Face.ComputeDerivatives

Public Class

Returns the first partial derivatives of the underlying surface at the specified point.

Namespace: Autodesk.Revit.DB

Assembly: RevitAPI (in RevitAPI.dll) Version: 25.0.0.0 (25.0.0.0)

Syntax

public Transform ComputeDerivatives(
  UV point
)

Parameters

point UV

The parameters to be evaluated, in natural parameterization of the face.

Return Value

Transform
A transformation containing tangent vectors and a normal vector.

Remarks

The following is the meaning of the transformation members:

• Origin is the point on the face (equivalent to Evaluate(UV));
• BasisX is the tangent vector along the U coordinate (partial derivative with respect to U).
• BasisY is the tangent vector along the V coordinate (partial derivative with respect to V).
• BasisZ is the underlying surface’s normal vector. This is not necessarily aligned with the normal vector pointing out of a solid that contains the face, to get that value use ComputeNormal(UV).

None of the vectors are normalized.