# Synopsis

PDX_MSGT igeo_Approx126As112(long option, MDA_PTR db_ptr_126, EAM_STACK *stack, int model, double tolerance, int max_iters, MDA_PTR *db_ptr)

# Purpose

Approximate an IGES NURBS curve (126) as an IGES spline curve (112)

# Description

If the IGES NURBS curve is rational and/or degree greater than 3 the IGES NURBS curve is converted to an approximation of the IGES NURBS curve as non-rational and order less than 3. The non-rational degree 3 or less NURBS curve is then converted to the IGES 112 curve. By default the entity attribute matrix is concatenated with any matrix on the attribute stack and applied to the curve. All the original IGES NURBS curve non-pointer DE attributes are applied to the IGES parametric spline curve. If a conversion error occurs any data created during the conversion is deleted and no IGES parametric spline curve (112) is created. The IGES NURBS curve entity must be a valid IGES definition. The conversion is exact for a non-rational degree less than 4 IGES NURBS curve, otherwise the conversion is an approximation to tolerance.

# Input

## option

### IGES_NOMATRIX

Do not apply entity matrix to data

## db_ptr_126

The valid IGES 126 NURBS curve entity database pointer

## stack

The IGES entity attribute stack handle

## model

The model to create the IGES 112 curve in

## tolerance

The conversion approximation tolerance

## max_iters

The maximium iterations to allow for convergence to tolerance

# Output

## db_ptr

The IGES 112 curve entity database pointer

# Tolerances

          PNT_PROJ_TOL
          ANGLE_TOL
          ZERO_TOL
          .fi

# Return

          IGEO_NOERR
          IGEO_CURVENOTNURBS
          IGEO_NOMEMORY
          Low level error return
          .fi