move vertex on plane / face I'm being frustrated by this simple task: I want to move the marked vertex, but it's supposed to only move on its surface. Reason being, I want to subdivide the surface into a specific shape. ...Tried for hours, searched online for hours, just couldn't find it out. I assume its more simple than I think it is, but I just can't get it to work. Can you help me?

Thanks in advance!
Change your transform orientation from Global to Normal then grab the vertex with G and restrict it from the local normal Z-axis by holding Shift and pressing Z