IfcBlock

BACnet MVD

#### IfcBlock

Natural language names

| Quader
| Block
| Parallélépipède

##### Semantic definitions at the entity

Entity definition

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:

- SELF\IfcCsgPrimitive3D.Position: The location and orientation of the axis system for the primitive.
- SELF\IfcCsgPrimitive3D.Position.Location: The block has one vertex at location and the edges are aligned with the placement axes in the positive sense.

The XLength, YLength, and ZLength attributes define the size of the IfcBlock along the three axes.

| Figure 276 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 276 — 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.

Texture definition

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 277 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.

Side | Normal | Origin X | Origin Y | Origin Z | S Axis | T Axis
--- | --- | --- | --- | --- | --- | ---
Left | -X | 0 | +YLength | 0 | -Y | +Z
Right | +X | +XLength | 0 | 0 | +Y | +Z
Front | -Y | 0 | 0 | 0 | +X | +Z
Back | +Y | +XLength | +YLength | 0 | -X | +Z
Bottom | -Z | 0 | +YLength | 0 | +X | -Y
Top | +Z | 0 | 0 | +ZLength | +X | +Y

Figure 277 — Block textures

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
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[1]. | X | X
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[2]. | X | X
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[3]. | X | X

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
IfcRepresentationItem

LayerAssignment

IfcPresentationLayerAssignment
@AssignedItems

S[0:1]

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.

X

StyledByItem

IfcStyledItem
@Item

S[0:1]

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.

X

X

IfcGeometricRepresentationItem
IfcCsgPrimitive3D
1 | Position | IfcAxis2Placement3D |  | The placement coordinate system to which the parameters of each individual CSG primitive apply. | X | X
| Dim :=3 | IfcDimensionCount |  | The space dimensionality of this geometric representation item, it is always 3. | X | X
IfcBlock
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[1]. | X | X
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[2]. | X | X
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[3]. | X | X

##### Examples

- CSG primitive

##### Formal representations

XML Specification
`<xs:element name="IfcBlock" type="ifc:IfcBlock" substitutionGroup="ifc:IfcCsgPrimitive3D" nillable="true"/>
<xs:complexType name="IfcBlock">
<xs:complexContent>
<xs:extension base="ifc:IfcCsgPrimitive3D">
<xs:attribute name="XLength" type="ifc:IfcPositiveLengthMeasure" use="optional"/>
<xs:attribute name="YLength" type="ifc:IfcPositiveLengthMeasure" use="optional"/>
<xs:attribute name="ZLength" type="ifc:IfcPositiveLengthMeasure" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcBlock
SUBTYPE OF (IfcCsgPrimitive3D);
XLength : IfcPositiveLengthMeasure;
YLength : IfcPositiveLengthMeasure;
ZLength : IfcPositiveLengthMeasure;
END_ENTITY;

EXPRESS-G diagram

`

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