ASCENDANT — 3D arena fighter with rollback netcode - #18

A browser 3D arena fighter, added under ascendant/ as a self-contained subproject. It shares no code with the battle royale at the repo root.

This is a mirror. The project is intended to live in its own repository — it is here so the work is not stranded while cloudygetty-ai/ascendant does not yet exist.

What it is

Three lineages fused:

• Street Fighter 6 — Drive gauge (Impact, Parry, Rush, Overdrive), real frame data with startup/active/recovery, cancel chains, counter hits, and Burnout when the gauge empties
• Mortal Kombat — best-of-three rounds, Fatal Blow once per match below 30% health, and the finisher
• Dragon Ball — flight, a ki economy whose only fast source is a defenceless charge stance, Vanish to escape a combo, contested beam clashes, and Ascension

The finisher

A match-ending blow does not kill. It leaves the loser standing and swaying while the announcer calls PUT HER UNDER. — the pronoun resolves from the loser's own character sheet, so HER, HIM or THEM. The winner then has 200 frames to land that character's named Erasure; let the window lapse and the match simply ends.

Architecture

ascendant/src/
├── engine/    pure simulation — no DOM, no three.js, no network
├── net/       rollback session, protocol, transports
├── render/    three.js scene, procedural rigs, poses, VFX, camera
├── ui/        HUD, menus, styles
└── client/    input mapping, fixed-timestep loop, bootstrap
ascendant/server/   WebSocket relay + lobby

Dependencies flow one way and a lint rule enforces it: the engine may not import from render, ui, net, client, or three.

Determinism

step(state, inputs, config) is pure — same state plus same inputs always produces the same next state, on every machine. That drove three constraints inside the engine:

• Math.sin, Math.cos and Math.atan2 are banned. IEEE-754 exactly specifies + - * / and sqrt, but the transcendental functions are implementation-defined and drift between engines and CPUs. One ULP in a facing angle desyncs a match within seconds, so engine/math/trig.ts provides polynomial replacements.
• Math.random is banned — a seeded xorshift128 lives in the state and is snapshot and restored with it.
• No clocks.

checksum() hashes floats by exact bit pattern, so a one-ULP divergence is caught on the frame it happens.

Netcode

Local input applies immediately; the opponent's is predicted by repeating their last input, then corrected by rewind and resimulation when the real input contradicts it. The server is a relay that pairs players and forwards inputs — it never simulates, so it can never be the thing that desyncs a match.

Verification

The decisive test: a peer running six frames of network delay lands on byte-identical state to a peer with none.

Notes for review

• CI at the repo root does not cover ascendant/; its own workflow config ships in ascendant/.github/workflows/ci.yml and will only take effect once the project moves to its own repo.
• The roster, stats and frame data are a coherent first pass, not a balanced game. Nothing has been playtested by a human — Helios's 130-damage solarFang and Korvath's armor are the kind of numbers only real matches expose.

🤖 Generated with Claude Code

https://claude.ai/code/session_017sxuEsAktMLBju5wmvGut8

Generated by Claude Code