Module creo 

PTC Creo parts (.prt.N): a preview mesh tessellated from the exact B-rep the file stores – Creo keeps no display tessellation of the body. See docs/src/research/creo-brep-preview.md. Assemblies (.asm.N) are put together from their parts (asm, services::assemblies).

• asm: the components of an assembly and their placements;
• container: the text table of contents and the LZW-compressed sections;
• tagged: the self-describing binary format of a section and its compact numbers;
• brep: faces (plane, cylinder, cone, torus) with their contours and the edges sampled in both faces’ parameter spaces; the per-face parametrisation is resolved across shared edges;
• tess: regions per face, ear clipping in the parameter plane, welding, PN refinement along the analytic normals.

Modules

asm

Creo assemblies (.asm.N): the components and their placements, read from section NeuAsmSld (docs/src/research/creo-assembly-preview.md).

brep

The B-rep of a Creo part as the VisibGeom section stores it: analytic surfaces with their contours, and edges sampled as point lists in the parameter spaces of both neighbouring faces.

container

The container of PTC Creo part files (.prt.N): a text header, a table of contents in fixed-width text records and named sections, some of them compressed with Unix compress (LZW).

freeform

The freeform surfaces of the Creo B-rep: interpolating bicubic splines (splsrf), rolling-ball fillets (fillet_srf) and ruled surfaces (ruled_srf). All three carry absolute 3D data, so they need no convention and even seed the resolution of the analytic faces.

tagged

The tagged binary format of Creo sections (docs/src/research/creo-brep-preview.md).

tess

Tessellation of the Creo B-rep: contours → regions → ear clipping in the parameter plane → 3D, with every edge evaluated once on its most exact face so that neighbouring faces share identical vertices, then refined with PN triangles along the analytic normals.

Constants

UNIT_SYSTEM

The section with the unit system (parts and assemblies).

VISIBLE_GEOMETRY

The section with the visible B-rep.

Functions

unit_mm

Millimetres per length unit of the file (1 when the file names none or one not known): the unit’s name follows Offset in the names (string_xar) of the UnitSystemDef section – mm, in, …; other systems give the metres per unit in double_xar[0].