Specification of a CAD*1 neutral file for CAD geometry : wireframes, surfaces, solids : version 3.3

to the Specification.- 1.1 Purpose.- 1.2 The relation between this proposal and STEP.- 1.3 Stucture of the document.- Approach.- Basic principles.- 3.1 Use of formal languages.- 3.2 Informal description of the CAD data schema.- 3.2.1 Entities and attributes.- 3.2.2 References.- 3.2.3 Properties.- 3.2.4 Scope.- 3.2.5 World.- 3.2.6 Assemblies and components.- 3.2.7 Geometry.- 3.2.7.1 Curves and surfaces.- 3.2.7.2 Solids Models.- 3.2.7.3 Instancing and placement.- 3.2.8 User-defined name.- 3.2.9 Libraries and external references.- 3.2.10 Parametric Models and macros.- 3.2.11 User records.- 3.2.12 Grouping mechanisms.- 3.3 The physical level.- 3.3.1 Strictly sequential,free format,block structure.- 3.3.2 Metafiles,letters and alphabets.- 3.4 Validation of the CAD model transfer.- 3.4.1 Validation of the opertational behaviour of the model.- 3.4.2 Validation of the geometry.- Reference Manual.- The high level data specification language HDSL.- 4.1 Type declaration.- 4.2 Predefined types.- 4.2.1 The type Integer.- 4.2.2 The type Real.- 4.2.3 The type Logical.- 4.2.4 The type String.- 4.2.5 The type User_Defined_Name.- 4.2.6 The NIL.- 4.2.7 The D2,D3.- 4.2.8 The type Arithmetic_Expression.- 4.3 Composite types.- 4.3.1 Enumeration types.- 4.3.2 Fixed structures types.- 4.3.3 Lists.- 4.3.4 Classes.- 4.4 The types Reference,Ref_Only.- 4.5 Generic types.- 4.5.1 Parametric enumeration types.- 4.5.2 Parametric structure.- 4.5.3 Parametric lists.- 4.5.4 Parametric classes.- 4.5.5 Variant structures.- 4.5.6 Variant classes.- 4.5.7 Generic structures.- 4.5.8 Generic enumerations.- 4.5.9 Generic classes.- 4.5.10 Generic lists.- 4.6 The predefined function Dimension.- 4.7 Rules applying to building a schema with HDSL.- 4.8 Semantics of reference models defined with HDSL.- 4.8.1 Entering entities.- 4.8.2 Interrogating the information content of the environment.- 4.8.3 Identifying entities by textual means.- 4.8.4 Identifying entities by interacvite picking.- 4.8.5 Identifying properties.- 4.8.6 Creating a new entity.- 4.8.7 Creating a new property or relation.- 4.8.8 Deleting an existing entity.- 4.8.9 Deleting an existing property or relation.- 4.8.10 Modifying values of attributes.- 4.8.11 Invoking a modeling function.- 4.8.12 Invoking evaluation functions.- 4.8.13 Linear transformations.- The CAD*I reference model specification.- 5.1 Attribute types for general use.- 5.1.1 Any.- 5.1.2 Dim.- 5.1.3 Type_ID.- 5.1.4 Update.- 5.1.5 List of predefined values.- 5.2 General data base structure.- 5.2.1 World.- 5.2.2 Assembly.- 5.2.3 Component.- 5.2.4 Part_Library.- 5.2.5 Routine_Library.- 5.3 Referencing mechanisms.- 5.3.1 Index_Entry.- 5.3.2 Ref_External.- 5.3.3 Ref_Part_Library.- 5.3.4 Ref_Any.- 5.4 Geometric model entities.- 5.4.1 Geometric_Model.- 5.4.2 Wireframe_Model.- 5.4.3 Surface_Model.- 5.4.4 Solid_Model.- 5.5 Points and Curves.- 5.5.1 Attribute types related to curves.- 5.5.1.1 Curve_Transition_Code.- 5.5.2 Direction.- 5.5.3 Point.- 5.5.4 Curves classes.- 5.5.4.1 Curve.- 5.5.4.2 Elementary_Curve.- 5.5.4.3 Bounded_Curve.- 5.5.4.4 Closed_Curve.- 5.5.5 Elementary curves.- 5.5.5.1 Line.- 5.5.5.2 Line_Segment.- 5.5.5.3 Circle.- 5.5.5.4 Ellipse.- 5.5.5.5 Hyperbola.- 5.5.5.6 Parabola.- 5.5.5.7 Polygon.- 5.5.5.8 B_Spline_Curve.- 5.5.6 Derived curve entities.- 5.5.6.1 Trimmed_Curve.- 5.5.6.2 Composite_Curve.- 5.5.7 Curves with functional dependency.- 5.5.7.1 Offset_Curve.- 5.6 Surfaces.- 5.6.1 Surface classes.- 5.6.1.1 Surfaces.- 5.6.1.2 Rectangular_Surface.- 5.6.1.3 Elementary_Surface.- 5.6.2 Planar_Surface.- 5.6.3 Spherical_Surface.- 5.6.4 Conical_Surface.- 5.6.5 Cylindrical_Surface.- 5.6.7 B_Spline_Surface.- 5.6.8 Surface_of_Revolution.- 5.6.9 Surface_of_Translation.- 5.6.10 Rectangular_Trimmed_Surface.- 5.6.11 Rectangular_Composite_Surface.- 5.6.12 Curve_Bounded_Surface.- 5.6.13 Offset_Surface.- 5.7 Geometry on surfaces.- 5.7.1 Surface_Curve.- 5.7.2 Classes of curves on surfaces.- 5.7.2.1 Curves_On_Surface.- 5.7.3 Point_On_Surface.- 5.7.4 Curves on surfaces.- 5.7.5 Elementary curves on surface.- 5.7.5.1 Elementary_Curve_On_Surface.- 5.7.5.2 Line_Segment_On_Surface.- 5.7.5.3 B_Spline_Curve_On_Surface.- 5.7.6 Intersection_Curve.- 5.7.7 Derived curves on surfaces.- 5.7.7.1 Trimmed_Curve_On_Surface.- 5.7.7.2 Composite_Curve_On_Surface.- 5.8 Boundary representations.- 5.8.1 Standard boundary representation.- 5.8.1.1 B_Rep.- 5.8.1.2 Shell.- 5.8.1.3 Face.- 5.8.1.4 Face_Surface.- 5.8.1.5 Loop.- 5.8.1.6 Edge_Loop.- 5.8.1.7 Edge.- 5.8.1.8 Edge_Curve.- 5.8.1.9 Vertex_Loop.- 5.8.1.10 Vertex.- 5.8.2 The Poly_Hedron:a boundary representation with planar faces.- 5.8.2.1 Poly_Hedron.- 5.8.2.2 Poly_Shell.- 5.8.2.3 Poly_Face.- 5.8.2.4 Poly_Loop.- 5.8.3 An experimental compound boundary representation.- 5.8.3.1 Compound_B_Rep.- 5.8.3.2 Region.- 5.9 Constructive solid geometry.- 5.9.1 Construct.- 5.9.2 Boolean.- 5.9.3 Bool_Operand.- 5.9.4 Bool_Operator.- 5.9.5 Primitive.- 5.9.6 Primitives for consturctive solid geometry.- 5.9.6.1 Planar_Halfspace.- 5.9.6.2 Regular_Prism.- 5.9.6.3 Box.- 5.9.6.4 Solid_Cylinder.- 5.9.6.5 Solid_Sphere.- 5.9.6.6 Truncated_Cone.- 5.9.6.7 Truncated_Pyramid.- 5.9.6.9 Solid_Torus.- 5.9.6.10 Contour_Element.- 5.9.6.11 Linear_Sweep.- 5.9.6.12 Rotational_Sweep.- 5.10 Hybrid_Solid.- 5.11 General grouping mechanism.- 5.11.1 Aspect.- 5.11.2 Geometry_Association.- 5.12 Placement and instancing.- 5.12.1 Geometric.- 5.12.2 Instance.- 5.12.3 Rotation.- 5.12.4 Rot_Axis.- 5.12.5 Rot_Global.- 5.12.6 Rot_Matrix.- 5.12.7 Placement.- 5.13 Test data elements.- 5.13.1 Test_Relation_For_D2_Wireframe.- 5.13.2 Test_Relation_For_D3_Wireframe.- 5.13.3 Test_Relation_For_Surface_Model.- 5.13.4 Test_Relation_For_Solid_Model.- 5.14 Miscellaneous.- 5.14.1 Material.- 5.14.2 Private record structures attached to CAD data.- 5.14.2.1 Record.- 5.14.2.2 Record_Type.- 5.14.3 interfacing with other data bases (not CAD data bases).- 5.14.3.1 Data_Base_Brigde.- 5.14.3.2 Data_Base_Link.- 5.15 Parametric modeling.- 5.15.1 Predefined.- 5.15.2 Integer.- 5.15.3 Integer_Expression.- 5.15.4 Real.- 5.15.5 Real_Expression.- 5.15.6 Macro.- 5.15.7 Routine.- 5.15.8 Formal_Parameter.- 5.16 Extensions of the reference mocel under consideration.- 5.16.1 Poly_Curve.- 5.16.2 Poly_Surface.- 5.16.3 Presentation of line geometry.- Levels of schema implementations.- 6.1 The geometric modeling levels.- 6.1.1 Two-dimensional wireframes.- 6.1.2 Three-dimensional wireframes.- 6.1.3 Surfaces models.- 6.1.4 Single modeling type solids.- 6.1.4.1 Pure CSG models.- 6.1.4.2 Pure Poly_Hedron models.- 6.1.4.3 Pure boundary representation models.- 6.1.5 Hybrid models.- 6.1.6 Full geometric capabilities.- 6.2 The assembly structure.- 6.2.1 No assembly structure with three levels.- 6.2.2 Full assembly structure.- 6.3 Parametric models and macros.- 6.3.1 No parametric models,no macros.- 6.3.2 Only one parametric capability.- 6.3.2.1 Parametric models only.- 6.3.2.2 Macro parametric only.- 6.3.3 Full parametric models capabilities.- 6.4 References.- 6.4.1 No external references,no library references.- 6.4.2 No external references.- 6.4.3 No library references.- 6.4.4 Full referencing capabilities.- The physical layer.- 7.1 The physical level.- 7.1.1 Tape characteristics.- 7.1.2 File transfer via computer networks.- 7.2 The metafile level.- 7.3 The alphabet level.- 7.4 Tokens of the neutral file language.- 7.4.1 Arithmetic expressions.- 7.5 The statement level.- 7.5.1 Basic statement productions.- 7.6 Rules for translating from the HDSL into BNF.- 7.7 Structure of the neutral file language.- Implementation Guidelines.- Definition of the state machine post-processor.- 8.1 The finite state approach.- 8.2 Interpreter.- 8.2.1 Begin interpretation of the neutral file.- 8.3 World.- 8.4 Entity with scope (expect World).- 8.5 Begin scope definition.- 8.6 End scope definition.- 8.7 Close entity.- 8.7.1 Close world.- 8.7.2 Close entity (expect World).- 8.8 Entity world.- 8.9 Property definition.- 8.10 Interpertation of argument lists (expect references).- 8.11 References.- 8.12 Examples of error messages.- State lists.- Relationships between operating systems and CAD.- 10.2 Data bases and libraries.- Programming rules for CAD*I processors.- 11.1 Programming language.- 11.1.1 Determination of the programming language.- 11.1.2 Requirements of the structured programming.- 11.2 Software design.- 11.2.1 Organisation of the program.- 11.2.2 Software commenting.- Programming interface.- 12.1 Mapping of HDSL data types onto Fortran.- 12.2 Application program interface routines.- Comments on pre-processors.- 13.1.1 Implementation of level 1 and level 2 per-processor routines.- 13.1.1.1 Level 1 routines.- 13.1.1.2 Level 2 routines.- 13.1.1.3 An example level 3 routine.- Comments on post-processors.- The interface of the CAD*I parser.- 15.1 Parse tree.- 15.2 Example.- Appendix A. The graphical alphabet.- Appendix B. The escape sequences.- B.1 The Latin alphabet (ISO6937).- B.2 The Greek alphabet.- B.3 The Kanji alphabet.- Appendix C. Alphabet translation into a private alphabet.- Appendix D. A neutral file for fixed format letters.- Appendix E. Examples of a CAD*I neutral files.