# NAME

GDX_TORUS - Toroidal Surface

# GENERAL DESCRIPTION

A GDX Toroidal Surface (GDX Torus) parametrically defines a torus using a center point, major and minor radii, axis vector, and reference vector.

# DDF SPECIFICATION

    entity 19:0   GDX_TORUS   "Toroidal Surface" {

    double
    CENTER[3];

    double
    AXIS_VEC[3];

    double
    REF_VEC[3];

    double
    MAJ_RADIUS;

    double
    MIN_RADIUS;

    };

# FIELD DESCRIPTIONS

CENTER

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

AXIS_VEC

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

REF_VEC

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

MAJ_RADIUS

The distance (R) from the circle being revolved to the axis of revolution.

MIN_RADIUS

The radius (r) of the circle being revolved.

# PARAMETERIZATION

The parameterization is the same as that used for the IGES Toroidal Surface Entity (Type 198) and can be found in Appendix G.14 of The Initial Graphics Exchange Specification (IGES) Version 5.2.

# PARAMETRIC RANGE

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

# IMPLICIT EQUATION

The GDX Torus has the following implicit equation: S(x,y,z) = x*x + y*y + z*z - 2*R*SQRT(x*x + y*y) - r*r + R*R = 0

# RESTRICTIONS

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