Unable to use Knife tool for cutting IRIS of an eye?

Support Modeling
1

I was trying out an old tutorial where I am trying to add a loop using knife tool to the triangle area of the Iris of a UV sphere.

Knife tool is just not working. in the tutorial it shows to select the vertices, press 3 to go right view and then cut the vertices from middle.

I am trying that and pressing enter/spacebar and the vertices are not being cut, instead the ones which are not selected are being added with a loop.

Normal ctrl +r is not working on the triangle vertices.

What should I do?

knife-problem.jpg1578×759 258 KB

2

You can select the edges to cut and use Shift+K to cut only selected edges (press Z to cut all th way through and Enter to accept). Ensure no double vertices etc.
Alternatively select the edges and W / subdivide, then use edge slide to move the new edge to where you want it

Ctrl+R won’t work because you don’t have an edge loop with triangles

Supply a link to a blend file

3

Thanks it worked.