 436 ) const {
 437         // TODO: should be possible to heavily optimize this
 438         int id = 0;
 439         blkid = -1;
 440         dist = std::numeric_limits<float>::infinity();
 441         for (int z = 0; z < Depth(); ++z) {
 442                 for (int y = 0; y < Height(); ++y) {
 443                         for (int x = 0; x < Width(); ++x, ++id) {
 444                                 if (!Type(blocks[id]).visible) {
 445                                         continue;
 446                                 }
 447                                 float cur_dist;
 448                                 glm::vec3 cur_norm;
 449                                 if (Type(blocks[id]).shape->Intersects(ray, M * ToTransform(id), cur_dist, cur_norm)) {
 450                                         if (cur_dist < dist) {
 451                                                 blkid = id;
 452                                                 dist = cur_dist;
 453                                                 normal = cur_norm;
 454                                         }
 455                                 }
 456                         }
 457                 }
 458         }
 459
 460         if (blkid < 0) {
 461                 return false;
 462         } else {
 463                 normal = glm::vec3(BlockAt(blkid).Transform() * glm::vec4(normal, 0.0f));
 464                 return true;
 465         }
 466 }
 467
 468 void Chunk::Position(const Pos &pos) {
 469         position = pos;
 470 }
 471
 472 glm::mat4 Chunk::Transform(const Pos &offset) const {
 473         return glm::translate((position - offset) * Extent());
 474 }
 475
 476
 477 namespace {
 478
 479 BlockModel::Buffer buf;
 480
 481 }
 482
 483 void Chunk::CheckUpdate() {
 484         if (dirty) {
 485                 Update();
 486         }
 487 }
 488
 489 void Chunk::Update() {
 490         int vtx_count = 0, idx_count = 0;
 491         for (const auto &block : blocks) {
 492                 const Shape *shape = Type(block).shape;
 493                 vtx_count += shape->VertexCount();
 494                 idx_count += shape->VertexIndexCount();
 495         }
 496         buf.Clear();
 497         buf.Reserve(vtx_count, idx_count);
 498
 499         BlockModel::Index vtx_counter = 0;
 500         for (size_t i = 0; i < Size(); ++i) {
 501                 const BlockType &type = Type(blocks[i]);
 502
 503                 if (!type.visible || Obstructed(i)) continue;
 504
 505                 type.FillBlockModel(buf, ToTransform(i), vtx_counter);
 506                 size_t vtx_begin = vtx_counter;
 507                 vtx_counter += type.shape->VertexCount();
 508
 509                 for (size_t vtx = vtx_begin; vtx < vtx_counter; ++vtx) {
 510                         buf.lights.emplace_back(GetVertexLight(i, buf.vertices[vtx], buf.normals[vtx]));
 511                 }
 512         }
 513
 514         model.Update(buf);
 515         dirty = false;
 516 }
 517
 518 bool Chunk::Obstructed(int idx) const {
 519         Chunk::Pos pos(ToPos(idx));
 520
 521         Chunk::Pos left_pos(pos + Chunk::Pos(-1, 0, 0));
 522         const Block *left_block = nullptr;
 523         if (InBounds(left_pos)) {
 524                 left_block = &BlockAt(left_pos);
 525         } else if (HasNeighbor(Block::FACE_LEFT)) {
 526                 left_pos += Chunk::Pos(Width(), 0, 0);
 527                 left_block = &GetNeighbor(Block::FACE_LEFT).BlockAt(left_pos);
 528         } else {
 529                 return false;
 530         }
 531         if (!Type(*left_block).FaceFilled(*left_block, Block::FACE_RIGHT)) {
 532                 return false;
 533         }
 534
 535         Chunk::Pos right_pos(pos + Chunk::Pos(1, 0, 0));
 536         const Block *right_block = nullptr;
 537         if (InBounds(right_pos)) {
 538                 right_block = &BlockAt(right_pos);
 539         } else if (HasNeighbor(Block::FACE_RIGHT)) {
 540                 right_pos += Chunk::Pos(-Width(), 0, 0);
 541                 right_block = &GetNeighbor(Block::FACE_RIGHT).BlockAt(right_pos);
 542         } else {
 543                 return false;
 544         }
 545         if (!Type(*right_block).FaceFilled(*right_block, Block::FACE_LEFT)) {
 546                 return false;
 547         }
 548
 549         Chunk::Pos down_pos(pos + Chunk::Pos(0, -1, 0));
 550         const Block *down_block = nullptr;
 551         if (InBounds(down_pos)) {
 552                 down_block = &BlockAt(down_pos);
 553         } else if (HasNeighbor(Block::FACE_DOWN)) {
 554                 down_pos += Chunk::Pos(0, Height(), 0);
 555                 down_block = &GetNeighbor(Block::FACE_DOWN).BlockAt(down_pos);
 556         } else {
 557                 return false;
 558         }
 559         if (!Type(*down_block).FaceFilled(*down_block, Block::FACE_UP)) {
 560                 return false;
 561         }
 562
 563         Chunk::Pos up_pos(pos + Chunk::Pos(0, 1, 0));
 564         const Block *up_block = nullptr;
 565         if (InBounds(up_pos)) {
 566                 up_block = &BlockAt(up_pos);
 567         } else if (HasNeighbor(Block::FACE_UP)) {
 568                 up_pos += Chunk::Pos(0, -Height(), 0);
 569                 up_block = &GetNeighbor(Block::FACE_UP).BlockAt(up_pos);
 570         } else {
 571                 return false;
 572         }
 573         if (!Type(*up_block).FaceFilled(*up_block, Block::FACE_DOWN)) {
 574                 return false;
 575         }
 576
 577         Chunk::Pos back_pos(pos + Chunk::Pos(0, 0, -1));
 578         const Block *back_block = nullptr;
 579         if (InBounds(back_pos)) {
 580                 back_block = &BlockAt(back_pos);
 581         } else if (HasNeighbor(Block::FACE_BACK)) {
 582                 back_pos += Chunk::Pos(0, 0, Depth());
 583                 back_block = &GetNeighbor(Block::FACE_BACK).BlockAt(back_pos);
 584         } else {
 585                 return false;
 586         }
 587         if (!Type(*back_block).FaceFilled(*back_block, Block::FACE_FRONT)) {
 588                 return false;
 589         }
 590
 591         Chunk::Pos front_pos(pos + Chunk::Pos(0, 0, 1));
 592         const Block *front_block = nullptr;
 593         if (InBounds(front_pos)) {
 594                 front_block = &BlockAt(front_pos);
 595         } else if (HasNeighbor(Block::FACE_FRONT)) {
 596                 front_pos += Chunk::Pos(0, 0, -Depth());
 597                 front_block = &GetNeighbor(Block::FACE_FRONT).BlockAt(front_pos);
 598         } else {
 599                 return false;
 600         }
 601         if (!Type(*front_block).FaceFilled(*front_block, Block::FACE_BACK)) {
 602                 return false;
 603         }
 604
 605         return true;
 606 }
 607
 608 glm::mat4 Chunk::ToTransform(int idx) const {
 609         return glm::translate(glm::mat4(1.0f), ToCoords(idx)) * blocks[idx].Transform();
 610 }
 611
 612
 613 BlockLookup::BlockLookup(Chunk *c, const Chunk::Pos &p)
 614 : chunk(c), pos(p) {
 615         while (pos.x >= Chunk::Width()) {
 616                 if (chunk->HasNeighbor(Block::FACE_RIGHT)) {
 617                         chunk = &chunk->GetNeighbor(Block::FACE_RIGHT);
 618                         pos.x -= Chunk::Width();
 619                 } else {
 620                         chunk = nullptr;
 621                         return;
 622                 }
 623         }
 624         while (pos.x < 0) {
 625                 if (chunk->HasNeighbor(Block::FACE_LEFT)) {
 626                         chunk = &chunk->GetNeighbor(Block::FACE_LEFT);
 627                         pos.x += Chunk::Width();
 628                 } else {
 629                         chunk = nullptr;
 630                         return;
 631                 }
 632         }
 633         while (pos.y >= Chunk::Height()) {
 634                 if (chunk->HasNeighbor(Block::FACE_UP)) {
 635                         chunk = &chunk->GetNeighbor(Block::FACE_UP);
 636                         pos.y -= Chunk::Height();
 637                 } else {
 638                         chunk = nullptr;
 639                         return;
 640                 }
 641         }
 642         while (pos.y < 0) {
 643                 if (chunk->HasNeighbor(Block::FACE_DOWN)) {
 644                         chunk = &chunk->GetNeighbor(Block::FACE_DOWN);
 645                         pos.y += Chunk::Height();
 646                 } else {
 647                         chunk = nullptr;
 648                         return;
 649                 }
 650         }
 651         while (pos.z >= Chunk::Depth()) {
 652                 if (chunk->HasNeighbor(Block::FACE_FRONT)) {
 653                         chunk = &chunk->GetNeighbor(Block::FACE_FRONT);
 654                         pos.z -= Chunk::Depth();
 655                 } else {
 656                         chunk = nullptr;
 657                         return;
 658                 }
 659         }
 660         while (pos.z < 0) {
 661                 if (chunk->HasNeighbor(Block::FACE_BACK)) {
 662                         chunk = &chunk->GetNeighbor(Block::FACE_BACK);
 663                         pos.z += Chunk::Depth();
 664                 } else {
 665                         chunk = nullptr;
 666                         return;
 667                 }
 668         }
 669 }
 670
 671 BlockLookup::BlockLookup(Chunk *c, const Chunk::Pos &p, Block::Face face)
 672 : chunk(c), pos(p) {
 673         pos += Block::FaceNormal(face);
 674         if (!Chunk::InBounds(pos)) {
 675                 pos -= Block::FaceNormal(face) * Chunk::Extent();
 676                 chunk = &chunk->GetNeighbor(face);
 677         }
 678 }
 679
 680
 681 ChunkLoader::ChunkLoader(const Config &config, const BlockTypeRegistry &reg, const Generator &gen)
 682 : base(0, 0, 0)
 683 , reg(reg)
 684 , gen(gen)
 685 , loaded()
 686 , to_generate()
 687 , to_free()
 688 , load_dist(config.load_dist)
 689 , unload_dist(config.unload_dist) {
 690
 691 }
 692
 693 namespace {
 694
 695 struct ChunkLess {
 696
 697         explicit ChunkLess(const Chunk::Pos &base)
 698         : base(base) { }
 699
 700         bool operator ()(const Chunk::Pos &a, const Chunk::Pos &b) const {
 701                 Chunk::Pos da(base - a);
 702                 Chunk::Pos db(base - b);
 703                 return
 704                         da.x * da.x + da.y * da.y + da.z * da.z <
 705                         db.x * db.x + db.y * db.y + db.z * db.z;
 706         }
 707
 708         Chunk::Pos base;
 709
 710 };
 711
 712 }
 713
 714 void ChunkLoader::Generate(const Chunk::Pos &from, const Chunk::Pos &to) {
 715         for (int z = from.z; z < to.z; ++z) {
 716                 for (int y = from.y; y < to.y; ++y) {
 717                         for (int x = from.x; x < to.x; ++x) {
 718                                 Chunk::Pos pos(x, y, z);
 719                                 if (Known(pos)) {
 720                                         continue;
 721                                 } else if (pos == base) {
 722                                         Generate(pos);
 723
 724                                 //      light testing
 725                                 //      for (int i = 0; i < 16; ++i) {
 726                                 //              for (int j = 0; j < 16; ++j) {
 727                                 //                      loaded.back().SetBlock(Chunk::Pos{  i, j,  0 }, Block(1));
 728                                 //                      loaded.back().SetBlock(Chunk::Pos{  i, j, 15 }, Block(1));
 729                                 //                      loaded.back().SetBlock(Chunk::Pos{  0, j,  i }, Block(1));
 730                                 //                      loaded.back().SetBlock(Chunk::Pos{ 15, j,  i }, Block(1));
 731                                 //              }
 732                                 //      }
 733                                 //      loaded.back().SetBlock(Chunk::Pos{  1,  0,  1 }, Block(13));
 734                                 //      loaded.back().SetBlock(Chunk::Pos{ 14,  0,  1 }, Block(13));
 735                                 //      loaded.back().SetBlock(Chunk::Pos{  1,  0, 14 }, Block(13));
 736                                 //      loaded.back().SetBlock(Chunk::Pos{ 14,  0, 14 }, Block(13));
 737                                 //      loaded.back().SetBlock(Chunk::Pos{  1, 15,  1 }, Block(13));
 738                                 //      loaded.back().SetBlock(Chunk::Pos{ 14, 15,  1 }, Block(13));
 739                                 //      loaded.back().SetBlock(Chunk::Pos{  1, 15, 14 }, Block(13));
 740                                 //      loaded.back().SetBlock(Chunk::Pos{ 14, 15, 14 }, Block(13));
 741                                 //      loaded.back().SetBlock(Chunk::Pos{  7,  7,  0 }, Block(13));
 742                                 //      loaded.back().SetBlock(Chunk::Pos{  8,  7,  0 }, Block(13));
 743                                 //      loaded.back().SetBlock(Chunk::Pos{  7,  8,  0 }, Block(13));
 744                                 //      loaded.back().SetBlock(Chunk::Pos{  8,  8,  0 }, Block(13));
 745                                 //      loaded.back().SetBlock(Chunk::Pos{  7,  7, 15 }, Block(13));
 746                                 //      loaded.back().SetBlock(Chunk::Pos{  8,  7, 15 }, Block(13));
 747                                 //      loaded.back().SetBlock(Chunk::Pos{  7,  8, 15 }, Block(13));
 748                                 //      loaded.back().SetBlock(Chunk::Pos{  8,  8, 15 }, Block(13));
 749                                 //      loaded.back().SetBlock(Chunk::Pos{  0,  7,  7 }, Block(13));
 750                                 //      loaded.back().SetBlock(Chunk::Pos{  0,  7,  8 }, Block(13));
 751                                 //      loaded.back().SetBlock(Chunk::Pos{  0,  8,  7 }, Block(13));
 752                                 //      loaded.back().SetBlock(Chunk::Pos{  0,  8,  8 }, Block(13));
 753                                 //      loaded.back().SetBlock(Chunk::Pos{ 15,  7,  7 }, Block(13));
 754                                 //      loaded.back().SetBlock(Chunk::Pos{ 15,  7,  8 }, Block(13));
 755                                 //      loaded.back().SetBlock(Chunk::Pos{ 15,  8,  7 }, Block(13));
 756                                 //      loaded.back().SetBlock(Chunk::Pos{ 15,  8,  8 }, Block(13));
 757                                 //      loaded.back().Invalidate();
 758                                 //      loaded.back().CheckUpdate();
 759
 760                                 //      orientation testing
 761                                 //      for (int i = 0; i < Block::FACE_COUNT; ++i) {
 762                                 //              for (int j = 0; j < Block::TURN_COUNT; ++j) {
 763                                 //                      loaded.back().BlockAt(512 * j + 2 * i) = Block(3 * (j + 1), Block::Face(i), Block::Turn(j));
 764                                 //              }
 765                                 //      }
 766                                 //      loaded.back().Invalidate();
 767                                 //      loaded.back().CheckUpdate();
 768                                 } else {
 769                                         to_generate.emplace_back(pos);
 770                                 }
 771                         }
 772                 }
 773         }
 774         to_generate.sort(ChunkLess(base));
 775 }
 776
 777 Chunk &ChunkLoader::Generate(const Chunk::Pos &pos) {
 778         loaded.emplace_back(reg);
 779         Chunk &chunk = loaded.back();
 780         chunk.Position(pos);
 781         chunk.Allocate();
 782         gen(chunk);
 783         Insert(chunk);
 784         return chunk;
 785 }
 786
 787 void ChunkLoader::Insert(Chunk &chunk) {
 788         for (Chunk &other : loaded) {
 789                 chunk.SetNeighbor(other);
 790         }
 791 }
 792
 793 void ChunkLoader::Remove(Chunk &chunk) {
 794         chunk.Unlink();
 795 }
 796
 797 Chunk *ChunkLoader::Loaded(const Chunk::Pos &pos) {
 798         for (Chunk &chunk : loaded) {
 799                 if (chunk.Position() == pos) {
 800                         return &chunk;
 801                 }
 802         }
 803         return nullptr;
 804 }
 805
 806 bool ChunkLoader::Queued(const Chunk::Pos &pos) {
 807         for (const Chunk::Pos &chunk : to_generate) {
 808                 if (chunk == pos) {
 809                         return true;
 810                 }
 811         }
 812         return nullptr;
 813 }
 814
 815 bool ChunkLoader::Known(const Chunk::Pos &pos) {
 816         if (Loaded(pos)) return true;
 817         return Queued(pos);
 818 }
 819
 820 Chunk &ChunkLoader::ForceLoad(const Chunk::Pos &pos) {
 821         Chunk *chunk = Loaded(pos);
 822         if (chunk) {
 823                 return *chunk;
 824         }
 825
 826         for (auto iter(to_generate.begin()), end(to_generate.end()); iter != end; ++iter) {
 827                 if (*iter == pos) {
 828                         to_generate.erase(iter);
 829                         break;
 830                 }
 831         }
 832
 833         return Generate(pos);
 834 }
 835
 836 void ChunkLoader::Rebase(const Chunk::Pos &new_base) {
 837         if (new_base == base) {
 838                 return;
 839         }
 840         base = new_base;
 841
 842         // unload far away chunks
 843         for (auto iter(loaded.begin()), end(loaded.end()); iter != end;) {
 844                 if (std::abs(base.x - iter->Position().x) > unload_dist
 845                                 || std::abs(base.y - iter->Position().y) > unload_dist
 846                                 || std::abs(base.z - iter->Position().z) > unload_dist) {
 847                         auto saved = iter;
 848                         Remove(*saved);
 849                         ++iter;
 850                         to_free.splice(to_free.end(), loaded, saved);
 851                 } else {
 852                         ++iter;
 853                 }
 854         }
 855         // abort far away queued chunks
 856         for (auto iter(to_generate.begin()), end(to_generate.end()); iter != end;) {
 857                 if (std::abs(base.x - iter->x) > unload_dist
 858                                 || std::abs(base.y - iter->y) > unload_dist
 859                                 || std::abs(base.z - iter->z) > unload_dist) {
 860                         iter = to_generate.erase(iter);
 861                 } else {
 862                         ++iter;
 863                 }
 864         }
 865         // add missing new chunks
 866         GenerateSurrounding(base);
 867 }
 868
 869 void ChunkLoader::GenerateSurrounding(const Chunk::Pos &pos) {
 870         const Chunk::Pos offset(load_dist, load_dist, load_dist);
 871         Generate(pos - offset, pos + offset);
 872 }
 873
 874 void ChunkLoader::Update() {
 875         bool reused = false;
 876         if (!to_generate.empty()) {
 877                 Chunk::Pos pos(to_generate.front());
 878
 879                 for (auto iter(to_free.begin()), end(to_free.end()); iter != end; ++iter) {
 880                         if (iter->Position() == pos) {
 881                                 iter->Relink();
 882                                 loaded.splice(loaded.end(), to_free, iter);
 883                                 reused = true;
 884                                 break;
 885                         }
 886                 }
 887
 888                 if (!reused) {
 889                         if (to_free.empty()) {
 890                                 loaded.emplace_back(reg);
 891                         } else {
 892                                 to_free.front().ClearNeighbors();
 893                                 loaded.splice(loaded.end(), to_free, to_free.begin());
 894                                 reused = true;
 895                         }
 896                         Chunk &chunk = loaded.back();
 897                         chunk.Position(pos);
 898                         chunk.Allocate();
 899                         gen(chunk);
 900                         Insert(chunk);
 901                 }
 902                 to_generate.pop_front();
 903         }
 904
 905         if (!reused && !to_free.empty()) {
 906                 to_free.pop_front();
 907         }
 908 }
 909
 910 }