I would like to transform a circle in a zigzag shape in only one direction, either horizontal or vertical - not both. The zigzag effect does it in all directions. Can I change it somehow? Or is there another option. Like this:
Anchors are inserted (Object > Path > Add anchor points)
Some anchors are moved up or down. Select an anchor point with the direct selection tool and move it. Hold shift key just after starting the motion => the direction is limited to vertical or horizontal. You can also tick with the arrow keys. Set a good arrow key increment in the preferences.