# Synopsis

PDX_MSGT gdx_GetNurbSurfIsoCurve(long option, MDA_PTR gdx_db_ptr, double uv_isoparm, int model, void *gdx_curve)

# Purpose

Extracts an iso-parametric curve from the GDX NURB Surface

# Description

Extracts an iso-parametric curve from the GDX NURB Surface entity as a GDX curve entity. The uv_isoparm value must be within the relimited domain of the GDX NURB Surface. By default, the uv_isoparm value indicates an iso-parm curve value at a constant V parameter value(a U iso-parametric curve). If an error occurs any data created during the conversion is deleted and no GDX curve is created. The GDX NURB Surface entity must be a valid GDX definition.

# Input

## option

### GDX_UVALUE

Get a V iso-parametric curve (uv_isoparm is a constant U parameter value).

### GDX_UNNORM

Unnormalize the constant parameter value

### GDX_COMMIT

Commit the entity to the database

### GDX_MAPCURVE

Map GDX NURB Curve to curve type

### GDX_NONRATTOPARMSPL

If the option GDX_MAPCURVE is specified, map non-rational NURBS curves to parametric splines

## gdx_db_ptr

The valid GDX NURB Surface entity database pointer

## uv_isoparm

The UV constant parameter value to extract the curve at

## model

The model to create the GDX curve in

# Output

## gdx_curve

The GDX curve entity database pointer or structure pointer

# Tolerances

          MODEL_SPACE_PNT_TOL
          ZERO_TOL
          TANGENT_TOL
          CURVATURE_TOL
          DERIVATIVE_TOL
          COLLINEAR_TOL
          .fi

# Return

          GDX_NOERR
          GDX_INVALIDMODEL
          GDX_PARMOUTOFRANGE
          Low level error return
          .fi