Hi, I am confused with coordinate systems:
(1) From GeometryInstance.Transform property, we can get the norm = Transform.basisX, this normal is based on the document coordinate system, is that right? But some code shows that, we should do transform to get normal vector based on document systems.
(2) ComputeDerivatives of Face class, the normal and tangent vectors are based on the document coordinate system? Is that the instance coordinate system the same as the document coordinate system? For example, see following code
Autodesk.Revit.DB.XYZ FaceNormal = m_face.ComputeDerivatives(endptUV).BasisZ;
FaceNormal = reference.GetInstanceTransform().OfVector(FaceNormal); // transformation to get document coordinates instead of the parent symbol
I am confused (a) the coordinate system in Revit, and (b) whether I need to do additional transform of vectors calcualted by ComputeDerivatives() to document coordinate system?
