When it comes to push pull I understand that it does depend upon the winding (clockwise or counter clockwise) of the polygon. This is consistent and repeatable.
However, with an extrusion that has a closed polyline as a path it is not repeatable. I can guarantee that the points for the face are always created exactly the same way - since they come out of a txt file. I store x and y points at 1/10000 decimal inches. The z values are set as 1/2 of the height of the door panel.
I also calculate the path as x and y points which is a closed polyline. The Y values are 0.
face = group.entities().add_face(face_pts)
path = group.entities().add_curve(path_pts)
face.followme(path)
If I build the door at [0,0,0] look at it and then do a ctrl_z and repeat this process, I get a results where the the extrusion is sometimes reversed and sometimes not.
It appears random - although the polyline and face are always created exactly the same way.
When I create my curved stair stringers using fill_from_mesh I store each polygon's points with a clockwise winding. So far this has proved 100% predictable and repeatable.
In the early days I used to do a lot of work with GIS and Windows GDI and create polypolygon this way. If you wanted to create a continent with a large lake that has an island that has a body of water you would have a series of 4 diminishing polygons each completely residing within each other. The outer most polygon would be clockwise (the continent) the large lake would be counter clockwise, the island would be clockwise and the body of water in the island would be counter clockwise.
I found that the sketchup works essentially the same way with meshes.
