# Synopsis

PDX_MSGT igeo_EvalSurfaceProps(long option, MDA_PTR db_ptr, double u_val, double v_val, double uv_direction[2], IGEO_SURFACE_PROPS *props)

# Purpose

Evaluate properties of an IGES surface entity

# Description

At a given U, V parameter value between 0.0 and 1.0 inclusive, evaluate properties on the IGES surface entity. These properties include the 3D point location, tangent, and curvature at the specified parameter value.

# Input

## option

### IGEO_DIRECTCURV

Calculate the directional curvature based on the UV direction vector uv_direction

## db_ptr

The IGES surface entity database pointer

## u_val

The U parameter value to evaluate (0.0 - 1.0)

## v_val

The V parameter value to evaluate (0.0 - 1.0)

## uv_direction

The UV parameter space direction vector for the IGEO_DIRECTCURV option

# Output

## props

The surface properties at the evaluation parameter

# Return

          IGEO_NOERR
          Low level error return
          .fi