claude
005679f1b5
(1) Bullets appeared to trail the ship. Two independent causes, measured with
the new tools/diag_prediction.gd rather than guessed at:
- ServerRuntime ticked before ClientRuntime, so input sampled on frame N was
not consumed until frame N+1, leaving the drawn ship a constant one tick
(4.00px at 240 u/s) ahead of the authoritative one that bullets spawn from.
ClientRuntime now sets process_physics_priority = -10. Gap on a listen
server: 4.00px -> 0.10px mean, 0.30px worst.
- PLAYER_MUZZLE_OFFSET was PLAYER_RADIUS + 6 = 12px against a 13px drawn
ship, so bullets were born inside the sprite. Regression from the previous
commit's hitbox shrink; it now derives from PLAYER_VISUAL_RADIUS.
(2) No more timed respawn. A downed player stays down until they ask for the
hub (E), which is an ordinary input -- the server has no "revive me" message.
(3) Escape channel 3s -> 1s, and damage no longer cancels it. An interruptible
channel makes killing the process strictly better than using the button, so a
dropped connection now runs the same channel: the player stays in the world as
linkdead, still killable, and is only released once it completes. Instances
refuse to close while a linkdead body is resolving, or a solo drop would delete
it on the next tick and hand the exploit straight back.
(4) Escape opens an in-game menu: return to hub (routed through the same held-
escape channel, not a new message), disconnect, quit.
(5) Server pushes a roster so the hub shows who is online and which dungeon
they are in. Entering a dungeon grants 2s arrival protection -- invulnerable
AND weapons-cold, since invulnerability alone would make the spawn a free
firing position -- flagged in the snapshot and drawn on every protected ship.
(6) Cleared dungeons hold the party 30s (was 5s) with a visible countdown.
(7) The hub's grey circle was a 100k-HP target dummy that read as scenery. Now
drawn as a bullseye so its purpose is legible.
Protocol version 1 -> 2. 91 tests (was 78); smoke.sh gains a bot that is
SIGKILLed mid-dungeon to prove the disconnect path end to end. check.sh,
test.sh and smoke.sh all pass.
136 lines
6.9 KiB
Markdown
136 lines
6.9 KiB
Markdown
# Transcience
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Top-down twin-stick bullet-hell with a dedicated, server-authoritative backend.
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Godot 4.7, GDScript only. One executable is both server and client.
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## Commands
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```bash
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tools/check.sh # parse-check every script (~5s) -- run after every edit
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tools/test.sh # GUT suite, headless (~2s)
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tools/smoke.sh # real server + 2 bot clients over ENet (~35s)
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tools/bench.gd # godot --headless --path . --script tools/bench.gd
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tools/server.sh # dedicated server
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tools/client.sh --join --name ada
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```
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Everything after `--` goes to `GameOpts.parse()`:
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| Flag | Effect |
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| --- | --- |
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| `--server` | Dedicated server, no view. |
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| `--join` | Skip the menu and connect. |
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| `--listen` | Skip the menu and host a listen server with a local player. |
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| `--bot` | Scripted input instead of the keyboard. Implies `--join`. |
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| `--host`, `--port`, `--name` | Connection details. |
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| `--autoquit N` | Quit after N physics ticks. |
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| `--boss-rush` | Server-side: new dungeons open straight onto the boss. |
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| `--verbose` / `--quiet` | Log level. |
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A change is done when `check.sh`, `test.sh` and — if it touched networking,
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instances or the simulation — `smoke.sh` all pass. Say so explicitly; do not
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report a networking change as working on the strength of unit tests alone.
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## Hooks
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`tools/install-hooks.sh` once per clone (points `core.hooksPath` at
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`.githooks/`, committed in the repo — plain bash, no `pre-commit` framework, so
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cloning costs nothing extra to run tools/*.sh). Own `.gd` files (not vendored
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`addons/`) trigger `check.sh` + `test.sh` on commit (~7s); `smoke.sh` runs on
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push (~35s, skip deliberately with `SKIP_SMOKE_HOOK=1 git push`).
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## The one rule
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**The server decides everything; the client only sends intent.**
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A client can send exactly two things: an [InputFrame] (move vector, aim angle,
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three button bits) and a handshake. There is no message for "I moved here", "I
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hit that", "I took damage" or "my escape finished". Adding one would collapse
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the whole security model, so don't — validate-after-the-fact is strictly weaker
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than having no code path at all.
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`SimWorld.authoritative` is `true` on the server and `false` on the client. In
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replica mode the world runs no AI, fires no emitters and resolves no hits; it
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only integrates bullets it was told about. `tests/unit/test_server_authority.gd`
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and `tests/integration/test_replica_parity.gd` pin this down.
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## Layout
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| Path | What lives there |
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| --- | --- |
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| `src/sim/` | The whole game as plain RefCounted objects. No nodes, no physics server, no rendering. |
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| `src/sim/patterns/` | Bullet emitters — the authoring surface for every enemy and boss. |
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| `src/content/content.gd` | All enemies and bosses, defined in code. Source of truth. |
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| `src/net/` | Codec, `ServerRuntime`, `ClientRuntime`. |
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| `src/instances/` | Lobby hub and dungeon runs. |
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| `src/view/`, `src/ui/` | Read-only rendering. Never decides anything. |
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| `src/autoload/net.gd` | The only autoload. RPC surface. |
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| `tools/` | Headless tooling. |
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The simulation must not import anything from `src/net/`, `src/view/` or
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`src/ui/`, and must not touch `Net`. That is what lets tests drive a thousand
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ticks in milliseconds with no SceneTree.
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## Godot gotchas that will waste your time
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1. **New `class_name` needs a cache refresh.** `.godot/global_script_class_cache.cfg`
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is only rebuilt by the editor or `godot --headless --path . --import`.
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Until then every use of the new class reports `Identifier not declared`,
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which looks like a real error. `check.sh` does the refresh for you.
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2. **Autoload names do not resolve under `--script`.** A `--script` run has no
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main loop, so `Net` is `Identifier not found`. Tools that need autoloads must
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run as a scene (see `tools/check.tscn`); tools that don't can use `--script`.
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This is why `GameLog` and `GameOpts` are static classes rather than autoloads.
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3. **`ResourceLoader.load()` returns non-null for a broken script.** Never test
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the return value to detect a parse error; read the engine's stderr instead.
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And never call `Script.reload()` on the script you are running — it hangs.
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4. **Input events default to `device = 16`, which matches nothing.** Bindings
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must use `device = -1`. `tools/setup_input_map.gd` generates the input map
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correctly; edit that file, not the `[input]` block in `project.godot`.
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5. **`set_anchors_preset(preset)` does not zero the offsets.** `keep_offsets`
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defaults to `false`, which despite the name means "recompute offsets to keep
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the control's *current* rect on screen" — for a freshly created Control that
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rect is `(0,0)`-sized, so it comes out pinned to the top-left corner
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regardless of the anchors. Use `set_anchors_and_offsets_preset()` for any
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Control built in code. Separately: `.position` assigns an *absolute*
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coordinate even on an anchored control; `offset_left`/`offset_top` are the
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anchor-relative ones. This combination silently broke the main menu and
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three pieces of the HUD.
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6. **`ProjectSettings.save()` drops settings equal to the engine default** and
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strips comments. Anything load-bearing (the 60 Hz tick) is asserted in code
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in `src/main.gd` instead of trusted to `project.godot`.
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## Non-obvious invariants
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- **`ClientRuntime.process_physics_priority = -10`.** The client must sample and
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send input before `ServerRuntime` ticks, or a listen server's drawn ship sits
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a permanent tick ahead of the authoritative one and bullets trail it. Measure
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with `godot --headless --path . res://tools/diag_prediction.tscn` (~0.1px is
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healthy, 4px means the ordering broke).
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- **`PLAYER_RADIUS` (hitbox) < `PLAYER_VISUAL_RADIUS` (sprite), and
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`PLAYER_MUZZLE_OFFSET` derives from the visual one.** Prefer a visible
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near-miss over an invisible hit; keep the muzzle clear of the sprite.
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- **A disconnect is not an exit.** Dropping in a dungeon keeps the player in the
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world as `linkdead`, channelling out over the same second the escape costs.
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Damage must never cancel the escape channel, or quitting beats the button.
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See [docs/NETCODE.md](docs/NETCODE.md).
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## Adding content
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A new enemy or boss is data, never code. Add a builder to
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`src/content/content.gd` returning an `EnemyDef` / `BossDef` made of the
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emitters in `src/sim/patterns/`, register its id in `enemy()` / `boss()`, and
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add a test. `tests/unit/test_boss.gd::test_a_brand_new_boss_needs_no_engine_changes`
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builds a boss from scratch and asserts the simulation needs no changes to run
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it — if you find yourself adding a per-boss branch to `SimWorld`, stop and add
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an emitter type instead.
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`tools/export_content.gd` writes `.tres` copies into `resources/` for tuning in
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the editor inspector. Those are an export, not the source; port changes back.
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## Style
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Typed GDScript everywhere (`untyped_declaration` is a warning). Tabs, snake_case
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files, `PascalCase` class names. Comments explain *why* a thing is the way it is —
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the netcode and anti-cheat decisions especially. Keep the existing density.
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