IfcCartesianTransformationOperator3D

Definition from ISO/CD 10303-42:1992: A Cartesian transformation operator 3d defines a geometric transformation in three-dimensional space composed of translation, rotation, mirroring and uniform scaling. The list of normalised vectors u defines the columns of an orthogonal matrix T. These vectors are computed from the direction attributes axis1, axis2 and axis3 by the base axis function. If |T|= -1, the transformation includes mirroring.

NOTE: Corresponding STEP entity : cartesian_transformation_operator_3d, please refer to ISO/IS 10303-42:1994, p. 33 for the final definition of the formal standard.

HISTORY: New entity in IFC Release 2x.

EXPRESS specification:

ENTITY IfcCartesianTransformationOperator3D

SUPERTYPE OF

(IfcCartesianTransformationOperator3DnonUniform)

SUBTYPE OF (

IfcCartesianTransformationOperator);

Axis3

OPTIONAL IfcDirection;

DERIVE

LIST [3:3] OF IfcDirection := IfcBaseAxis(3,SELF\IfcCartesianTransformationOperator.Axis1,
SELF\IfcCartesianTransformationOperator.Axis2,Axis3);

WHERE

WR1	:	SELF\IfcCartesianTransformationOperator.Dim = 3;
WR2	:	NOT(EXISTS(SELF\IfcCartesianTransformationOperator.Axis1)) OR (SELF\IfcCartesianTransformationOperator.Axis1.Dim = 3);
WR3	:	NOT(EXISTS(SELF\IfcCartesianTransformationOperator.Axis2)) OR (SELF\IfcCartesianTransformationOperator.Axis2.Dim = 3);
WR4	:	NOT(EXISTS(Axis3)) OR (Axis3.Dim = 3);

END_ENTITY;

Attribute definitions:

Axis3	:	The exact direction of U[3], the derived Z axis direction.
U	:	The list of mutually orthogonal, normalised vectors defining the transformation matrix T. They are derived from the explicit attributes Axis3, Axis1, and Axis2 in that order.

Formal Propositions:

WR1	:	The coordinate space dimensionality of this entity shall be 3.
WR2	:	The inherited Axis1 should have (if given) the dimensionality of 3.
WR3	:	The inherited Axis2 should have (if given) the dimensionality of 3.
WR4	:	The Axis3 should have (if given) the dimensionality of 3.

Inheritance graph

ENTITY IfcCartesianTransformationOperator3D;

ENTITY IfcRepresentationItem;

INVERSE

LayerAssignments

SET OF IfcPresentationLayerAssignment FOR AssignedItems;

StyledByItem

SET [0:1] OF IfcStyledItem FOR Item;

ENTITY IfcGeometricRepresentationItem;

ENTITY IfcCartesianTransformationOperator;

Axis1

OPTIONAL IfcDirection;

Axis2

OPTIONAL IfcDirection;

LocalOrigin

IfcCartesianPoint;

Scale

OPTIONAL REAL;

DERIVE

Scl

REAL := NVL(Scale, 1.0);

Dim

IfcDimensionCount := LocalOrigin.Dim;

ENTITY IfcCartesianTransformationOperator3D;

Axis3

OPTIONAL IfcDirection;

DERIVE

LIST [3:3] OF IfcDirection := IfcBaseAxis(3,SELF\IfcCartesianTransformationOperator.Axis1,
SELF\IfcCartesianTransformationOperator.Axis2,Axis3);

END_ENTITY;