# Synopsis

PDX_BOOL gdx_TestSurfContinuity(long option, double *cont_toler, int test_deriv, double (*deriv_rght)[GDX_MAX_DEG + 1][3], double (*deriv_left)[GDX_MAX_DEG + 1][3])

# Purpose

Test the surface derivative for continuity

# Description

Compares the surface derivatives for continuity. The derivatives are assumed to have been evaluated from the left and the right or from above and below. For the GDX_GTEST option the test for continuity is performed based on G continuity values if the test_deriv is <= 2, otherwise the derivatives are compared for continuity. The G1 continuity test is done with respect to the tangent plane normals.

Note that it is assumed that this function has already been called (and passed!) for continuity less than test_deriv.

# Input

## option

### GDX_GTEST

Test for G continuity up to test_deriv of 2

## cont_toler

The surface continuity tolerance. The distance between the derivatives must be less then or equal this value to have derivative continuity .nf [0] = Model space distance (G0) [1] = Radian angular difference (G1) [2] = Curvature difference (G2) [3] = Normalized derivative difference .fi

## test_deriv

The surface degree of the derivatives being tested

## deriv_rght

The derivative(s) calculated from the right or above

## deriv_left

The derivative(s) calculated from the left or below

# Tolerances

          ZERO_TOL
          NORMAL_MAG_TOL
          .fi

# Return

          PDX_TRUE - The derivatives are continuous within cont_toler
          PDX_FALSE - The derivatives are not continuous within cont_toler
          .fi