I’m a newbie but I’ve been building this model and keep getting these weird invisible lines that are messing up my polygons - they seem to occur when I create a shape and make it intersect with the rest of the model. But I don’t know how to fix this, I can’t figure out what this phenomenon is called, so I thought the best thing would be to upload a screenshot and see if anyone can point me in the right direction? Thank you so much!
Those are hidden edges, as you can confirm by changing the setting of View->Hidden Geometry on and off. They occur either when you explicitly hide an edge or when SketchUp determines that the vertices defining an area are not co-planar, hence can’t be covered by a single planar face. So, it breaks the face into a collection of smaller faces joined by hidden/softened/smoothed edges. You also have some hidden edges wandering off into space. Without watching you build the model, I can’t tell you exactly how you got those, but they are vestigial and can safely be erased.
Triangluation happens fairly often when you paste or create a round shape onto a pre-existing face, as shown in this screenshot
The edges of the circle intrude onto the edge of the face, causing SketchUp to think it needs to triangulate the adjacent faces. It is possible they really do intrude, in which case you need to redraw and prevent this from happening. It is also possible that SU decided it needed to triangulate in the middle of your editing and then failed to clean up the hidden edges when it turned out the face was after all still planar. Occasionally SU’s cleanup misses such temporary lines. You can check whether the face really isn’t planar by viewing hidden lines and then deleting them. If a face disappears, the hidden line was really needed because the remaining vertices aren’t planar. If nothing happens to the face, you ran into this known SU glitch.
THANK YOU so much! This just saved me so much time. Much appreciated Sketchup sage!