A second Mac joins a hosted game by address and sees the host's player walk #29

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agra merged 2 commits from task/3992-a-second-mac-joins-a-hosted-game-by-addr into master

2026-10-31 11:09:36 +02:00

agra commented

2026-10-31 10:49:00 +02:00

Owner

Tracker: #3992

Step 1 of the multiplayer netcode plan (#3571): the app hosts a game over UDP, or joins one by address, and every player sees the others' skeletons walk, turn and jump where the server has them.

Transport. One non-blocking UDP socket a side (src/net/udp.sx). A message longer than a 1200-byte datagram crosses in fragments the receiver reassembles, and one missing a fragment is dropped whole (src/net/fragments.sx); the first map's whole snapshot crosses in two. The loopback (src/net/loopback.sx) is now an in-process datagram network behind the same send and receive, the tests' transport.
Handshake. connect (protocol version, the world file's hash, a client salt), challenge (a server salt), accept (both salts), welcome (player id, first snapshot). Nothing larger than the connect answers an address before the challenge round trip; a differing version or world is refused. 10 s of silence or a leave ends a connection and removes its player; a datagram that does not decode, or comes from an address with no connection, is dropped and the server carries on.
Many players. The game (src/sim/game.sx) is the server's rules and state apart from any transport; the server (src/sim/server.sx) runs it for every connection, each its own player joining at the map's first spawn marker, while a respawn takes the next marker in turn. Commands stay newest-wins per player; players pass through each other.
Hosting. The app's server ticks on its own thread over its own world read from the world file (src/sim/host.sx), and the host's own client joins it over UDP at 127.0.0.1 like any other. Launching hosts on UDP port 27960, --port sets another, --join <address>[:port] joins instead (src/net/launch.sx). A joined app whose server falls silent for 10 s closes, printing why. The in-frame lockstep of server and client is gone.
View. The client draws its eye, the bodies and the other players at a view tick that runs at the clock's pace two ticks behind the newest snapshot, leaning toward that delay, so the view moves forward every frame of a steady walk whatever phase of the client's ticks the snapshots arrive at (tests/sim_view.sx, which fails on the two-newest lerp by the client's own fraction).
Remote players draw as the training dummies' skeleton standing in the template's pose at their feet, turned to their yaw, and not while dead (tests/figure_draws.sx, with its golden).
Tests. Over UDP on 127.0.0.1 a server and two clients on the first map: each welcomed with its own player at the first spawn marker, each client's snapshot putting the other's player where the server's tick did (tests/net_udp.sx); a threaded host and two UDP clients (tests/net_host.sx); the handshake from both sides (tests/net_handshake.sx, tests/net_joining.sx); fragments (tests/net_fragments.sx). tests/sim_headless.sx covers the transport, server and host modules.
README, Playing: how to host and join.

Tracker: [#3992](https://sak.swipelab.com/tasks/3992) Step 1 of the multiplayer netcode plan (#3571): the app hosts a game over UDP, or joins one by address, and every player sees the others' skeletons walk, turn and jump where the server has them. - **Transport.** One non-blocking UDP socket a side (`src/net/udp.sx`). A message longer than a 1200-byte datagram crosses in fragments the receiver reassembles, and one missing a fragment is dropped whole (`src/net/fragments.sx`); the first map's whole snapshot crosses in two. The loopback (`src/net/loopback.sx`) is now an in-process datagram network behind the same send and receive, the tests' transport. - **Handshake.** connect (protocol version, the world file's hash, a client salt), challenge (a server salt), accept (both salts), welcome (player id, first snapshot). Nothing larger than the connect answers an address before the challenge round trip; a differing version or world is refused. 10 s of silence or a leave ends a connection and removes its player; a datagram that does not decode, or comes from an address with no connection, is dropped and the server carries on. - **Many players.** The game (`src/sim/game.sx`) is the server's rules and state apart from any transport; the server (`src/sim/server.sx`) runs it for every connection, each its own player joining at the map's first spawn marker, while a respawn takes the next marker in turn. Commands stay newest-wins per player; players pass through each other. - **Hosting.** The app's server ticks on its own thread over its own world read from the world file (`src/sim/host.sx`), and the host's own client joins it over UDP at 127.0.0.1 like any other. Launching hosts on UDP port 27960, `--port` sets another, `--join <address>[:port]` joins instead (`src/net/launch.sx`). A joined app whose server falls silent for 10 s closes, printing why. The in-frame lockstep of server and client is gone. - **View.** The client draws its eye, the bodies and the other players at a view tick that runs at the clock's pace two ticks behind the newest snapshot, leaning toward that delay, so the view moves forward every frame of a steady walk whatever phase of the client's ticks the snapshots arrive at (`tests/sim_view.sx`, which fails on the two-newest lerp by the client's own fraction). - **Remote players** draw as the training dummies' skeleton standing in the template's pose at their feet, turned to their yaw, and not while dead (`tests/figure_draws.sx`, with its golden). - **Tests.** Over UDP on 127.0.0.1 a server and two clients on the first map: each welcomed with its own player at the first spawn marker, each client's snapshot putting the other's player where the server's tick did (`tests/net_udp.sx`); a threaded host and two UDP clients (`tests/net_host.sx`); the handshake from both sides (`tests/net_handshake.sx`, `tests/net_joining.sx`); fragments (`tests/net_fragments.sx`). `tests/sim_headless.sx` covers the transport, server and host modules. - README, Playing: how to host and join.

agra added 1 commit

2026-10-31 10:49:00 +02:00

A second Mac joins a hosted game by address over UDP and sees the other players walk 2f0a3e5fa5

The app hosts a game on its own server thread, or joins one with --join.
Messages cross in fragments of at most 1200-byte datagrams, a client is
challenged before it is welcomed, the server serves a player for each
connection, and the client draws its eye, the bodies and the other players'
skeletons at a view that runs a steady delay behind the newest snapshot.

agra added 1 commit

2026-10-31 10:53:57 +02:00

The view keeps its delay behind the newest snapshot while the server's clock runs 1% apart from the client's 60c1ef28cc

agra merged commit 83f85faa34 into master

2026-10-31 11:09:36 +02:00

agra referenced this pull request from a commit

2026-10-31 11:09:37 +02:00

Merge pull request 'A second Mac joins a hosted game by address and sees the host's player walk' (#29) from task/3992-a-second-mac-joins-a-hosted-game-by-addr into master