Opposition direction of Planerface.Normal

[thannaingoo.api]

Dear All,

How could I convert planerface.Normal to opposite direction.

Regards

Eden Oo

[aignatovich · Accepted solution]

Hi! Do you want to get the opposite direction? In such case just write -1*planerface.Normal or planerface.Normal.Negate(). But if you want to flip the face... it is not possible

[jeremytammik · Accepted solution]

Please always check your spelling. Otherwise, your thread might never be found by relevant later searches. This is about normals of planar faces represented by the PlanarFace class.

Here are some other threads relevant to this topic:

• https://forums.autodesk.com/t5/revit-api-forum/faces-of-the-room-from-solid-clockwise-and-counter-cl...
• https://forums.autodesk.com/t5/revit-api-forum/about-the-normal-of-a-mesh-triangle/m-p/8546140
• https://forums.autodesk.com/t5/revit-api-forum/incorrect-face-normal/m-p/7108787

I believe that, together, they answer all possible questions on face normals and mesh triangle orientation.

Note the tricky bits in the third discussion, explaining why you need to differentiate between:

• A picked face and the face returned by the element geometry.
• A face belonging to the symbol geometry (family definition coordinate space) and instance geometry (project coordinates).

Many thanks to @Revitalizer  and @FAIR59  for their analysis and illuminating explanations there!

Cheers,

Jeremy