Scene3d Authoring

Scene3D Authoring

Compose the Scene3D brick: assets in, objects/lights/camera/effects declared, verified in the simulator. The exact property shapes live in references/scene3d-properties.md.

Announce at start: "I'm using the scene3d-authoring skill to build the 3D scene."

Step 1: Get assets into the project

• Model files (.glb preferred; .gltf/.usd/.usdz also load): upload with media_upload_files (if the media tools are unavailable, ask the user to upload via the Controller UI). Keep the returned url and md5.
• Environment backgrounds: equirectangular .hdr/.exr (or LDR image), uploaded the same way.
• md5 is not optional. Every objects[] entry with a url needs its md5 — it keys the asset cache and lets Preload rewrite remote URLs to local files so scenes work offline. A missing md5 = a scene that breaks on disconnected devices.
• Primitives (box, sphere, plane, cylinder, cone, torus, text) need no asset at all — reach for them before Blender when a simple shape does the job.

Step 2: Declare the scene

Edit the brick's properties via the project editing tools (edit_entry / edit_canvas_items). Give every object a stable, meaningful id — ids are how scripts, actions, and events refer to objects later.

Composition order that works:

1. Objects — { id, type, url, md5, position, rotation, scale }. One hero object at the origin for viewers; use nodes[] overrides to retint or hide named parts inside a loaded model (names come from blender-pipeline's inspect output).
2. Lighting — start from a look preset (reference doc): viewer = hemisphere ambient + one directional key with shadows; ambient scene = HDR environment doing the lighting (backgroundImage + env intensity) with lights minimal.
3. Camera + controls — perspective, default position (3,3,5) target origin frames a ~1–2-unit model. Product viewer: controls: 'orbit', damping on, min/max distance clamped, autoRotate for attract. Non-interactive signage: controls: 'none'.
4. Renderer + post-FX — defaults (toneMapping: 'aces', exposure 1) are good. Add bloom only with emissive content (keep bloomThreshold ≥ 1 so only highlights glow); ssao and shadows are the expensive toggles — budget them per device class.
5. Animations — glTF clips play by clip name (from the inspect output): set an object's animation property for autoplay, or trigger the play/stop animation actions at runtime (loop, speed).

Step 3: Verify

1. Compile the project (compile), fix schema errors.
2. Simulator: check load events fire (wire BRICK_SCENE_3D_ON_LOAD_ERROR to a visible fallback during development — a missing asset otherwise renders as nothing), framing at the app's real aspect ratio, and materials under your lighting (metals go black without an environment or enough light — add backgroundImage or a hemisphere light).
3. Watch performance while previewing: if it stutters, disable SSAO/shadows first, then reduce texture/poly budgets (blender-pipeline optimize).

Step 4: Deploy

Deploy through the normal project flow (the built-in bricks-cli skill covers deploy and on-device inspection). Assets preload for offline use via their md5s — first boot after deploy needs network to fill the cache. tvOS is experimental for Scene3D: verify on the actual device before promising it.

When Not To Use

• Creating/converting/optimizing the 3D asset files — blender-pipeline.
• Runtime behavior: input, per-frame motion, picking, game logic — scene3d-interactions.
• Flat 2D content that doesn't need a 3D renderer — regular bricks are cheaper on every device.