What's the difference in these 2 files

Hi,

I’d like someone really knows the guts of SketchUp to have a look at these 2 files. I don’t know SketchUp (I’m a Rhino developer) very well myself but it seems like you ought to be able to use the push-pull tool on either of them. In Rhino they are both meshes in the xy plane with corners at 0,0,0 5,0,0 5,5,0 and 0,5,0. The only difference is the one that doesn’t work is a single quad that is turned into a single face in the SDK. The one that does work is 4 quads in Rhino that get turned into a single face with the SDK. The interior colinear vertices of the second example are getting removed so both faces in SU should only have the 4 corner vertexes. Thanks.

Cheers,
Tim

push_pull.skp (7.6 KB) no_push_pull.skp (7.7 KB)

There is in fact another difference.

The "no_push_pull.skp" face is really 2 coplanar faces separated with a softened diagonal edge.
Viz …

image

The example models units are set to Archetectural, fractional inches with length snapping at 1/16" of an inch. It would be best to switch off length snapping and set the units to Decimal millimeters so things are equal in SketchUp and Rhino.

Following up on @DanRathbun’s correct observations:

First please realize that when an edge is hidden in SketchUp, that edge still exists and still acts as a boundary to adjacent faces. So, the surface seen in your no_push_pull.skp is actually two triangular faces that have been visually joined into a surface by hiding the edge between them. You can see this if you turn on View->Hidden Geometry.

Second, please understand that SketchUp’s built-in pushpull operates only on a single face at a time. It can’t simultaneously pull the two triangles making up the surface.

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Thanks. That’s what I needed. I couldn’t tell that it was 2 triangles in SU. Since we can have non planar quads in Rhino I triangulate the mesh and then rejoin adjacent coplanar faces into an ngon which is what I feed the SKP SDK. I had a bug in my code where it didn’t realize an ngon had been created if it only contained 2 faces. So triangles were being sent to the SDK instead of the quad.

I do understand about pushpull only working on a single face. Until you enlightened me though that’s what I thought I had.

Tim

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