Bevy FPS Foundation

A modular first-person game foundation and in-process editor built on Bevy 0.18 and Avian 0.6 physics.

The runtime game provides a high-fidelity PBR stack (HDR, procedural atmosphere + image-based lighting, cascaded shadows, SSAO, TAA, bloom, fog, ACES tonemapping) plus Hybrid Auto Solari raytraced indirect lighting where supported, and local input/presentation glue for a fixed-step kinematic FPS simulation. The editor provides dockable egui panels, a filtered scene hierarchy, click selection, transform gizmos, undo/redo, asset import/placement, native Bevy scene save/load, and BRP support for external tooling.

Requirements

• Rust (stable; pinned via rust-toolchain.toml)
• Git LFS for binary game/source assets: run git lfs install once, then git lfs pull after clone.
• A Vulkan-capable GPU + drivers (developed against an NVIDIA RTX 3080 Ti)
• Linux build deps for winit/wgpu (ALSA, udev, etc.) if not already present

Running

# Check everything
cargo fmt --check
cargo check --workspace
cargo clippy --workspace
cargo clippy -p game -p shared -p protocol -p sim -- -D warnings
cargo test -p game --lib
cargo test -p sim

# Runtime game
cargo run -p game
cargo run -p game --features dev

# In-engine editor
cargo run -p editor
cargo run -p editor --features dev

Hot reload (gameplay iteration)

--features dev turns on Bevy dynamic linking for faster rebuilds (recommended day-to-day).

Add --features hot-reload for in-process hot reload of game_hot (sim movement, player input/camera, world bootstrap). The editor process stays open; only gameplay system bodies swap when the dylib rebuilds.

Two-terminal workflow (hot reload):

# Terminal 1 — rebuild the hot dylib on save
cargo watch -w crates/game_hot -w crates/sim -x "build -p game_hot --features dylib"

# Terminal 2 — run the editor once
cargo run -p editor --features dev,hot-reload

Or use the VS Code task watch game_hot (hot reload) alongside run editor (dev fast-link) (enable the hot-reload feature on the editor run task when using dylib iteration).

Input	Action
Save game_hot / sim gameplay code	Dylib rebuilds; status bar shows building… then reloaded
Ctrl+Shift+R	Manual refresh (on_hot_reload bootstrap: camera FX, ambient light)

Safe to hot reload: system logic, movement tuning in code, input mapping.

Requires full editor restart: new/changed component fields, new components, plugin schedule changes, editor UI code.

Note: the workspace uses the mold linker via clang (see .cargo/config.toml) for fast link times.

Target Cache Cleanup

Cargo/Bevy debug artifacts can grow quickly. Use the workspace cleanup task before reaching for a full cargo clean:

Command	Effect
cargo clean-target	Dry run: prints reclaimable target/ cache.
cargo clean-target --apply	Safe cleanup: removes incremental and rust-analyzer flycheck cache.
cargo clean-target --include-artifacts --days 3 --apply	Deeper cleanup: also removes stale hashed deps, build, .fingerprint, and example artifacts older than 3 days. Cargo will rebuild anything still needed.

VS Code tasks: target cleanup (dry run) and target cleanup (safe apply).

Launch Troubleshooting

• The native game/editor windows force an opaque Wayland surface and opaque camera clears to avoid compositor alpha issues on mixed HDR/SDR desktops.
• If the window maps but appears transparent on Hyprland or another Wayland compositor, launch with BEVY_FPS_HDR=0 to force the SDR camera path while debugging monitor/compositor behavior.
• The workspace patches bevy_render locally so transient Linux swapchain acquire timeouts skip one frame instead of panicking in prepare_windows.
• Debug launch configs and run tasks set WGPU_VALIDATION=0 to quiet the known wgpu/Vulkan validation-layer warning VUID-StandaloneSpirv-MemorySemantics-10871. This only disables the Vulkan validation layer for those launches; Rust panics and application errors still surface normally.
• If CodeLLDB / mold fails with hundreds of undefined symbol linker errors, the incremental target/ cache is stale. Run the VS Code task clean build editor (dev) or cargo clean -p editor && cargo build -p editor --features dev, then launch Debug editor again. Use cargo run -p editor --features dev from the terminal if you need libbevy_dylib on LD_LIBRARY_PATH automatically.

Editor Controls

Input	Action
F5	Toggle Edit / Play in the same viewport
F6	While playing: pause / resume simulation (stay in Play mode)
F8	While playing: possess player / eject to editor camera
G	Toggle clean game-view overlay (hide editor widgets/proxies/gizmos)
Ctrl+G	Toggle viewport grid
F	Focus editor camera on selection
Ctrl+Shift+1 / Ctrl+Shift+2	Save / recall viewport camera bookmark
RMB + mouse	Editor camera look; cursor hides while held
RMB + W A S D	Editor camera fly
RMB + Q / E	Editor camera down / up
Mouse wheel	Dolly editor camera
MMB + mouse	Pan editor camera
Click authored object, actor root icon, or visualizer in viewport	Select source entity
Click empty viewport / Esc	Deselect
Delete / Backspace	Delete selection
Ctrl+D	Duplicate selection
Ctrl+Z / Ctrl+Shift+Z / Ctrl+Y	Undo / redo
F2 in Hierarchy	Rename selection
W / E / R	Translate / rotate / scale gizmo
X	Toggle world/local gizmo orientation
Viewport toolbar (sun / brush / box icons)	Shading: Lit, Unlit (albedo), Colliders (mesh off)
Viewport eye/options	Toggle actor root icon categories, adjust icon/gizmo size, and control colliders, lights, spawns, prefab/model anchors, and runtime player/camera visualizers
Tab in viewport	Cycle selection through overlapping objects at last click
Click Player visualizer in Edit mode	Select or create the authored PlayerSpawn (Player Start)
Select Project Sun	Inspect project default lighting; create a scene sun override
Asset Browser project/file views	Browse assets/, search/filter/sort, switch grid/list, expand model subassets with generated thumbnails, inspect staged import/material settings, drag assets/submeshes into the viewport
Asset Browser context/details actions	Apply textures/materials, regenerate thumbnails, reimport models, place assets/submeshes, or move file assets to assets/.trash/
Ctrl+P	Command palette; type to filter, use arrow keys to select, Enter to run (scene.reset_lighting, selection.group, selection.focus, selection.reset_transform, play commands)
F7	While paused in Play: advance one sim tick
Shift/Ctrl + click (Hierarchy)	Additive selection
Hierarchy context	Reparent to other selection / Unparent
File menu	New, Open, Save, Save As, Import Assets, Export Selection, Save Selection As Prefab, Recent Scenes
Inspector component card	Collapse with caret, toggle active with status dot, or use triple-dot menu for reset/copy/paste/move/remove actions
Inspector footer → Add Component	Expands an inline search shelf for registered authoring, rendering, physics, gameplay, and volume components with descriptions, availability hints, and undo
Edit → Project Settings…	Edit assets/project.ron (rendering, physics, input)

Viewport shortcut keys require the pointer to be in the viewport and are suspended while typing in egui text fields or actively using camera navigation. Delete, Backspace, duplicate, and undo/redo also defer to text-field focus.

Play Mode

• Press F5 (or Play menu) to run the real game in-process: same GamePlugin, player, fixed-step sim, and rendering stack as the standalone game binary.
• The unified Viewport stays in place on play enter. The editor fly camera and player camera render to the same offscreen HDR texture depending on Edit/Play possession state.
• While editing, gameplay simulation and input are disabled (SimEnabled / GameInputEnabled). Entering Play enables simulation; F6 pauses/resumes the sim without leaving Play; F8 toggles possess (player input + camera) vs eject (editor fly camera while sim keeps running).
• Transport controls (Play, Pause, Stop, Eject) live on the main toolbar below the menu bar.
• The viewport uses the full project rendering stack from assets/project.ron (Edit → Project Settings…). Only one 3D camera carries that stack at a time (editor fly cam while editing/ejected, player cam while possessed) so GPU bind limits are respected.
• Add a PlayerSpawn marker component (via Inspector) on a level object to choose where Play starts; otherwise the default game spawn (0, 1.5, 10) is used.
• Actor root icons draw over scene meshes, stay screen-sized while zooming, and are prioritized when clicked.
• Clean game-view overlay (G) hides editor widgets, actor root icons, visualizers, selectable proxies, gizmos, selection outlines, and grid without changing the active camera.
• F5 stops Play and restores player sim state only; authored scene edits made during PIE are kept. Esc frees the cursor mid-play.

Game Controls

Input	Action
W A S D	Move
Mouse	Look
Space	Jump (coyote-time + buffered)
Left Shift	Sprint
Left Ctrl	Crouch
Esc	Release / re-grab mouse cursor

Scene Workflow

• Levels are saved as native Bevy dynamic scenes under assets/levels/.
• Editable entities use reflectable authoring components from crates/shared.
• The editable player start is an authored PlayerSpawn; moving it with the transform gizmo changes where Play mode boots the runtime player.
• Project settings provide default ambient/sun lighting. A scene-authored directional LightDesc acts as a per-scene sun override and disables the project sun contribution.
• Hydration systems turn authoring data into runtime meshes, GLTF scenes, materials, lights, and Avian colliders. Persisted ActorId / ComponentInstanceId values are stable; raw Bevy Entity IDs are runtime-only.
• Inspector component active toggles are saved in InspectorOrder. Inactive authoring components keep their data but do not hydrate runtime meshes, lights, physics, or post-process effects.
• Dragging glTF/GLB/FBX assets creates StaticMeshRenderer actors by default from normalized artifacts in assets/meshes/generated/. Renderer slots reference imported content-browser mesh and material assets, while generated collision is stored separately in ColliderDesc plus RigidBodyDesc. Switch a model asset's placement mode to Scene Instance in Asset Browser details when you need full SceneRoot loading for animation/skinning/scene data. Expanding a model in the Asset Browser exposes normalized mesh/material/texture subassets; dragging a mesh subasset places that part through the same static mesh renderer path.
• Runtime-only handles/colliders are not serialized directly, keeping scenes stable and portable.
• Editor-only cameras and helper roots are filtered from selection, hierarchy, and scene save.
• PIE restores player sim only (transform, velocity, jump state) when you stop Play; authored LevelObject edits made during PIE remain in the scene (the level may show as dirty).
• Play mode swaps the unified viewport between the player camera (possessed) and editor fly camera (ejected).
• Gameplay movement runs in a fixed timestep in crates/sim. Raw keyboard/mouse input is translated by crates/game into protocol::PlayerInputIntent before it mutates simulation state.

Troubleshooting

Viewport is black or wireframe-only

1. Check the mode badge (bottom-right of the viewport). Collider hides meshes — click the sun toolbar icon for Lit shading.
2. Window → Rendering → Active Camera: check Runtime lights (directional/point/spot counts), scene vs project sun status, and contributing post-process volumes. Scene directionals override the project sun; use Scene → Lighting → Use project sun to restore project defaults.
3. Solari requested but not visually changing: check Window → Rendering → Active Camera for requested/effective GI, fallback reason, tagged meshes, Solari-compatible mesh assets, render instances, bind-group readiness, and compatible lights. Effective Solari forces an HDR camera target because Bevy Solari writes through a storage texture; imported/custom meshes need TriangleList geometry, POSITION/NORMAL/UV_0/TANGENT attributes, and U32 indices for Bevy 0.18 Solari.
4. Lighting changes do nothing in Solari: Bevy 0.18 Solari samples directional lights and emissive meshes, not point/spot lights. Use Directional lights or emissive materials in Solari; switch to Forward PBR for point/spot light authoring.
5. GiMode Auto shows Forward: Solari RT wgpu features are unavailable on this GPU. Dev RT override: BEVY_FPS_FORCE_SOLARI=1.
6. Volume overrides ignored: confirm camera is inside volume AABB; check priority in Rendering → Volumes tab.
7. Custom post FX: RON under assets/post_fx/; assign path in volume inspector (see docs/editor/rendering.md).
8. Scene Open / Recent runs hydration immediately; zero runtime lights after load usually means missing LightDesc on light actors (see Rendering panel).

Hierarchy sort jumps when clicking

Sort: Name / Type now use stable tie-breakers (duplicate names like several Pillar rows stay put). Use Sort: Manual and drag-and-drop for explicit sibling order.

Hierarchy scrolls during drag

Scroll-to-drag is disabled while dragging actors. Release the mouse to finish or cancel the drag.

Cursor / VSCode Setup

The .vscode/ folder is preconfigured:

• extensions.json recommends rust-analyzer, Even Better TOML, CodeLLDB, crates, and Error Lens.
• settings.json runs clippy on save, enables proc-macro/build-script support, formats on save, and excludes target/ from search/watch.
• tasks.json provides workspace check/clippy plus game/editor build/run tasks.
• launch.json provides CodeLLDB launch configs for the editor and game.
• .github/workflows/ci.yml mirrors local formatting, check, clippy, test, and binary build verification.

Architecture Decisions

• Documentation index
• Mission — editor framework & principles
• Editor framework docs
• ADR 0001: Roadmap Architecture
• ADR 0002: Bevy Version And Migration Policy
• ADR 0003: Editor Framework Mission
• ADR 0014: Unified Viewport Model
• ADR 0016: Unified Rendering Contract
• ADR 0017: Normalized Static Mesh Assets

Project Layout

crates/
  protocol/        Shared tick, input intent, command, and message/event protocol types
  sim/             Fixed-step gameplay simulation and determinism test scaffolding
  shared/          Reflectable authoring components + hydration systems
  game/            Runtime FPS game library + standalone game binary
  editor/          In-process egui editor binary

Implementation Checklist

• Workspace: game, shared, editor, protocol, sim
• Shared authoring components + hydration
• Protocol tick, input intent, command, and basic message/event types
• Fixed-step deterministic sim crate for player movement/controller state
• Runtime game refactored into GamePlugin
• Raw game input translated into protocol intent before simulation
• Docked egui editor scaffold
• Editor fly camera
• Mesh picking selection + highlights
• Transform gizmos
• Editor-side scene visualizers for colliders, lights, player spawns, prefab/model anchors, and runtime player/cameras
• Selectable, screen-sized actor root icons in the 3D viewport with per-category visibility controls
• Filtered hierarchy, inspector, viewport, toolbar, asset browser, and status panels
• Delete, duplicate, rename, and structural/material undo-redo
• Native Bevy scene New/Open/Save/Save As with dirty title tracking
• Asset import, static mesh/prefab placement, texture assignment, and selection export
• PIE player-only snapshot/restore (authored LevelObject edits persist on stop)
• Unified viewport render-to-texture target + Play session bootstrap
• PlayerSpawn authoring marker for editor Play start location
• BRP enabled in the editor
• Cursor/VSCode workspace tasks + launch configs
• Opaque Wayland window launch defaults + SDR/HDR runtime toggle
• CI workflow for format, check, clippy, tests, and binary builds
• ADRs for roadmap architecture and Bevy migration policy
• Determinism harness: same inputs over same ticks produce the same state summary/hash
• Verify: cargo fmt --check / cargo check --workspace / cargo clippy --workspace / strict foundation clippy / cargo test -p sim
• Stable asset registry with UUIDs + import settings in asset browser details
• Asset Browser expandable model subasset shelves, independent mesh/material/texture thumbnails, staged import/material details with shader-schema parameters, context actions, and trash-first file removal
• Prefab instances (PrefabInstance) + save-as-prefab + unpack
• Unsaved-scene confirm on New/Open/Recent
• Hierarchy multi-select, reparent undo, multi-entity gizmo transform
• Typed inspector undo (light, rigid body, collider, primitive, material, static mesh renderer) + registry-driven Add Component footer
• Gameplay authoring markers + visualizers (WeaponSpawn, TriggerVolume, etc.)
• Command palette execution; PIE sim step (F7); xtask validate-levels
• ADRs 0005–0012 (prefab/registry, scene schema, EditorPlugin, editor structure, authoring/hydration, ActorKind, sun policy, zero-debt)
• ActorInspectorSection registry + game demo section (game::editor_ext)
• Command palette: reset lighting, group selection, focus selection
• CI: cargo test -p shared, scene authoring-only check on repo level, cargo check -p editor --features dev
• scene crate schema stamp/migrate/validate on save/load + CI validate-levels
• Project Settings draft + Apply (HDR/swapchain safe); File → Project New/Open
• Editor lib/bin split + EditorPluginGroup; game EditorPlugin dogfood panel
• FBX/glTF model import + normalized StaticMeshRenderer placement; explicit scene-instance load via bevy_ufbx / ModelRef
• Asset browser model thumbnails (unified assets/thumbnails/ pipeline; ThumbnailState cache; FBX via FbxThumbnailSource)
• Material assets (assets/materials/*.ron, inspector picker, drag-drop to selection)
• Prefab instance overrides v2 (transform/material/child visibility apply-revert groups)
• Advanced rendering: GiMode, post-process volumes, Rendering panel, requested/effective render stack, Solari integration, emissive materials, post FX assets (ADR 0013, ADR 0016, rendering guide)
• Static mesh renderer component, generated normalized mesh artifacts, source/one-actor hierarchy placement, and inspector renderer slots (ADR 0017)
• Componentized actor inspector, unified component cards, thumbnail static mesh slots, imported asset Browse/Locate/Clear refs with inherited source defaults, collider split, shader-aware material data, and per-actor material overrides (ADR 0018)

Notes / Future Work

• Crouch lowers the camera and movement speed; the collider stays full-height for stability.
• The editor asset browser is filesystem-backed with folder/tree navigation, grid/list views, texture and model thumbnails (glTF albedo fast-path; offscreen render studio for FBX and untextured models), material sphere thumbnails, search/filter/sort controls, expandable model subasset shelves, and a staged details pane. File → Import Assets accepts glTF/GLB and FBX (binary; copies sibling .fbm texture folders when present). Model assets generate normalized static mesh manifests under assets/meshes/generated/; drag/drop uses StaticMeshRenderer by default with imported asset refs and optional separate static mesh collider components. Expanded mesh subassets generate independent thumbnails and can be placed independently. Asset details can switch placement to Scene Instance for ModelRef/SceneRoot playback, shared material assets can be edited from the browser, and delete actions move files to assets/.trash/. Skeletal animation playback is not supported by the static mesh path yet.
• Prefab instances use stable asset IDs (PrefabInstance + registry) with serialized PrefabOverrides (transform, material, per-child visibility by name). Inspector Apply/Revert per field group; Unpack removes the instance link.
• Material assets are RON files under assets/materials/; shader schemas live under assets/shaders/. MaterialDesc stores shader kind, typed parameters, texture bindings, and StandardMaterial fields. The Asset Browser material details editor can apply shader schemas, edit typed parameters/textures, and regenerate sphere thumbnails. Actor inspector edits create per-actor MaterialOverride data for static mesh slots instead of mutating shared material assets.
• Per-field reflect undo for all components remains future work; typed shared inspectors cover the common authoring path.
• The authoring/hydration layer is intentionally small so richer asset workflows (terrain, material graphs, lighting profiles) can be added without changing the scene format foundation.
• The M2 sim split keeps camera pitch as local presentation state; body yaw and movement are fixed-step intent consumers. M3 should map the existing protocol envelopes onto Lightyear and add server-authoritative snapshots/prediction rather than broadening the local input path ad hoc.
• The editor renders egui on a dedicated full-window Camera2d (PrimaryEguiContext, RenderLayers::none(), auto_create_primary_context = false) so the 3D viewport camera can be cropped to the viewport panel without cropping egui itself. Attaching egui to a viewport-cropped 3D camera makes egui_dock lay out into a NaN rect and panics in advance_cursor_after_rect.