The IfcBlock is a Construction Solid Geometry (CSG) 3D primitive. It is defined by a position and a positve distance along the three orthogonal axes. The inherited Position attribute has the IfcAxisPlacement3D type and provides:
The XLength, YLength, and ZLength attributes define the size of the IfcBlock along the three axes.
Figure 1 illustrates geometric parameters of a block where the block positioned within its own placement coordinate system. The values for XLength, YLength, and ZLength are applied to the positive direction of the X, Y, and Z axis.
Figure 1 — Block geometry
NOTE Definition according to ISO/CD 10303-42:1992
A block is a solid rectangular parallelepiped, defined with a location and placement coordinate system. The block is specified by the positive lengths x, y, and z along the axes of the placement coordinate system, and has one vertex at the origin of the placement coordinate system.
NOTE Entity adapted from block defined in ISO 10303-42.
HISTORY New entity in IFC2x3.
On each side face, textures are aligned facing upright. On the top and bottom faces, textures are aligned facing front-to-back. Textures are stretched or repeated to the extent of each face according to RepeatS and RepeatT.
Figure 2 illustrates default texture mapping with a clamped texture (RepeatS=False and RepeatT=False). The image on the left shows the texture where the S axis points to the right and the T axis points up. The image on the right shows the texture applied to the geometry where the X axis points back to the right, the Y axis points back to the left, and the Z axis points up.
Figure 2 — Block textures
|LayerAssignment||SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems||Assignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items.|
> IFC2x3 CHANGE The inverse attribute LayerAssignments has been added.
> IFC4 CHANGE The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed.
|StyledByItem||SET [0:1] OF IfcStyledItem FOR Item||Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.|
> IFC2x3 CHANGE The inverse attribute StyledByItem has been added.
|1||Position||IfcAxis2Placement3D||The placement coordinate system to which the parameters of each individual CSG primitive apply.|
|Dim||INVALID||The space dimensionality of this geometric representation item, it is always 3.|
|2||XLength||IfcPositiveLengthMeasure||The size of the block along the placement X axis. It is provided by the inherited axis placement through _SELF\IfcCsgPrimitive3D.Position.P_.|
|3||YLength||IfcPositiveLengthMeasure||The size of the block along the placement Y axis. It is provided by the inherited axis placement through _SELF\IfcCsgPrimitive3D.Position.P_.|
|4||ZLength||IfcPositiveLengthMeasure||The size of the block along the placement Z axis. It is provided by the inherited axis placement through _SELF\IfcCsgPrimitive3D.Position.P_.|
ENTITY IfcBlock SUBTYPE OF (IfcCsgPrimitive3D); XLength : IfcPositiveLengthMeasure; YLength : IfcPositiveLengthMeasure; ZLength : IfcPositiveLengthMeasure; END_ENTITY;