附录 E
（资料性）

示例

E.10.3 - 直线矩形柱细分面（Column Straight Rectangle Tessellation）

示例概述（Example overview）

这些示例演示了使用带有顶点列表和索引（以及可选的法线列表和索引）的细分面项。

本示例展示了一根矩形截面直柱被网格细分面化的结果。图E.A和图E.B展示了在目标应用程序中的渲染效果。

The example shows a tessellation with adding the normals at each vertex to the data set. The list of vertices given by the IfcCartesianPointList3D（笛卡尔点列表3D） and the list of normals given by the IfcTriangulatedFaceSet（三角化面集）.Normals are corresponding lists, therefore the IfcTriangulatedFaceSet（三角化面集）.NormalIndex is not provided and the IfcTriangulatedFaceSet（三角化面集）.CoordIndex applies to both lists.

IFC-SPF 源代码（IFC-SPF source）

ISO-10303-21;
HEADER;

FILE_DESCRIPTION(('ViewDefinition [ReferenceView_V1.0]'),'2;1');
FILE_NAME('column-straight-rectangle-tessellation.ifc','2014-07-08T19:20:14',('redacted'),(''),'redacted','redacted','');
FILE_SCHEMA(('IFC4X3_ADD2'));
ENDSEC;

DATA;

/* set the default units - and the units used for geometric representations                       */
/* here imperial units (inch) are used                                                            */
/* ---------------------------------------------------------------------------------------------- */
#12= IFCSIUNIT(*,.LENGTHUNIT.,$,.METRE.);
#13= IFCMEASUREWITHUNIT(IFCLENGTHMEASURE(0.0254),#12);
#14= IFCDIMENSIONALEXPONENTS(1,0,0,0,0,0,0);
#15= IFCCONVERSIONBASEDUNIT(#14,.LENGTHUNIT.,'inch',#13);
#36= IFCUNITASSIGNMENT((#15));

/* set the context of the IFC4 exchange file                                                      */
/* name, units and geometric representation context                                               */
/* note: IfcOwnerHistory（所有者历史） is not in scope of the IFC4 reference view                               */
/* ---------------------------------------------------------------------------------------------- */
#37= IFCPROJECT('0CxDbxzA1B4eLeOw9eIjQx',$,'Project',$,$,$,$,(#40),#36);

/* set the representation context for 3D body, and 2D axis representation                         */
/* no north direction and no geo-spatial coordinates are provided                                 */
/* ---------------------------------------------------------------------------------------------- */
#38= IFCCARTESIANPOINT((0.,0.,0.));
#39= IFCAXIS2PLACEMENT3D(#38,$,$);
#40= IFCGEOMETRICREPRESENTATIONCONTEXT('3D','Model',3,1.0E-05,#39,$);
#41= IFCGEOMETRICREPRESENTATIONSUBCONTEXT('Body','Model',*,*,*,*,#40,$,.MODEL_VIEW.,$);

/* defines the default site (as required as the minimum spatial element)                          */
/* ---------------------------------------------------------------------------------------------- */
#44= IFCSITE('0M0akNk9f3hOH9u2awmtre',$,'Site #1',$,$,#67,$,$,.ELEMENT.,$,$,$,$,$);
#45= IFCRELAGGREGATES('2y_abP04108BvIhy2WfsHm',$,$,$,#37,(#44));
#67= IFCLOCALPLACEMENT($,#69);
#68= IFCCARTESIANPOINT((0.,0.,0.));
#69= IFCAXIS2PLACEMENT3D(#68,$,$);

/* defines the column with rectangular cross section as a model element                           */
/* using tessellated geometry                                                                     */
/* ---------------------------------------------------------------------------------------------- */
#71= IFCCOLUMN('2WUGYBphrFv8aLIFJCmiIk',$,'Column #1',$,$,#121,#111,$,.COLUMN.);
#111= IFCPRODUCTDEFINITIONSHAPE($,$,(#154));
#116= IFCRELCONTAINEDINSPATIALSTRUCTURE('0F1oUoJsr5ZwxKAxiD1Vep',$,$,$,(#71),#44);
#119= IFCDIRECTION((0.,0.,1.));
#120= IFCDIRECTION((1.,0.,0.));
#121= IFCLOCALPLACEMENT(#67,#126);
#125= IFCCARTESIANPOINT((432.,288.,48.));
#126= IFCAXIS2PLACEMENT3D(#125,#119,#120);
#154= IFCSHAPEREPRESENTATION(#41,'Body','Tessellation',(#288));

/* the triangulated tessellation also includes the normals per face and vertex                    */
/* in this case, the vertex list and the normal list are corresponding lists,                     */
/* hence no separate normal index has to be provided at IfcTriangulatedFaceSet（三角化面集）                    */
/* it generated longer lists, but is in line with many graphic APIs using a single buffer list    */
/* ---------------------------------------------------------------------------------------------- */
#287= IFCCARTESIANPOINTLIST3D(((-4.,4.,0.),(-4.,-4.,0.),(4.,-4.,0.),(4.,4.,0.),(-4.,4.,120.),(-4.,-4.,120.),(4.,-4.,120.),(4.,4.,120.),(-4.,4.,0.),(-4.,-4.,0.),(-4.,-4.,120.),(-4.,4.,120.),(-4.,-4.,0.),(4.,-4.,0.),(4.,-4.,120.),(-4.,-4.,120.),(4.,-4.,0.),(4.,4.,0.),(4.,4.,120.),(4.,-4.,120.),(4.,4.,0.),(-4.,4.,0.),(-4.,4.,120.),(4.,4.,120.)),$);
#288= IFCTRIANGULATEDFACESET(#287,((0.,0.,-1.),(0.,0.,-1.),(0.,0.,-1.),(0.,0.,-1.),(0.,0.,1.),(0.,0.,1.),(0.,0.,1.),(0.,0.,1.),(-1.,0.,0.),(-1.,0.,0.),(-1.,0.,0.),(-1.,0.,0.),(0.,-1.,0.),(0.,-1.,0.),(0.,-1.,0.),(0.,-1.,0.),(1.,0.,0.),(1.,0.,0.),(1.,0.,0.),(1.,0.,0.),(0.,1.,0.),(0.,1.,0.),(0.,1.,0.),(0.,1.,0.)),.T.,((1,3,2),(1,4,3),(5,6,7),(5,7,8),(9,10,11),(9,11,12),(13,14,15),(13,15,16),(17,18,19),(17,19,20),(21,22,23),(21,23,24)),$);
ENDSEC;

END-ISO-10303-21;