Snap to curves, points, or the grid

The snap modes “snap” or lock movement/placement of objects and points.

Snap to...	Hold	Or click
Curves, isoparametric curves, surface edges, or curves-on-surface. When the appropriate options are turned on, can snap to curve divisions, pivot points, or bounding box center, as well as curve intersections (true or projected).Also snaps to construction planes (see below).	+ (Windows) or + (Mac)
Grid intersections.	(Windows) or (Mac)
CVs, edit points, pivot points, locators.	(Windows) or (Mac)

Curve Snap Options

Click on the small arrow to the right of the icon to open a window with the following options.

Snap Divisions

You can use arc length snapping on curves (snap to the midpoint, 1/3, 1/4, etc) by setting Snap Divisions to avalue from 0 to 100. For example, setting this value to 2 and then using snap gives you a “snappable” point (shown as a light blue line segment) halfway along the curve.

Snap to Center

When this option is turned on and you click on a curve, the center of the curve’s bounding box is displayed as a small cross surrounded by a circle. Moving the cursor in close proximity of the center icon lets you snap to it.

Pivot

When this option is turned on and you click on a curve, its pivot is displayed. Moving the cursor in close proximity of the pivot icon lets you snap to it.

You can snap to both the scaling and rotation pivots (if they are not in the same location).

Projected Intersections

When this option is turned on, you can snap to the intersection points between curves in any orthographic or perspective view, even if the curves don’t truly intersect in world space. These intersection points are displayed as pink crosses.

Note

If the model contains a lot of geometry, snapping to projected intersections may take a few seconds to occur.

True Intersections

If this option is turned on, then:

snap will automatically snap to all intersections between free curves, surface edges, isoparms, curves on surface, and trim edges.
snap will automatically snap a new curve-on-surface (CoS) to CoS-CoS intersections on the same surface.

More features of Curve Snap curve

snap automatically snaps to the locations where the curve intersects a plane. The intersection points are shown as purple crosses.
If you click on the edge of a construction plane while curve snap is on, movement is constrained to that construction plane.
After snapping to a curve using + (Windows) or + (Mac), you can release the keys and movement will remain constrained to the curve.
Tip
When using curve snapping, you can release the hotkeys after the item has snapped to the curve, and the item will continue to stick to the curve as long as the mouse button is pressed.

Horizontal and vertical snapping

In orthographic windows, you can snap to the horizontal or vertical level of the thing you click, instead of its exact position:

Click the to snap to the horizontal position.
Click the to snap to the vertical position.

For example, you can line up three CVs along the same horizontal line without affecting their vertical positions:

Use Pick > Point Types > CV to pick the CVs.
Choose Transform > Move.
Hold (Windows) or (Mac) to turn on magnet snapping.
-click the CV you want to align with.

The picked CVs move to snap to the vertical position of the CV you clicked, but keep their own horizontal position.