IFC 4.3.1.0 (IFC4X3_ADD1)

8.12.3.21 IfcIndexedTriangleTextureMap

8.12.3.21.1 Semantic definition

The IfcIndexedTriangleTextureMap provides the mapping of the 2-dimensional texture coordinates to the surface onto which it is mapped. It is used for mapping the texture to triangles of the IfcTriangulatedFaceSet.

The IfcIndexedTriangleTextureMap defines an index into an indexed list of texture coordinates. The TexCoordIndex is a two-dimensional list, where

  • first dimension is the unbounded list of faces corresponding to the list of triangles defined by CoordIndex at IfcTriangulatedFaceSet;
  • second dimension is the fixed list of three indices to texture vertices corresponding to the fixed list of indices to vertices at IfcTriangulatedFaceSet

The TexCoords defined at supertype IfcIndexedTextureMap are a two-dimensional list of texture coordinates provided by two parameter values. Each index of the second dimension list of TexCoordIndex points to a texture vertex in TexCoords.

Figure 1 shows the use of IfcTriangulatedFaceSet with textures.

IfcIndexedTriangleTextureMap_01
Figure 8.12.3.21.B illustrates an IfcTriangulatedFaceSet represented by :
IfcTriangulatedFaceSet.CoordIndex:
((1,6,5), (1,2,6), (6,2,7), (7,2,3), (7,8,6), (6,8,5), (5,8,1), (1,8,4), (4,2,1), (2,4,3), (4,8,7), (7,3,4))

IfcCartesianPointList.CoordList:
((0.,0.,0.), (1.,0.,0.), (1.,1.,0.), (0.,1.,0.), (0.,0.,2.), (1.,0.,2.), (1.,1.,2.), (0.,1.,2.))

IfcIndexedTriangleTextureMap.TexCoordsIndex:
((1 4 3), (1 2 4), (3 1 4), (4 1 2), (8 7 6), (6 7 5), (4 3 2), (2 3 1), (5 8 7), (8 5 6), (2 4 3), (3 1 2))

IfcTextureVertexList.TexCoordsList:
((0. -0.5), (1. -0.5), (0. 1.5), (1. 1.5), (0. 0.), (0. 1.), (1. 0.), (1. 1.))
IfcIndexedTriangleTextureMap_example-01
Figure 8.12.3.21.B — Indexed triangle texture map geometry

8.12.3.21.2 Entity inheritance

8.12.3.21.3 Attributes

# Attribute Type Description
IfcTextureCoordinate (1)
1 Maps LIST [1:?] OF IfcSurfaceTexture

Reference to the one (or many in case of multi textures with identity transformation to geometric surfaces) subtype(s) of IfcSurfaceTexture that are mapped to a geometric surface by the texture coordinate transformation.

IfcIndexedTextureMap (2)
2 MappedTo IfcTessellatedFaceSet

Reference to the IfcTessellatedFaceSet to which it applies the texture map.

3 TexCoords IfcTextureVertexList

Indexable list of texture vertices.

Click to show 3 hidden inherited attributes Click to hide 3 inherited attributes
IfcIndexedTriangleTextureMap (1)
4 TexCoordIndex OPTIONAL LIST [1:?] OF LIST [3:3] OF IfcPositiveInteger

Index into the IfcTextureVertexList for each vertex of the triangles representing the IfcTriangulatedFaceSet.

Table 8.12.3.21.A

8.12.3.21.4 Formal representation

ENTITY IfcIndexedTriangleTextureMap
 SUBTYPE OF (IfcIndexedTextureMap);
	TexCoordIndex : OPTIONAL LIST [1:?] OF LIST [3:3] OF IfcPositiveInteger;
END_ENTITY;

8.12.3.21.5 References

8.12.3.21.6 Changelog

8.12.3.21.6.1 IFC4

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