Find the normal of surface

[supriya_chaugule]

Hiii.....I am trying to get the normal of each face of this model

public static UnitVector GetFaceNormal(Face inputFace,PartDocument doc)
{
Inventor.TransientGeometry tg = mApplication.TransientGeometry;

SurfaceEvaluator eval = inputFace.Evaluator;

// Get the center of the parametric range.
double[] center = new double[2];
center[0] = (eval.ParamRangeRect.MinPoint.X + eval.ParamRangeRect.MaxPoint.X) / 2;
center[1] = (eval.ParamRangeRect.MinPoint.Y + eval.ParamRangeRect.MaxPoint.Y) / 2;

bool status = eval.IsParamOnFace[ref center];

// Calculate the normal.
double[] normal = new double[3];
eval.GetNormal(center, normal);

// Create a unit vector to pass back the result.
UnitVector faceNormal = mApplication.TransientGeometry.CreateUnitVector(normal[0], normal[1], normal[2]);

return faceNormal;
}

But every time I got normal as (0,0,0) .Any suggestion on how can I get correct normal? 

[WCrihfield · Accepted solution]

Hi @supriya_chaugule.  I am not sure why you may be attempting to find the center point on each face, but I suspect that the center point of at least two of the faces on that part will not be a point 'on' the face, but over the big hole through the part.  Have you tried using the parameters from the Face.PointOnFace (a Point object) instead of the faces center?  Or maybe use the GetNormalAtPoint method, instead of the regular GetNormal method.  The GetNormalAtPoint method allows you to input the actual 3D Point X, Y,& Z coordinates to use.  It says that the point must be 'on' the surface though.

[supriya_chaugule]

Thank you @WCrihfield Its working with getNormLAtPoint method.