# NAME

GDX_POLYLINE - Polyline Curve

# GENERAL DESCRIPTION

A GDX Polyline (GDX Polyline) Curve represents a piecewise linear curve. The GDX Polyline is defined by a set of n 3D points that form a set of n-1 piecewise linear segments in a connected path starting with the first point and ending with the last point.

# DDF SPECIFICATION

    entity 4:0  GDX_POLYLINE   "Polyline Curve" {

    char
    PLANAR;

    char
    XY_PLANAR;

    char
    CLOSED;

    count
    NUM_OF_PNTS;

    double
    POINTS[NUM_OF_PNTS][3];

    double
    PLANE_NORMAL[3];

    };

# FIELD DESCRIPTIONS

PLANAR

Flag indicating whether or not the curve is planar. Note that if the curve is linear it is not considered to be planar as it is contained in an infinite number of different planes.

PDX_TRUE

The curve is planar.

PDX_FALSE

The curve is not planar.

XY_PLANAR

Flag indicating whether or not the curve lies in the Z = 0.0 plane.

PDX_TRUE

The curve lies in the Z = 0.0 plane.

PDX_FALSE

The curve does not lie in the Z = 0.0 plane.

CLOSED

Flag indicating whether or not the curve is closed.

PDX_TRUE

The curve is closed.

PDX_FALSE

The curve is not closed.

NUM_OF_PNTS

The total number of points in the polyline.

POINTS

The set of 3D coordinates (X, Y, Z) that define the end points of the linear segments that make up the GDX Polyline.

PLANE_NORMAL

The 3D coefficients of the normal vector to the plane of the curve if the curve is planar. If non-planar, these values should be set to 0.0 and will be ignored.

# PARAMETERIZATION

The parameterization is the same as that used for the IGES Copious Data Entity (Type 106) and can be found in Section 4.6 of The Initial Graphics Exchange Specification (IGES) Version 5.2.

# PARAMETRIC RANGE

The GDX Polyline curve is defined over the following parametric range: 0 <= u <= NUM_OF_PNTS - 1

# RESTRICTIONS

The GDX Polyline is subject to the following restrictions: NUM_OF_PNTS >= 1