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Added Wave Function Collapse functionality
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| Original file line number | Diff line number | Diff line change |
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| // Copyright 2018 Wouter van Oortmerssen. All rights reserved. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
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| // Very simple tile based Wave Function Collapse ("Simple Tiled Model") implementation. | ||
| // See: https://github.com/mxgmn/WaveFunctionCollapse | ||
| // Derives adjacencies from an example rather than explicitly specified neighbors. | ||
| // Does not do any symmetries/rotations unless they're in the example. | ||
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| // Algorithm has a lot of similarities to A* in how its implemented. | ||
| // Uses bitmasks to store the set of possible tiles, which currently limits the number of | ||
| // unique tiles to 64. This restriction cool be lifted by using std::bitset instead. | ||
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| // In my testing, generates a 50x50 tile map in <1 msec. 58% of such maps are conflict free. | ||
| // At 100x100 that is 3 msec and 34%. | ||
| // At 200x200 that is 24 msec and 13% | ||
| // At 400x400 that is 205 msec and ~1% | ||
| // Algorithm may need to extended to flood more than 2 neighbor levels to make it suitable | ||
| // for really gigantic maps. | ||
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| // inmap & outmap must point to row-major 2D arrays of the given size. | ||
| // each in tile char must be in range 0..127, of which max 64 may actually be in use (may be | ||
| // sparse). | ||
| // Returns false if too many unique tiles in input. | ||
| template<typename T> bool WaveFunctionCollapse(const int2 &insize, const char **inmap, | ||
| const int2 &outsize, char **outmap, | ||
| RandomNumberGenerator<T> &rnd, | ||
| int &num_contradictions) { | ||
| num_contradictions = 0; | ||
| typedef uint64_t bitmask_t; | ||
| const auto nbits = sizeof(bitmask_t) * 8; | ||
| array<int, 256> tile_lookup; | ||
| tile_lookup.fill(-1); | ||
| struct Tile { bitmask_t sides[4] = {}; size_t freq = 0; char tidx = 0; }; | ||
| vector<Tile> tiles; | ||
| int2 neighbors[] = { { 0, 1 }, { 1, 0 }, { 0, -1 }, { -1, 0 } }; | ||
| // Collect unique tiles and their frequency of occurrence. | ||
| for (int iny = 0; iny < insize.y; iny++) { | ||
| for (int inx = 0; inx < insize.x; inx++) { | ||
| auto t = inmap[iny][inx]; | ||
| if (tile_lookup[t] < 0) { | ||
| // We use a bitmask_t mask for valid neighbors. | ||
| if (tiles.size() == nbits - 1) return false; | ||
| tile_lookup[t] = (int)tiles.size(); | ||
| tiles.push_back(Tile()); | ||
| } | ||
| auto &tile = tiles[tile_lookup[t]]; | ||
| tile.freq++; | ||
| tile.tidx = t; | ||
| } | ||
| } | ||
| // Construct valid neighbor bitmasks. | ||
| for (int iny = 0; iny < insize.y; iny++) { | ||
| for (int inx = 0; inx < insize.x; inx++) { | ||
| auto t = inmap[iny][inx]; | ||
| auto &tile = tiles[tile_lookup[t]]; | ||
| int ni = 0; | ||
| for (auto n : neighbors) { | ||
| auto p = (n + int2(inx, iny) + insize) % insize; | ||
| auto tn = inmap[p.y][p.x]; | ||
| assert(tile_lookup[tn] >= 0); | ||
| tile.sides[ni] |= 1 << tile_lookup[tn]; | ||
| ni++; | ||
| } | ||
| } | ||
| } | ||
| size_t most_common_tile_id = 0; | ||
| size_t most_common_tile_freq = 0; | ||
| for (auto &tile : tiles) if (tile.freq > most_common_tile_freq) { | ||
| most_common_tile_freq = tile.freq; | ||
| most_common_tile_id = &tile - &tiles[0]; | ||
| } | ||
| // Track an open list (much like A*) of next options, sorted by best candidate at the end. | ||
| list<pair<int2, int>> open, temp; | ||
| // Store a bitmask per output cell of remaining possible choices. | ||
| auto max_bitmask = (1 << tiles.size()) - 1; | ||
| enum class State : uchar { NEW, OPEN, CLOSED }; | ||
| struct Cell { | ||
| bitmask_t wf; | ||
| uchar popcnt = 0; | ||
| State state = State::NEW; | ||
| decltype(open)::iterator it; | ||
| Cell(bitmask_t wf, uchar popcnt) : wf(wf), popcnt(popcnt) {} | ||
| }; | ||
| vector<vector<Cell>> cells(outsize.y, vector<Cell>(outsize.x, Cell(max_bitmask, tiles.size()))); | ||
| auto start = rndivec<int, 2>(rnd, outsize); | ||
| open.push_back({ start, 0 }); // Start. | ||
| auto &scell = cells[start.y][start.x]; | ||
| scell.state = State::OPEN; | ||
| scell.it = open.begin(); | ||
| // Pick tiles until no more possible. | ||
| while (!open.empty()) { | ||
| // Simply picking the first list item results in the same chance of conflicts as | ||
| // random picks over equal options, but it is assumed the latter could generate more | ||
| // interesting maps. | ||
| size_t num_candidates = 1; | ||
| auto numopts_0 = cells[open.back().first.y][open.back().first.x].popcnt; | ||
| for (auto it = ++open.rbegin(); it != open.rend(); ++it) | ||
| if (numopts_0 == cells[it->first.y][it->first.x].popcnt && | ||
| open.back().second == it->second) | ||
| num_candidates++; | ||
| else | ||
| break; | ||
| auto candidate_i = rnd(num_candidates); | ||
| auto candidate_it = --open.end(); | ||
| for (int i = 0; i < candidate_i; i++) --candidate_it; | ||
| auto cur = candidate_it->first; | ||
| temp.splice(temp.end(), open, candidate_it); | ||
| auto &cell = cells[cur.y][cur.x]; | ||
| assert(cell.state == State::OPEN); | ||
| cell.state = State::CLOSED; | ||
| bool contradiction = !cell.popcnt; | ||
| if (contradiction) { | ||
| num_contradictions++; | ||
| // Rather than failing right here, fill in the whole map as best as possible just in | ||
| // case a map with bad tile neighbors is still useful to the caller. | ||
| // As a heuristic lets just use the most common tile, as that will likely have the | ||
| // most neighbor options. | ||
| cell.wf = 1 << most_common_tile_id; | ||
| cell.popcnt = 1; | ||
| } | ||
| // From our options, pick one randomly, weighted by frequency of tile occurrence. | ||
| // First find total frequency. | ||
| size_t total_freq = 0; | ||
| for (size_t i = 0; i < tiles.size(); i++) if (cell.wf & (1 << i)) total_freq += tiles[i].freq; | ||
| auto freqpick = rnd(total_freq); | ||
| // Now pick. | ||
| size_t picked = 0; | ||
| for (size_t i = 0; i < tiles.size(); i++) if (cell.wf & (1 << i)) { | ||
| picked = i; | ||
| if ((freqpick -= tiles[i].freq) <= 0) break; | ||
| } | ||
| assert(freqpick <= 0); | ||
| // Modify the picked tile. | ||
| auto &tile = tiles[picked]; | ||
| outmap[cur.y][cur.x] = tile.tidx; | ||
| cell.wf = 1 << picked; // Exactly one option remains. | ||
| cell.popcnt = 1; | ||
| // Now lets cycle thru neighbors, reduce their options (and maybe their neighbors options), | ||
| // and add them to the open list for next pick. | ||
| int ni = 0; | ||
| for (auto n : neighbors) { | ||
| auto p = (cur + n + outsize) % outsize; | ||
| auto &ncell = cells[p.y][p.x]; | ||
| if (ncell.state != State::CLOSED) { | ||
| ncell.wf &= tile.sides[ni]; // Reduce options. | ||
| ncell.popcnt = PopCount(ncell.wf); | ||
| int totalnnumopts = 0; | ||
| if (!contradiction) { | ||
| // Hardcoded second level of neighbors of neighbors, to reduce chance of | ||
| // contradiction. | ||
| // Only do this when our current tile isn't a contradiction, to avoid | ||
| // artificially shrinking options. | ||
| int nni = 0; | ||
| for (auto nn : neighbors) { | ||
| auto pnn = (p + nn + outsize) % outsize; | ||
| auto &nncell = cells[pnn.y][pnn.x]; | ||
| if (nncell.state != State::CLOSED) { | ||
| // Collect the superset of possible options. If we remove anything but | ||
| // these, we are guaranteed the direct neigbor always has a possible | ||
| //pick. | ||
| bitmask_t superopts = 0; | ||
| for (size_t i = 0; i < tiles.size(); i++) | ||
| if (ncell.wf & (1 << i)) | ||
| superopts |= tiles[i].sides[nni]; | ||
| nncell.wf &= superopts; | ||
| nncell.popcnt = PopCount(nncell.wf); | ||
| } | ||
| totalnnumopts += nncell.popcnt; | ||
| nni++; | ||
| } | ||
| } | ||
| if (ncell.state == State::OPEN) { | ||
| // Already in the open list, remove it for it to be re-added just in case | ||
| // its location is not optimal anymore. | ||
| totalnnumopts = min(totalnnumopts, ncell.it->second); | ||
| temp.splice(temp.end(), open, ncell.it); // Avoid alloc. | ||
| } | ||
| // Insert this neighbor, sorted by lowest possibilities. | ||
| // Use total possibilities of neighbors as a tie-breaker to avoid causing | ||
| // contradictions by needless surrounding of tiles. | ||
| decltype(open)::iterator dit = open.begin(); | ||
| for (auto it = open.rbegin(); it != open.rend(); ++it) { | ||
| auto onumopts = cells[it->first.y][it->first.x].popcnt; | ||
| if (onumopts > ncell.popcnt || | ||
| (onumopts == ncell.popcnt && it->second >= totalnnumopts)) { | ||
| dit = it.base(); | ||
| break; | ||
| } | ||
| } | ||
| if (temp.empty()) temp.push_back({}); | ||
| open.splice(dit, temp, ncell.it = temp.begin()); | ||
| *ncell.it = { p, totalnnumopts }; | ||
| ncell.state = State::OPEN; | ||
| } | ||
| ni++; | ||
| } | ||
| } | ||
| return true; | ||
| } |
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| @@ -0,0 +1,96 @@ | ||
| // Example of using Wave Function Collapse to generate gameworlds based on tiles. | ||
| // Using ascii chars here for simplicity. | ||
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| // Using """ string literals so we don't have to escape \ :( | ||
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| tilemap :== [ | ||
| """ /--\ """, | ||
| """ | | """, | ||
| """ | | """, | ||
| """/--J L--\ """, | ||
| """| | """, | ||
| """| | """, | ||
| """L--\ /--J """, | ||
| """ | | """, | ||
| """ | | """, | ||
| """ L--J """, | ||
| """ """, | ||
| ] | ||
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| benchmark :== false | ||
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| if benchmark: | ||
| no_conflicts := 0 | ||
| for(1000) i: | ||
| outmap, conflicts := wave_function_collapse(tilemap, xy { 100, 100 }) | ||
| print i + ": " + conflicts | ||
| if not conflicts: no_conflicts++ | ||
| print no_conflicts | ||
| print seconds_elapsed() | ||
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| else: | ||
| // Just print a single no-conflict example. | ||
| for(100) i: | ||
| outmap, conflicts := wave_function_collapse(tilemap, xy { 100, 50 }) | ||
| if not conflicts: | ||
| print "iteration: " + i | ||
| for(outmap) s: print s | ||
| return from program | ||
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| /* | ||
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| prints: | ||
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| | | /-\ /-------J | | L-J /--J | ||
| | /--J | | | | | | | ||
| | | | L-J | | /-\ | | ||
| -----------J /-J | | | /------------\ | | | / | ||
| | L-\ /----J | | | | | | | | ||
| | | | /--J | | | L----J | | ||
| | | L-\ | | | | | | ||
| ----\ | L-\ | | /-\ /-J | | L | ||
| | | | | | | | | L-------------\ | /---\ | ||
| | | | /-----J L-J L--J | L-\ | | | ||
| | | | | | | | | | ||
| | | | | /-------\ | | | | | ||
| | | | | | | | L----J | | ||
| | | /---------J L-----\ | /---J | | | ||
| /-J | | | /-----J | /-J /----J | ||
| | | | | /----\ | | | | | ||
| | | | /-\ /----J | | | | | | | ||
| | | | | | | | | | | | /------J | ||
| | | | | | /-J /--\ /-----J | | | | | | ||
| | L-J | | | | | | | | | /--J | | ||
| L-----\ | | | | L--J | L---\ | | | /--\ /----\ | ||
| | /---\ | | | | | | L------J | | | | | | ||
| | | | | | | | | | | | | | | | ||
| --\ | | L-----J | | | | | | | | | L-- | ||
| | | | | L--\ | /--------J | | | | /--J | ||
| --J /--J | /-\ | | | | | /--J | | | /----- | ||
| | L---\ | | | | | | | | | L---J | | ||
| | | | | | | | | | /----\ | | | | ||
| | L--J | | | | | /-\ | | | | | /----\ L----\ | ||
| | | | L-J | | | | | | | | | | | | ||
| L------------\ | | L-------J | | | | | | | | | | ||
| | | | | | | | | | | L--\ | | ||
| /-------------J | | /---\ | L------J | | | | | | | ||
| | /-J | | | /---J | | | | | | | ||
| | | L------\ | L---\ | | | | L--\ /--J | | ||
| | /-\ L-\ | | | | | L-----\ | | | | | ||
| | | | | | | | | /----\ | /-\ | L--\ | | | | ||
| --\ | | | | L---J | L--\ | | | | | | | | | L | ||
| | | | | | | | | /-J | L-J | | | | | ||
| L-J L-J L---------\ | | | | | /--J | | | | ||
| | L-\ | | | | | | | L---\ | ||
| ----\ /---\ | | L------J | | | | | | /-- | ||
| | | | | | | | L--\ | | | | | ||
| | L---J | /---J | | | L--J | | | ||
| | | /--\ | /--\ | | | | | | ||
| L------\ /-----J | | | | | | | /--J | | | ||
| | /--\ | | | | L--J | | | | | | ||
| | | | | | | | /-\ L-------\ | L----------\ | | | ||
| | | L---J | | | | | | | | L--J | ||
| | | | | | | | L-J | | ||
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| */ | ||
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