nx_state_delta_codec.nx

nx_state_delta_codec.nx -- quantized bit-packed entity state delta codec. Foundation for poor-internet multiplayer. The naive "serialize full entity state every frame" approach uses ~32 bytes/entity (x,y,z,yaw, pitch,health,id,flags as i64). At 60Hz x 100 entities = 192 KB/s. On a 56 kbps dial-up link (7 KB/s ceiling) that's 27x over budget. Delta-quantize-bitpack collapses this to typical 1-4 bytes per entity per frame: - Bit cursor over a byte buffer (write_bits / read_bits). - Signed N-bit delta encoding (twos-complement) for position + velocity changes between adjacent frames. - Unsigned N-bit absolute encoding for angles (256-step yaw = ~1.4 deg precision; the GGPO/Skullgirls choice). - Varint (7-bit continuation, identical wire format to Protobuf varint / LEB128) for sparse integer fields. Bandwidth budget on a typical FPS frame: per entity: 1 byte change-mask + ~3 bytes delta = 4 bytes 100 entities at 60Hz = 24 KB/s Compare: full-state baseline 192 KB/s -> 8x reduction. On 56 kbps dial-up, area-of-interest culling brings the entity count down to ~20 in-view -> 4.8 KB/s, fits under the 7 KB/s ceiling. Source references (all open): - GGPO bit-packed input frames (Cannon 2006, pond3r/ggpo) - Slither.io / Agar.io quantized state protocols (ClitherProject reverse-eng) - Protobuf varint / LEB128 (developers.google.com/protocol-buffers/docs/encoding) - Quake 3 delta-compressed entity protocol (Carmack .plan) genealogy_id: ggpo_bitpacked_inputs + protobuf_varint + quake3_delta_entities lineage_id: bandwidth_quantize_entity_state