# NAME

GDX_EXT_SURF - Extruded Surface

# GENERAL DESCRIPTION

A GDX Extruded Surface parametrically defines a linearly extruded surface using an extrusion vector and a curve to be extruded.

# DDF SPECIFICATION

    entity 14:0   GDX_EXT_SURF   "Extruded Surface" {

    double
    EXTRUDE_VEC[3];

    ptr
    GEN_CURVE
    reftype = (P_CURVES);

    double
    V_PARM;

    };

# FIELD DESCRIPTIONS

EXTRUDE_VEC

A 3D array containing the X, Y, and Z coordinates of the extrusion vector.

GEN_CURVE

The database pointer of the GDX curve corresponding to the curve to be extruded. 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
V_PARM

If This value is equal to -1, the surface is unbounded in V direction. If this value is greater than 0, it indicates that the surface is bounded with V_PARM itself as the upper bound on V.

# PARAMETERIZATION

Depending on the value of V_PARM, two types of parameterizations are allowed. as follows.

# PARAMETRIC RANGE

The GDX Extruded Surface is defined over the following parametric range: If v_parm < 0: -infinity <= v <= infinity u, same as the corresponding directrix if v_parm > 0: 0.0 <= v <= v_parm 0.0 <= u <= 1.0

# RESTRICTIONS

None.