# 8.8.3.28 IfcRectangularPyramid

## 8.8.3.28.1 Semantic definition

The IfcRectangularPyramid is a Construction Solid Geometry (CSG) 3D primitive. It is a solid with a rectangular base and a point called apex as the top. The tapers from the base to the top. The axis from the center of the base to the apex is perpendicular to the base. The inherited Position attribute defines the IfcAxisPlacement3D and provides the location and orientation of the pyramid:

• SELF\IfcCsgPrimitive3D.Position: The location and orientation of the axis system for the primitive.
• SELF\IfcCsgPrimitive3D.Position.Location: The center of the circular area being the bottom face of the cone.
• SELF\IfcCsgPrimitive3D.Position.Position[3]: The z-axis of the inherited placement coordinate system provides the center axis of the IfcRightCircularCone, and the apex is at the Height value applied to the positive direction of the z-axis. The BottomRadius defines the circular base at the xy-plane of the placement coordinate system.

As shown in Figure 8.8.3.28.A, the pyramid is positioned within its own placement coordinate system. The origin is the center of the bottom rectangle, that lies in the XY plane. The apex lies on the positive z axis at [0, 0, Height].

Texture use definition

On each triangular side face, textures are aligned facing upright. Textures are stretched or repeated to the extent of the base of each face according to RepeatS. Textures are stretched or repeated towards the top point according to Repeat T, where the top point has coordinates of (0.5,1.0) if RepeatT is False.

On the bottom face, textures are aligned facing front-to-back.

Figure 8.8.3.28.B 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.

## 8.8.3.28.4 Formal representation

ENTITY IfcRectangularPyramid
SUBTYPE OF (IfcCsgPrimitive3D);
XLength : IfcPositiveLengthMeasure;
YLength : IfcPositiveLengthMeasure;
Height : IfcPositiveLengthMeasure;
END_ENTITY;