# NAME

GDX_REV_SURF - Revolved Surface

# GENERAL DESCRIPTION

A GDX Revolved Surface parametrically defines a revolved surface using an axis of revolution (defined by a point and direction), a curve to be revolved, and start and end angles.

# DDF SPECIFICATION

    entity 13:0   GDX_REV_SURF   "Revolved Surface" {

    double
    REVOLVE_PNT[3];

    double
    REVOLVE_VEC[3];

    double
    START_ANGLE;

    double
    END_ANGLE;

    ptr
    GEN_CURVE
    reftype = (P_CURVES);

    };

# FIELD DESCRIPTIONS

REVOLVE_PNT

A 3D array containing the X, Y, and Z coordinates of a point on the axis of revolution.

REVOLVE_VEC

A 3D array containing the X, Y, and Z coordinates of the axis of revolution.

START_ANGLE

The start angle in radians.

END_ANGLE

The end angle in radians.

GEN_CURVE

The database pointer of the GDX curve corresponding to the curve to be revolved. The allowable GDX entity type/forms consists of the parametrically defined GDX curve entities as defined by the P_CURVES ptrlist variable in gdx.ddf. For reference, these entities are:

GDX_CONIC
GDX_NURB_CURVE
GDX_ARC
GDX_SPLINE_CURVE
GDX_POLYLINE
GDX_COMP_CURVE
GDX_OFFSET_CURVE
GDX_TRIM_CURVE

# PARAMETERIZATION

The parameterization is the same as that used for the IGES Surface of Revolution Entity (Type 120) and can be found in Section 4.16 of The Initial Graphics Exchange Specification (IGES) Version 5.2.

# PARAMETRIC RANGE

The GDX Revolved Surface is defined over the following parametric range: u0 <= u <= u1 START_ANGLE <= v <= END_ANGLE

       where u0 and u1 are parametric bounds of the curve to be revolved.

# RESTRICTIONS

The GDX Revolved Surface is subject to the following restrictions: START_ANGLE < END_ANGLE <= START_ANGLE + MTH_2_PI