yhz5613813/cadflow/cadflow-flexible-model

CadFlow Static Flexible Modeling

Model the shape that a flexible product is intended to have at one fixed configuration. This skill is for geometry generation, not physical simulation. Use import cadflow as cad for the package and import the flexible domain from cadflow.flexible.

Choose the representation

• Use FlexiblePanel for an arbitrary rectangular control-point surface.
• Use RingSection plus sectioned_panel for sleeves, trouser legs, tubes,

torsos, rolled sheets, or other section-driven garment parts.

• Use FlexibleModel to concatenate independent panels while preserving panel

names and index ranges.

• Use positive FlexibleMaterial.thickness for a closed thin shell; use zero

thickness only for an intentionally open surface.

• Use a CadFlow Model/Solid only when the request is a rigid BREP part.

Do not force a cloth panel into a rigid-solid workflow.

Required workflow

1. Extract the design intent: panel boundaries, section centers and axes,

dimensions, material thickness, wrinkle/fold locations, sampling density, output formats, and the fixed pose to model.

1. State units and coordinate assumptions. Normalize section axes and keep the

same unit across all panels.

1. Build one panel at a time. Name panels by semantic role (torso, left_leg,

right_sleeve) rather than by numeric order.

1. Use static wrinkle parameters (wrinkle_amplitude, wrinkle_count, and

wrinkle_phase) as geometry inputs. Never introduce a time loop or solver.

1. Choose sampling density from curvature and inspection needs. Increase

sample_rows/sample_columns where folds are tight; do not hide self- intersections or bad parameterization by oversampling.

1. Build the combined FlexibleMesh, then validate vertex/triangle indices,

finite coordinates, unit normals, non-degenerate triangles, panel ranges, deterministic output, and watertightness when thickness is positive.

1. Export OBJ, binary STL, and metadata JSON. Render orthographic front/side/top

plus a perspective geometry view when the user asks to see the result.

1. Report the exact mesh counts, bounds, area, panel names, thickness, output

paths, and all assumptions.

C++/Python boundary

Keep the boundary stateless and narrow:

• C++ (native/src/flexible/shell_mesh.*) performs dense grid sampling,

periodic seams, smooth normals, thickness offsets, boundary walls, and triangle indexing.

• Python (python/cadflow/flexible.py) owns material/design semantics,

section construction, panel composition, validation, measurement, and file export.

• Do not add C++ callbacks into Python, time state, scene state, collision

state, gravity, velocity, or an XPBD/deformable simulation API.

Minimal section-driven pattern

from cadflow.flexible import (
    FlexibleMaterial, FlexibleModel, RingSection, sectioned_panel,
)
fabric = FlexibleMaterial(name="cotton", thickness=1.2)
torso = sectioned_panel(
    "torso",
    [
        RingSection((0, 0, 0), (1, 0, 0), (0, 1, 0), 220, 130),
        RingSection((0, 0, 500), (1, 0, 0), (0, 1, 0), 250, 145,
                    wrinkle_amplitude=0.02, wrinkle_count=7),
    ],
    control_columns=24,
    sample_rows=48,
    sample_columns=72,
    material=fabric,
)
model = FlexibleModel("static-garment")
model.add_panel(torso)
mesh = model.build()
assert mesh.is_watertight
mesh.write_obj("out/garment.obj")
mesh.write_stl("out/garment.stl")
mesh.write_json("out/garment.json")

For a complete four-view renderer, use examples/cadflow_static_flexible_garment.py as the project-local template.

Failure handling

• Reject non-finite or negative material thickness and invalid control grids.
• Reject non-orthogonal or zero section axes before building a panel.
• Treat non-watertight positive-thickness output as a modeling failure, not as a

cosmetic warning.

• If folds self-intersect, adjust section geometry or wrinkle amplitude; do not

claim physical cloth behavior from a static procedural perturbation.

• If a requested feature requires motion, hand the request back as outside

this skill's scope rather than adding a simulator.