Synopsis

PDX_MSGT gdx_ExtractSubIsoCurve(long option, MDA_PTR gdx_surf_ptr, int model, double iso_parm, double parm1, double parm2, double tolerance, int max_iters, MDA_PTR *gdx_crv_ptr)

Purpose

Extract a portion of an iso-parametric curve from a GDX surface.

Description

This routine extracts a portion of an iso-parametric curve from a GDX surface. The GDX iso-parametric curve is the type of curve that represents the surface in the particular iso-parametric direction. The exception is for the interior of a ruled surface and the offset surface iso-parametric curves which are approximated as GDX NURB curves. if parm1 > parm2, the portion of the desired iso curve is reversed.

Input

option

GDX_UVALUE

If set, then iso_parm is a u-value (isocurve is varying in v); otherwise, iso_parm is a v-value (isocurve is varying in u).

gdx_surf_ptr

The input surface database pointer from which a curve is to be extracted.

model

The GDX model to create the GDX iso curve in

iso_parm

A u- or v-value (see option). This defines which curve is to be extracted.

parm1

Desired parameter value that the iso curve is to start.

parm2

Desired parameter value that the iso curve is to end.

tolerance

The tolerance used to approximate the offset surface iso-parametric curve.

max_iters

The maximium iteration count to test for convergence for approximation

Output

gdx_crv_ptr

The extracted iso sub curve db_ptr.

Tolerances

      MODEL_SPACE_PNT_TOL
      PARM_SPACE_PNT_TOL
      COPLANAR_TOL
      ZERO_TOL
      KNOT_TOL
      PNT_PROJ_TOL
      ANGLE_TOL
      .fi

Return

      GDX_INVALIDPARMRANGE
      GDX_NOERR
      Low level error return
      .fi