Bug in Alias 2018 API AlCurve

[Anonymous]

Hello,

when I was creating Nurbs Curves from the Alias API I came across a wrong function signature:

statusCode AlCurve::create( int deg, curveFormType form, int numKnots, const double knotVector[], int numControlPts, const double controlPoint[][4], const int multiplicity[])

The problem here is the signature for the controlPoints, it is defined as as two dimensional double array. But when you create the array in a C++ correct way:

    double **alControlPoints = (new double*[numControlPts]);
    for (int i = 0; i < numControlPts; i++)
    {
        alControlPoints[i] = new double[4];
        alControlPoints[i][0] = controlPoints[i][0];
        alControlPoints[i][1] = controlPoints[i][1];
        alControlPoints[i][2] = controlPoints[i][2];
        alControlPoints[i][3] = controlPoints[i][3];
    }

And then pass alControlPoints the the create function, the function will not succeed but return a wrong argument error.

The actual correct way to create the control points buffer is:

    double *alControlPoints = (new double[numControlPts * 4]);
    unsigned long long vertexIndex = 0;
    for (int i = 0; i < numControlPts; i++)
    {
        alControlPoints[vertexIndex++] = controlPoints[i][0];
        alControlPoints[vertexIndex++] = controlPoints[i][1];
        alControlPoints[vertexIndex++] = controlPoints[i][2];
        alControlPoints[vertexIndex++] = controlPoints[i][3];
    }

When you pass this to the create function, then it will work, but you need to make an ugly cast:

(double(*)[4]) alControlPoints

Therefore the signature for the create function should be
double controlPoints[]

If you compare it with the create function for the AlSurface, it already uses the correct signature.

Best regards,

Timo

[bob55 · Accepted solution]

Thank you for the heads up.  A ticket has been created for the issue.