OneCAD-Simulation/tools/demo-video/README.md

Demo video

make.py regenerates the README's demo, docs/media/ibeam-analysis.mp4 and docs/media/ibeam-analysis.gif: an agent analyses an I-beam cantilever over MCP while the FieldCraft desktop app shows each step.

python3 tools/demo-video/make.py                  # build, run, encode into docs/media
python3 tools/demo-video/make.py --no-build       # with the release binaries already built
python3 tools/demo-video/make.py --frames /tmp/f  # also keep the captured pictures
cd tools/demo-video && python3 -m unittest        # test the caption drawing

Needs Python 3 (standard library only), a display for the FieldCraft window (the pictures are drawn offscreen, so a locked screen is fine) and ffmpeg with libx264 on the PATH (or FFMPEG). It honours CARGO_TARGET_DIR.

What it does:

1. Builds fieldcraft, fieldcraft-cli and the testkit's corpus tool (release).
2. Writes the corpus cantilever I-beam (tests/corpus/cantilever-i-beam: 40 x 40 mm, 3 mm flanges, a 2 mm web upright, 200 mm long along x) as a .solidcraft design to a temporary folder with corpus --part cantilever-i-beam --design.
3. Starts FieldCraft (fieldcraft) with --control PORT and fieldcraft-cli mcp --connect 127.0.0.1:PORT, and speaks MCP (JSON-RPC over stdio) to it. Every step is an MCP tool call: open the design, mesh (hex_sweep, 4 mm), batch (steel, a solid section, the root clamp, a kinematic coupling of the free end at x = 200 mm to a reference point loaded with 1000 N down, −z), check_model, solve (static), and show_results for the von Mises contours on the undeformed shape (scale: 0) and then the deformed shape, its scale swung (eased) from 0 to 150, back to 0 and out to 150 again. Every picture is the MCP screenshot tool with source: window (the whole window drawn offscreen, ui.capture): the setup in the iso view, the results through its camera argument (the iso orientation drawn back to 420 mm so the contour legend leaves the beam clear), and to close, a slow orbit of 60 pictures, one camera angle each, from the iso view half way round the beam. Each stage holds for 2 to 3 seconds.
4. Captions each stage with the MCP tool it calls and what it does (open · tests/corpus/…, mesh · hex sweep 4 mm, solve · static, …) in a band under the window. caption.py draws the bars in the standard library: a minimal TrueType reader (cmap format 4, loca, simple and composite glyf outlines, hmtx advances), a scanline rasteriser (non-zero winding, anti-aliased) and a PNG writer, with the interface's own font (crates/ui-egui/fonts/Inter-SemiBold.ttf, SIL OFL 1.1). ffmpeg pads each window picture with the band and lays the bar over it with its overlay filter.
5. Encodes the pictures at 10 frames per second, each held for its stage, into the MP4 (H.264, 1280 x 848) and the GIF (960 px, its own palette), and prints the tip deflection and the peak von Mises stress.

The theme is FieldCraft's default (dark).

The script checks the solution against beam theory and stops when it is off. Tip deflection: P L³ / 3 E I = 0.1429 mm in bending plus P L / G A_web = 0.0335 mm in shear, 0.1763 mm; the solution gives 0.1764 mm (within 3 %). Root bending stress: P L c / I = 45.0 MPa (I = 88 871 mm⁴); the solution's stress_xx on the top flange, fitted along the beam between one depth from either end and extrapolated to the root, gives 44.8 MPa (within 2 %). At the root itself the clamp, which stops the section's Poisson contraction, adds a local peak (62 MPa stress_xx, 56 MPa von Mises) that beam theory does not have.