ludic.nav (23.5b): a baked mesh resident by chunk

nav_load_index indexes a saved mesh's tiles (cell, offset, size, ref) from their headers and keeps the file open, with no tile in. nav_tiles_keep reads in the tiles within rin of any player and removes those past rout of all; the file is read through Ludic's pack-aware file_open. The file format is unchanged. tiles_test: tiles come and go with the point, a path works across the seams once they are in, and a reset closes all. Measured on the baked maps (the 900 / 1100 m ring round the start): Maroon 617 of 1807 tiles in, 8.9 MB instead of about 27 MB for a person and 5.4 MB of about 14 for a large walker; Lamar 391 of 1147. Both libraries are rebuilt; nav 17/17 on the Mac and the PC, DLL KERNEL32 only.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/ludic.nav/native/shim/nav_resident.inl

@@ -0,0 +1,72 @@
+// nav_resident.inl - a baked mesh whose tiles are resident by chunk (phase 23.5b): the file is
+// indexed once (each tile's grid cell, where its bytes are, its ref), and a tile's bytes are read
+// in when a player comes near and let go when all are far. The game reads the file (its reads are
+// the pack's); the shim only parses what it is handed and keeps the index.
+
+// a mesh with no tiles yet, from nav_save's 40-byte head; null for anything else
+NAV_SHIM void *nav_index_open(const unsigned char *head) {
+  int magic = 0, version = 0;
+  memcpy(&magic, head, 4); memcpy(&version, head + 4, 4);
+  if (magic != NAV_MAGIC || version != NAV_VERSION) return nullptr;
+  dtNavMeshParams p;
+  memset(&p, 0, sizeof(p));
+  memcpy(p.orig, head + 12, 12); memcpy(&p.tileWidth, head + 24, 4); memcpy(&p.tileHeight, head + 28, 4);
+  memcpy(&p.maxTiles, head + 32, 4); memcpy(&p.maxPolys, head + 36, 4);
+  dtNavMesh *mesh = dtAllocNavMesh();
+  if (!mesh || dtStatusFailed(mesh->init(&p))) { dtFreeNavMesh(mesh); return nullptr; }
+  return nav_open(mesh);
+}
+// how many tiles the file said it holds (from the same head)
+NAV_SHIM int nav_index_count_in(const unsigned char *head) {
+  int count = 0;
+  memcpy(&count, head + 8, 4);
+  return count;
+}
+
+// one tile's record, read at `offset`: its ref and size, and the start of its data (its header's
+// magic, version, x, y). Returns the data's size, so the caller can seek past it; -1 when not a tile
+NAV_SHIM int nav_index_put(void *h, const unsigned char *rec, long long offset) {
+  Nav *n = static_cast<Nav *>(h);
+  NavTileRec t;
+  memcpy(&t.ref, rec, 8); memcpy(&t.size, rec + 8, 4);
+  int magic = 0;
+  memcpy(&magic, rec + 12, 4); memcpy(&t.x, rec + 20, 4); memcpy(&t.y, rec + 24, 4);
+  if (magic != DT_NAVMESH_MAGIC || t.size <= 0) return -1;
+  t.offset = offset + 12;
+  n->tiles.push_back(t);
+  return t.size;
+}
+NAV_SHIM int nav_index_count(void *h) { return static_cast<int>(static_cast<Nav *>(h)->tiles.size()); }
+
+// tile i's centre and whether it is in: out[0] x, out[1] z, out[2] 1 in / 0 out, out[3] its bytes
+NAV_SHIM int nav_index_tile(void *h, int i, float *out) {
+  Nav *n = static_cast<Nav *>(h);
+  if (i < 0 || i >= (int)n->tiles.size()) return 0;
+  const NavTileRec &t = n->tiles[i];
+  const dtNavMeshParams *p = n->mesh->getParams();
+  out[0] = p->orig[0] + (t.x + 0.5f) * p->tileWidth;
+  out[1] = p->orig[2] + (t.y + 0.5f) * p->tileHeight;
+  out[2] = t.in ? 1.0f : 0.0f;
+  out[3] = (float)t.size;
+  return 1;
+}
+// where tile i's bytes are in the file (the caller seeks there and reads nav_index_size of them)
+NAV_SHIM long long nav_index_offset(void *h, int i) { return static_cast<Nav *>(h)->tiles[i].offset; }
+NAV_SHIM int nav_index_size(void *h, int i) { return static_cast<Nav *>(h)->tiles[i].size; }
+
+// tile i's bytes (staged by nav_stage, owned from here on) added to the mesh; 0 when refused
+NAV_SHIM int nav_index_in(void *h, int i, unsigned char *data, int size) {
+  Nav *n = static_cast<Nav *>(h);
+  if (i < 0 || i >= (int)n->tiles.size() || n->tiles[i].in || !data) { free(data); return 0; }
+  if (dtStatusFailed(n->mesh->addTile(data, size, DT_TILE_FREE_DATA, (dtTileRef)n->tiles[i].ref, nullptr))) { free(data); return 0; }
+  n->tiles[i].in = true;
+  return 1;
+}
+// tile i let go, its bytes with it
+NAV_SHIM int nav_index_out(void *h, int i) {
+  Nav *n = static_cast<Nav *>(h);
+  if (i < 0 || i >= (int)n->tiles.size() || !n->tiles[i].in) return 0;
+  n->mesh->removeTile((dtTileRef)n->tiles[i].ref, nullptr, nullptr);
+  n->tiles[i].in = false;
+  return 1;
+}