shadecore
Native GLSL shader engine in Rust — Syphon/Spout/FFmpeg/NDI routing.

Output Routing

shadecore always renders into an offscreen framebuffer (FBO). That framebuffer texture is:

  • drawn to the local preview window (always on)
  • optionally published or streamed via the selected output mode

The active output mode is controlled by assets/output.json (or an alternate output configuration file).

Runtime Hotkeys (Default)

1 — Texture Only (Preview)

What it does

  • Disables all external routing.
  • Only the local preview window is active.

When to use it

  • Debugging shaders and uniforms
  • Verifying render correctness
  • Performance testing
  • Running without Syphon / Spout / FFmpeg / NDI dependencies

Expected behavior

  • Lowest overhead
  • Most deterministic execution
  • No external consumers receive frames

2 — Syphon (macOS)

What it does

  • Publishes the rendered OpenGL texture to a Syphon server.

When to use it

  • Routing video into OBS (Syphon input)
  • macOS-based visual tools such as Resolume, MadMapper, TouchDesigner, or VDMX
  • Local, zero-copy GPU workflows

Expected behavior

  • Very low latency
  • GPU texture sharing (no encode, no network)
  • macOS only

Notes

  • Syphon server name is configurable in the output config.
  • Local preview remains active.

3 — Spout2 (Windows)

What it does

  • Publishes the rendered texture as a Spout2 sender.

When to use it

  • OBS on Windows (Spout2 plugin)
  • TouchDesigner, Resolume, or other Windows-based visual tools
  • Local low-latency routing without encoding

Expected behavior

  • Very low latency
  • GPU texture sharing
  • Windows only

Notes

  • Sender name is configurable.
  • Preview remains active.

4 — Stream (FFmpeg RTSP / RTMP)

What it does

  • Spawns an FFmpeg process.
  • Frames are encoded and streamed to a network endpoint.

When to use it

  • Sending video to another machine
  • Feeding RTSP/RTMP servers (e.g., mediamtx)
  • Remote or headless workflows
  • Software that expects a network stream

Expected behavior

  • Higher CPU/GPU load due to encoding
  • Higher latency than texture-sharing outputs
  • Network-visible stream

Common configuration fields

  • stream.ffmpeg_path
  • stream.url
  • codec, bitrate, preset, framerate, resolution

Notes

  • Many encoders (e.g. H.264) require even-numbered frame dimensions.
  • Preview remains active.

6 — NDI (Dedicated Mode)

What it does

  • Sends frames to an NDI sender discoverable on the local network.

Why NDI is separate

  • Requires a different runtime lifecycle
  • Different threading and timing constraints
  • Kept out of the core render loop intentionally

When to use it

  • OBS NDI input workflows
  • LAN-based video routing with automatic discovery
  • Multi-machine studio setups

Expected behavior

  • Network-based video transport
  • Higher overhead than Syphon/Spout
  • Easier discovery than RTSP in many setups

Notes

  • Typically run via a dedicated feature or binary.
  • Uses its own output configuration (e.g. output_ndi.json).
  • Preview behavior depends on NDI mode configuration.

Hotkey Configuration

Hotkeys are defined in the output configuration JSON. This allows:

  • Rebinding keys without recompiling
  • Platform-specific key maps
  • Separate configs per output mode

This design keeps routing logic declarative and reproducible.