# NAME

GDX_CYLINDER - Cylindrical Surface

# GENERAL DESCRIPTION

A GDX Cylindrical Surface (GDX Cylinder) parametrically defines a right circular cylinder using a point on the axis of the cylinder, the radius, an axis vector, and a reference vector.

# DDF SPECIFICATION

    entity 16:0   GDX_CYLINDER   "Cylindrical Surface" {

    double
    CENTER[3];

    double
    AXIS_VEC[3];

    double
    REF_VEC[3];

    double
    RADIUS;

    double
    TOP_PARM;

    };

# FIELD DESCRIPTIONS

CENTER

A 3D array containing the X, Y, and Z coordinates of the center of the GDX Cylinder.

AXIS_VEC

A 3D array representing the unitized axis direction of the GDX Cylinder. Corresponds to the z direction in the parameterization of the GDX Cylinder.

REF_VEC

A 3D array representing the unitized reference direction of the GDX Cylinder. Corresponds to the x direction in the parameterization of the GDX Cylinder. This vector should be perpendicular to the AXIS_VEC.

RADIUS

The radius (R) of the GDX Cylinder.

TOP_PARM

This value is for internal use only. If a GDX Cylinder entity is created without using functions in the gcr subsystem, this value should be set to -1 (indicates the entity is not locally bound).

# PARAMETERIZATION

The parameterization is the same as that used for the IGES Right Circular Cylindrical Surface Entity (Type 192) and can be found in Appendix G.11 of The Initial Graphics Exchange Specification (IGES) Version 5.2.

# PARAMETRIC RANGE

The GDX Cylinder is defined over the following parametric range: 0.0 <= u <= MTH_2_PI -infinity <= v <= infinity

# IMPLICIT EQUATION

The GDX Cylinder has the following implicit equation: S(x,y,z) = x*x + y*y + - R*R = 0

# RESTRICTIONS

The GDX Cylinder is subject to the following restrictions: R > 0.0