IFC 4.3.x development

8.12.3.1 IfcBlobTexture

Change log

IFC4

additions where_rules RasterCodeByteStream
additions where_rules SupportedRasterFormat
deletions where_rules WR11
modificationsattributes RasterCode definitionChanged from boolean to IfcBinary

8.12.3.1.1 Semantic definitions at the entity

An IfcBlobTexture provides a 2-dimensional distribution of the lighting parameters of a surface onto which it is mapped. The texture itself is given as a single binary blob, representing the content of a pixel format file. The file format of the pixel file is given by the RasterFormat attribute and allowable formats are guided by where rule SupportedRasterFormat.

NOTE  Toolbox specific implementations of the binary datatype may restrict the maximum length of the binary blob to capture the raster file content.

For interpretation of the texture nodes see IfcImageTexture definition.

HISTORY  New entity in IFC2x3.

IFC4 CHANGE  Data type of RasterCode has been corrected to BINARY.

8.12.3.1.1 Attributes

# Attribute Type Description
IfcPresentationItem
IfcSurfaceTexture
1 RepeatS IfcBoolean The RepeatS field specifies how the texture wraps in the S direction. If RepeatS is TRUE (the default), the texture map is repeated outside the [0.0, 1.0] texture coordinate range in the S direction so that it fills the shape. If RepeatS is FALSE, the texture coordinates are clamped in the S direction to lie within the [0.0, 1.0] range.
2 RepeatT IfcBoolean The RepeatT field specifies how the texture wraps in the T direction. If RepeatT is TRUE (the default), the texture map is repeated outside the [0.0, 1.0] texture coordinate range in the T direction so that it fills the shape. If RepeatT is FALSE, the texture coordinates are clamped in the T direction to lie within the [0.0, 1.0] range.
3 Mode OPTIONAL IfcIdentifier The Mode attribute is provided to control the appearance of a multi textures. The mode then controls the type of blending operation. The mode includes a MODULATE for a lit appearance, a REPLACE for a unlit appearance, and variations of the two.

> NOTE  The applicable values for the Mode attribute are determined by view definitions or implementer agreements. It is recommended to use the modes described in ISO/IES 19775-1.2:2008 X3D Architecture and base components Edition 2, Part 1. See [18.4.3 MultiTexture](http://www.web3d.org/x3d/specifications/ISO-IEC-19775-1.2-X3D-AbstractSpecification/Part01/components/texturing.html#MultiTexture) for recommended values.

> IFC4 CHANGE  New attribute replacing previous TextureType.
4 TextureTransformOPTIONAL IfcCartesianTransformationOperator2D The TextureTransform defines a 2D transformation that is applied to the texture coordinates. It affects the way texture coordinates are applied to the surfaces of geometric representation itesm. The 2D transformation supports changes to the size, orientation, and position of textures on shapes. Mirroring is not allowed to be used in the IfcCartesianTransformationOperator
5 Parameter OPTIONAL LIST [1:?] OF IfcIdentifier The Parameter attribute is provided to control the appearance of a multi textures. The applicable parameters depend on the value of the Mode attribute.

> NOTE  The applicable values for the list of Parameter attributes are determined by view definitions or implementer agreements. It is recommended to use the source and the function fields described in ISO/IES 19775-1.2:2008 X3D Architecture and base components Edition 2, Part 1. See [18.4.3 MultiTexture](http://www.web3d.org/x3d/specifications/ISO-IEC-19775-1.2-X3D-AbstractSpecification/Part01/components/texturing.html#MultiTexture) for recommended values.

> By convention, _Parameter[1]_ shall then hold the source value, _Parameter[2]_ the function value, _Parameter[3]_ the base RGB color for select operations, and _Parameter[4]_ the alpha value for select operations.

> IFC4 CHANGE  New attribute added at the end of the attribute list.
IsMappedBy SET [0:?] OF IfcTextureCoordinate FOR Maps Texture coordinates, either provided by a corresponding list of texture vertices to vertex-based geometric items or by a texture coordinate generator, that applies the surface texture to the surfaces of the geometric items.

> IFC4 CHANGE  New attribute added at the end of the attribute list.
UsedInStyles SET [0:?] OF IfcSurfaceStyleWithTextures FOR Textures
IfcBlobTexture
6 RasterFormat IfcIdentifier The format of the RasterCode often using a compression.
7 RasterCode IfcBinary Blob, given as a single binary, to capture the texture within one popular file (compression) format. The file format is provided by the RasterFormat attribute.

8.12.3.1.2 Entity inheritance

dot_inheritance IfcBlobTexture IfcBlobTexture IfcSurfaceTexture IfcSurfaceTexture IfcBlobTexture->IfcSurfaceTexture IfcImageTexture IfcImageTexture IfcImageTexture->IfcSurfaceTexture IfcPresentationItem IfcPresentationItem IfcSurfaceTexture->IfcPresentationItem IfcPixelTexture IfcPixelTexture IfcPixelTexture->IfcSurfaceTexture IfcPresentationItem_children 16 more... IfcPresentationItem_children->IfcPresentationItem

8.12.3.1.3 Formal representations

ENTITY IfcBlobTexture
 SUBTYPE OF (IfcSurfaceTexture);
	RasterFormat : IfcIdentifier;
	RasterCode : IfcBinary;
 WHERE
	SupportedRasterFormat : SELF.RasterFormat IN ['BMP', 'JPG', 'GIF', 'PNG'];
	RasterCodeByteStream : BLENGTH(RasterCode) MOD 8 = 0;
END_ENTITY;