Blender void

[TheTechromancer]

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Blender void

Adds a new Blender void layer that shows a live view of a Blender session — with a transparent background, so you can paint behind and around the 3D scene and treat Blender as just another layer. It pairs with a companion Blender extension (darkly-art/blender-extension) that captures the 3D viewport (or a camera POV), encodes alpha-carrying PNG frames, and serves them over a localhost HTTP server as a single chunked response of length-prefixed frames ([4-byte big-endian length][image bytes]).

Rust core

• gpu/voids/blender.rs — the new void, registered through the standard modular register() mechanism. It is a thin config over the shared video_stream_void machinery (the same base as the camera and screenshare voids), declaring freeze, frame_divisor, and a new url string param. url is document-persisted state the frontend reads to know where to connect (default http://localhost:8765/stream); the Rust void never interprets it.
• CaptureKind::Stream — a third capture kind alongside Camera / Display, serialized to the frontend as "stream" so the app knows to source frames via HTTP fetch rather than a MediaDevices API.
• Passthrough params in video_stream_void — the shared machinery now keeps a param_snapshot of every param in schema order, so params it doesn't model (like url) round-trip through from_params → param_values (save/load) and update_params (the properties panel) instead of being silently regenerated from their defaults. Covered by a regression test (passthrough_param_round_trips) plus unit tests on the void's registration, params, and default transform.

Frontend

• lib/frameSource.ts — new abstract FrameSource base extracted from MediaStreamSource, owning the per-tick lifecycle every external-frame void shares: the visible / frozen / frame-divisor / has-new-frame gate, off-thread createImageBitmap decode (with the document-resolution downscale cap), and the uploadVoidExternalImage GPU upload. Subclasses only supply where the frame comes from.
• lib/httpStreamSource.ts — the Blender-side subclass. It fetches the stream URL, pumps the response body in the background, and reassembles complete length-prefixed frames independent of HTTP chunk boundaries. Frames decode with premultiplyAlpha: 'none' to preserve the straight alpha the add-on emits, and the blob carries no MIME type — createImageBitmap content-sniffs, so the add-on can switch codecs without a frontend change. A change-driven hasFrameReady gate means a static Blender scene drives zero decode and zero GPU work. Reconnect-on-url-change, supersede-in-flight-connection, and clean disconnect handling (with human-readable errors like "Is the add-on running?") are all covered by unit tests (httpStreamSource.test.ts).
• lib/mediaStreamSource.ts — refactored down to a FrameSource subclass that only supplies the live <video> frame and the MediaStream lifecycle; all duplicated tick/decode/upload logic moved into the base.
• state/app.svelte.ts — the media-stream registry generalized to a FrameSource registry (streamSources, startStreamSource, stopStreamSource, …). stream voids connect immediately on creation — no gesture or permission gate is needed for a localhost HTTP stream — while camera/screenshare keep their in-gesture acquisition path. The layer-tree reconciler additionally pushes url changes to a live source, and the existing reap/freeze/visibility/divisor plumbing applies unchanged.
• UI — the void picker skips MediaStream acquisition for stream voids; VoidProperties gains a string-param text input (used for url) and a per-kind connect verb ("Connect to Blender" alongside "Resume camera" / "Resume screen share"), with disconnect errors surfaced in the same notice camera/screenshare use.

Misc

• README "Features & Roadmap": added `[x] Blender stream void.

The companion Blender extension itself lives in its own repository and is not part of this diff.

[codecov]

Codecov Report

❌ Patch coverage is 97.75281% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/darkly/src/gpu/video_stream_void.rs	96.77%	2 Missing ⚠️

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