# Synopsis

PDX_MSGT gdx_ConvertRTSToSurface(long option, MDA_PTR gdx_rts_ptr, int model, double approx_tol, int *parm_chg_flg, MDA_PTR *gdx_surface_ptr)

# Purpose

Convert a GDX Rectangular Trimmed Surface entity to a GDX Surface entity

# Description

Create a bounded GDX Surface that represents the trimmed portion of a given GDX Rectangular Trimmed Surface entity. The GDX surface type is consistent with the underlying surface type of the RTS. For underlying analytical surfaces Cone, Torus, Sphere, and Cylinder, the GDX Surface will be of type Rev-Surface.

# Input

## option

Options (not used)

## gdx_rts_ptr

GDX Rectangular Trimmed Surface database pointer

## model

GDX model for entity creation

## approx_tol

Approximation tolerance in case the conversion is not precise. If ruled surface is trimmed in the v (linear) direction, then the boundary (new rail) curve(s) representing this trimming may not be precisely representable with any GDX entity type. Hence, approximation is required. The extracted ruled subsurface (S2(u,v)) should not deviate from the corresponding portion of the original surface (S1(u,v)) by more than approx_tol. That is, the projection distance from any point on S2(u,v) to S1(u,v) (or the reverse) should not exceed approx_tol. This tolerance corresponds to those in other GDX functions which do any type of curve/surface approximation. There is no corresponding gdx_tolerance; however approx_tol = 10 or 100 times MODEL_SPACE_PNT_TOL is a reasonable setting.

# Output

## parm_chg_flg

Flag indicating whether or not parameterization has changed. .nf = PDX_FALSE : parameterization has not changed = PDX_TRUE : parameterization has changed .fi

## gdx_surface_ptr

GDX Surface (untrimmed) database pointer

# Tolerances

          MODEL_SPACE_PNT_TOL
          COPLANAR_TOL
          TANGENT_TOL
          CURVATURE_TOL
          DERIVATIVE_TOL
          .fi

# Return

          GDX_NOERR
          GDX_ENTITYNOTCURVE
          Low level error return
          .fi