IfcRightCircularCone

Definition from ISO/CD 10303-42:1992: A right circular cone is a CSG primitive in the form of a cone. It is defined by an axis, a point on the axis, (...) and a distance giving the location along the axis from the point to the base of the cone. In addition, a radius is given (...).

Definition from IAI: In contrary to the ISO/CD 10303-42 definition, the IfcRightCircularCone may not be truncated. It provides:

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 cylinder.
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.


The cone is positioned within its own placement coordiante system. The origin is the center of the bottom circular disk, that lies in the XY plane. The apex lies on the positive z axis at [0, 0, Height].
When a texture is applied to the sides of the cone, the texture wraps counterclockwise (from above) starting at the back of the cone. The texture has a vertical seam at the back in the X=0 plane, from the apex (0, 0, Height) to the point (0, BottomRadius, 0). For the bottom cap, a circle is cut out of the texture square centred at (0, 0, 0) with dimensions (2 × BottomRadius) by (2 × BottomRadius). The bottom cap texture appears right side up when the top of the cone is rotated towards the -Z-axis. Texture Transform affects the texture coordinates of the Cone. NOTE see the Extensible 3D (X3D) definition for textures, please note, that all extrusions in IFC are into the positve z axis, whereas in X3D there are into the positive y axis, and the IFC cone is positioned at the bottom face, whereas in X3D it is positioned centric..

NOTE Corresponding STEP entity: right_circular_cone, the position attribute has been promoted to the immediate supertype IfcCsgPrimitive3D. No semi_angle attribute, and the radius defines the bottom radius, since only a non-truncated cone is in scope. Please refer to ISO/IS 10303-42:1994, p. 176 for the final definition of the formal standard.

HISTORY New entity in IFC2x Edition 3.

EXPRESS specification:

ENTITY IfcRightCircularCone

SUBTYPE OF (

IfcCsgPrimitive3D);

Height

IfcPositiveLengthMeasure;

BottomRadius

IfcPositiveLengthMeasure;

END_ENTITY;

Attribute definitions:

Height	:
BottomRadius	:

Inheritance graph

ENTITY IfcRightCircularCone;

ENTITY IfcRepresentationItem;

INVERSE

LayerAssignments

SET OF IfcPresentationLayerAssignment FOR AssignedItems;

StyledByItem

SET [0:1] OF IfcStyledItem FOR Item;

ENTITY IfcGeometricRepresentationItem;

ENTITY IfcCsgPrimitive3D;

Position

IfcAxis2Placement3D;

DERIVE

Dim

IfcDimensionCount := 3;

ENTITY IfcRightCircularCone;

Height

IfcPositiveLengthMeasure;

BottomRadius

IfcPositiveLengthMeasure;

END_ENTITY;