# What is difference between merge at center and scale along axis = 0 for 3 vertex which are collinear?

I performed an operation where I selected 3 collinear vertices and scale x=0. Then I performed the loop cut and it worked as desired but when I used merge - at center command, I was not able to perform loop cut correctly. What difference does it make? Ultimately both resulted in same geometry without distorting geometry... see images below. Image below shows vertices on which operation will be performed.

Below image shows loop cut creation after using "merge at center" Below image shows, scale along Y-axis = 0 value and then loop cut was performed and see how it extends upto tip.

## 1 Answer

If you scale 0 on X, it will make the vertices overlap but they are still separate vertices, there are not merged into one, you can still select one vertex and move it away. It's exactly as if you still had a quad except the tip is not visible anymore (see image below, except I kept the vertices a bit away from each other). With this topology you can still do a loop cut, loop cuts are only possible through quads:

If you merge the vertices with an M, you end up with only one vertex, like the topology below. Blender can't create a loop cut through this face as it doesn't know what edge it is supposed to cut next, loop cuts only work through quads, not tris like here (or ngons):

• you are right...I didn't count the vertices by going in x-ray when I scaled them to 0..hence the confusion...thank you as always for your brief explanation :) :) Commented Dec 11, 2021 at 16:58