IfcBlobTexture

IfcBlobTexture提供其映射到的曲面的照明参数的二维分布。纹理本身以单个二进制blob的形式给出，表示像素格式文件的内容。像素文件的文件格式由RasterFormat属性指定，允许的格式由where rule SupportedRasterFormat引导。

注意：特定于工具箱的二进制数据类型实现可能会限制二进制blob的最大长度，以捕获光栅文件内容。

有关纹理节点的解释，请参见IfcImageTexture definition。

IFC2x3中增加的新实体。

IFC4更改光栅代码的数据类型已更正为二进制。

Formal Propositions

Rule	Description
SupportedRasterFormat	Currently the formats of bmp, jpg, gif and pgn, shall be supported.
RasterCodeByteStream	The size of the raster code shall be a multiple of 8 bits.

 

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcPresentationItem
IfcSurfaceTexture
1	RepeatS	IfcBoolean	[1:1]	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.	X
2	RepeatT	IfcBoolean	[1:1]	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.	X
3	Mode	IfcIdentifier	[0:1]	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 for recommended values.	X
4	TextureTransform	IfcCartesianTransformationOperator2D	[0:1]	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	X
5	Parameter	IfcIdentifier	L[1:?]	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 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.	X
	IsMappedBy	IfcTextureCoordinate @Maps	S[0:?]	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.	X
	UsedInStyles	IfcSurfaceStyleWithTextures @Textures	S[0:?]		X
IfcBlobTexture
6	RasterFormat	IfcIdentifier	[1:1]	The format of the RasterCode often using a compression.	X
7	RasterCode	IfcBinary	[1:1]	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.	X

EXPRESS Specification

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;