Weird behaviour when making cockpit

[jph]

Hi! This is my first time posting here so hopefully it is appropriate.

I’m trying to learn Blender with the character creation course and have some strange behaviour:

All I wanted to do was move the point along the line to the left (double click G), but instead it goes down and behaves strangely. I can move it left by doing G+X but then I get other unwanted behaviour. Also, when I try to move it, it looks like there is another vertex below it? Is there a nice way to see if there are vertices on top of each other? My guess is that when I was creating the extrusion just above the vertex, I must have accidentally made several others? I also tried to use the knife tool to create the kind of shape you can see in the reference image (which I just found on the internet).

The same problem happens in several places, not just here (so I will probably scratch and restart, but I want to make sure I don’t do it again…).

[FedPete]

With pressing gg you can only move the vertice along the connected (via edges) vertices.
If it behaves strangely, you probably have a route using different paths (edges).

Your first image show orange lines but not from the selected vertice.
Edges color starting from the selected vertice is orange and the further away it darker becomes.
So I think you have double vertices. Meaning vertices occupying the same location.
Which can happen often by user error.

You need to merge vertices by distance!

In edit mode, go into vertice selection mode, press a to select all vertices.
Right mouse click for context-sensitive menu. “Merge vertices” > “Merge by distance”.

Try to change the range from 0.0001 to 0.1 to find out how many and which vertice are merged.
If succeeded then, try the thing you want to do!

Vertices duplication happens a lot when extruding and aborting this process!
Press e to extrude, then vertices are already copied on the same spot. Pressing escape or clicking. stops the process but with (invisible) vertices duplication. It is a good practice to check for duplicated vertices, by using the ‘merge by distance’ feature. There is no way to see, if vertices are on top of each other, except for look at the orange gradient of edges. and edge vertices relations. If you select a single edge, the two vertices (in vertice mode), will be organge. If not, check doubles!

[NP5]

That dotted white line means you are in GG mode, sliding a vertex only along one of its connected edges. It can sometimes be tricky to get a vert to go along the particular edge you want it to! Minds of their own at times.

As Fed Pete says. If you suspect you may have double verts then press A for select all and them M, by distance. If any duplicates have been made accidentally they ought to be right on top of one another and merge them away like that.

Alternatively, form a saved file position, just delete verts by hand, then remake the edges/faces you want with those left. Obviously, Ctrl Z undoing any that you delete and fine are not duplicates and you still want that vert.

[jph]

Thanks to both of you! Merging did the trick. The default distance of 0.0001 removed ten vertices which must have all been hiding.