Annex E
(informative)

Examples

E.10.3 - Column Straight Rectangle Tessellation

Example overview

The various examples demonstrate the use of tessellated items with vertex list and index, and optionally normal list and index.

The example shows a straight column with a rectangular cross section being tessellated with a mesh. Figure E.A and Figure E.B display the rendering in a target application.

The example shows a tessellation with adding the normals at each vertex to the data set. The list of vertices given by the IfcCartesianPointList3D and the list of normals given by the IfcTriangulatedFaceSet.Normals are corresponding lists, therefore the IfcTriangulatedFaceSet.NormalIndex is not provided and the IfcTriangulatedFaceSet.CoordIndex applies to both lists.

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_DEV_20bdb3d'));
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 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                    */
/* 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;