How to make a selected face be truly flat

[DanRathbun]

@colin

Can I use the extension to help solve the big model problem one of our customers is having?

I have no objection to my lil’ part helping others. It’s why I posted it. It was basically just converting pseudo code description of the task into concise Ruby code as possible.

But it may suffer from the same “SketchUp has differing behavior” syndrome.
My lil method uses the API’s idea of parallel vectors (within the API tolerance) to decide if faces are coplanar. I seem to recall a topic thread on this that TT weighed in on. It was about the API’s lack of a “coplanar” test method for the API.

@tt_su

You’d have to erase the sharing edges - there is no explicit method for this. This means that if the faces aren’t truly co-planar they will be lost. Make sure you calculate the best fit plane for all the vertices and then check of all of them are on the plane. Comparing face normals will yield inaccurate result - something which I’ve seen people frequently do.

I think SW gets around this by first doing what TT suggests, so that by the time he calls my method the faces are truly coplanar, so the normal vector compare can be trusted.

@tt_su

@john_drivenupthewall

e.faces[0].normal.dot(e.faces[1].normal).abs > 0.9999999999999

Comparing the normal will fail with small features or close to degenerate faces.
To match what SketchUp to consider two faces coplanar you’d have to get best fit plane for all the vertices in the two faces and then check if they are all on the plane.

Something like this: TT::Geom3d.planar_points? (TT_Lib2, geom3d.rb, line 36)