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STEP

Table of Contents

Overview

ModelData_ModelReader can read STEP AP203, AP214 or AP242 files. ModelData_ModelWriter can write STEP AP242 files.

Scope

Import Export
  • B-Rep representations
  • assembly structure
  • graphical and semantic PMI
  • B-Rep representations
  • assembly structure
  • graphical and semantic PMI

Mapping

Import Mapping

Below tables show how STEP entities are mapped into MTK entities after import.

Product Structure

STEP Entity MTK Entity
product_definition One of:
next_assembly_usage_occurrence ModelData_Instance
item_defined_transformation Geom_Transformation

Topology

STEP Entity MTK Entity
manifold_solid_brep ModelData_SolidBody
brep_with_voids
shell_based_surface_model ModelData_SheetBody
face_based_surface_model
edge_based_wireframe_model ModelData_WireframeBody
geometric_curve_set
closed_shell ModelData_Shell
oriented_closed_shell
open_shell
advanced_face ModelData_Face
face_surface
curve_bounded_surface
face_bound ModelData_Wire
face_outer_bound
edge_loop
connected_edge_set
composite_curve
boundary_curve
outer_boundary_curve
edge_curve ModelData_Edge
oriented_edge
vertex_point ModelData_Vertex

Geometry

STEP Entity MTK Entity
Surfaces
b_spline_surface_with_knots Geom_BSplineSurface
rational_b_spline_surface
uniform_curve
quasi_uniform_curve
conical_surface Geom_ConicalSurface
cylindrical_surface Geom_CylindricalSurface
offset_surface Geom_OffsetSurface
plane Geom_Plane
rectangular_trimmed_surface Geom_Surface
spherical_surface Geom_SphericalSurface
surface_of_linear_extrusion Geom_SurfaceOfLinearExtrusion
surface_of_revolution Geom_SurfaceOfRevolution
toroidal_surface Geom_ToroidalSurface
Curves
b_spline_curve_with_knots Geom_BSplineCurve
Geom_BSplineCurve2d
rational_b_spline_curve
uniform_curve
quasi_uniform_curve
circle Geom_Circle
Geom_Circle2d
ellipse Geom_Ellipse
Geom_Ellipse2d
hyperbola Geom_Hyperbola
Geom_Hyperbola2d
line Geom_Line
Geom_Line2d
offset_curve Geom_OffsetCurve
Geom_OffsetCurve2d
parabola Geom_Parabola
Geom_Parabola2d
trimmed_curve Geom_Curve

Export Parameters

Export parameters are controlled by ModelData_ModelWriterParameters and applied using ModelData_ModelWriter.SetParameters() . STEP export uses the following parameters:

Parameter Default value Description
ModelData_ModelWriterParameters.WritePCurves false Writes parametric representations of edges on surfaces. Enabling this option provides additional data useful to some computer-aided design (CAD) systems, but may increase the output file size.
ModelData_ModelWriterParameters.WritePMI false Exports graphical and semantic PMI, subject to the limitations below.

Known Limitations

The following limitations apply to STEP export:

  • PMI_SavedView is ignored. PMI elements are exported without their saved view organization.
  • PMI_TextComponent is ignored. Text stored in this graphical component is not exported.
  • PMI_CurveOutline and PMI_CurveOutline2d are discretized and exported as polylines.
  • PMI_SurfaceFinishComponent is ignored.
  • Only the semantic attributes listed below are exported. Other semantic attributes are ignored.

Supported semantic attributes: