nx_aoi_grid.nx

nx_aoi_grid.nx -- area-of-interest spatial grid for open-world culling. Per the Agar.io/Slither.io lesson (reverse-engineered protocols at ClitherProject + Diep.io / Krunker community wikis): the single biggest bandwidth saver for open-world multiplayer is to ONLY stream entities within the player's view radius. Naive "broadcast all entities to all players" scales as O(N^2) in players-times-entities; area-of-interest culling brings it to O(N * view_density). This primitive provides: - 2D cell-bucket grid over Q14-fixed-point world coordinates - insert / remove / query_radius operations - returns entity IDs within radius for a (player_x, player_z) query Use case: caller maintains an "entity table" keyed by entity ID; the grid is the spatial index that lets a per-player streamer ask "which entities should this player see?" 60 times per second. Bandwidth math (from genre-bench doc): Naive: 100 entities * 60 Hz * 30 B/entity = 180 KB/s -- 25x over the 7 KB/s dial-up ceiling. With AOI (20 in-view): 20 * 60 * 30 = 36 KB/s. Still over. With AOI + nx_state_delta_codec (4 B/entity typical): 20 * 60 * 4 = 4.8 KB/s. FITS UNDER 7 KB/s. Storage layout (i64 cells in flat block + raw bucket bytes): h[0] = cell_size_q14 (size of one cell side in Q14 metres) h[1] = grid_dim (cells per axis; total cells = grid_dim^2) h[2] = origin_x_q14 (world coord of cell (0,0) lower edge) h[3] = origin_z_q14 h[4] = bucket_capacity (max entities per cell) h[5] = bucket_storage (i64 ptr; layout below) Per cell layout (i64 cells): [0] = count of entities in cell [1..1+3*cap] = (id, x_q14, z_q14) triples Cell stride = 1 + 3 * bucket_capacity. Source references (open): - Slither.io protocol: ClitherProject/Slither.io-Protocol (GitHub)