# -OSNAP in AutoCAD

> How AutoCAD's object snaps work: -OSNAP (-OS) sets the running modes, F3 turns them on and off, and END, MID or Shift + right-click force one. Try it free.

Object snaps put a pick exactly on a point of an object: an end, a midpoint, a centre. With object snapping on, the cursor near such a point shows its marker, in green, and its name in a tooltip; a click then lands on that point, not where the cursor is. The running snaps are the modes at work at every point prompt: at first Endpoint, Center, Intersection and Extension, as in AutoCAD. F3 turns object snapping on and off, writing `<Osnap on>` or `<Osnap off>`, and so does the Object snap button on the status bar, whose menu has a check box for each mode. With several snaps under the cursor, the nearest wins, and Tab cycles through the others. Ortho, Polar and snap mode never bend a snapped point.

-OSNAP sets the running snaps at the command line. It lists the modes running now, then asks for a list of modes: each by its capitals, separated with commas, as in `END,MID,CEN`, or `_END,_MID` in any language of AutoCAD. The list replaces the running set and turns object snapping on; `NONe`, `OFF` or Enter alone clears it. A mode it does not know gets `Invalid object snap modes.`, and the question again. Typed with an apostrophe, `'-OSNAP`, it works inside another command. The running snaps last until the page is reloaded, then they are AutoCAD's four again: like AutoCAD, the drawing does not keep them.

For one point only, override them: type a mode's capitals at a point prompt, `MID` or `_MID`, or hold Shift and right-click to choose it from a menu. That snap alone is looked for, whatever runs, and only for that point; one that finds nothing refuses the point and asks again. Typed by its capitals, `NONe` turns snapping off for one point. The same menu offers `FROM`: a base point, then an offset from it, so `@10,0` is 10 to its right.

- **Command:** `-OSNAP`
- **Aliases:** `-OS`
- **Panel:** [Inquiry & view](https://mellowcad.com/docs/commands.md#inquiry)
- **Try it:** [Open the editor](/draw), type `-OS` and press Enter.

## At the command line

The engine draws it and writes its history as you would type it: the prompts in AutoCAD 2027's order, with the same option letters.

-OSNAP sets Midpoint and Center as the running snaps; LINE then goes from an edge's midpoint to the circle's centre, and the top edge shows its Midpoint marker.

```text
Command: -OSNAP
Current osnap modes: End,Cen,Int,Ext
Enter list of object snap modes: _MID,_CEN
Command: LINE
Specify first point:
Specify next point or [Undo]:
```

## Options

### `ENDpoint` (`END`)

The nearest end of a line, an arc, a polyline segment, an elliptical arc or a spline: a rectangle's corners, a polygon's vertices. Its marker is a square.

### `MIDpoint` (`MID`)

Halfway along a line, an arc, a polyline segment, an elliptical arc or a spline. A triangle.

### `CENter` (`CEN`)

The centre of a circle, an arc or a polyline's arc. Pass the cursor over the curve itself: at the centre there is nothing to catch. A circle.

### `QUAdrant` (`QUA`)

The points of a circle or an arc at 0°, 90°, 180° and 270°, along the UCS's X and Y, and an ellipse's axis ends. A diamond.

### `INTersection` (`INT`)

Where two objects cross, or where a polar tracking path crosses an object. A cross.

### `EXTension` (`EXT`)

Past the end of a line, an arc or a polyline's straight segment: pass the cursor over the end, then move away along the object's line. A dashed path shows from the end, and a distance typed runs along it. A plus.

### `INSertion` (`INS`)

The point a text, an attribute definition or a block reference hangs from.

### `PERpendicular` (`PER`)

The foot of the perpendicular from the last point onto a line, past its ends too, a circle, an arc or a polyline segment. At [`LINE`](https://mellowcad.com/docs/commands/line.md)'s first point it waits for the next point: the line leaves the object square to it. A right angle.

### `TANgent` (`TAN`)

The point of a circle or an arc where a line from the last point touches it. At [`LINE`](https://mellowcad.com/docs/commands/line.md)'s first point it waits for the next point: the line leaves the curve tangent to it. A circle with a bar.

### `NEArest` (`NEA`)

The point of an object nearest the cursor. An hourglass.

### `APPint` (`APP`)

Apparent Intersection: where two objects cross in the view, though they are at different heights; where they truly meet, it is their intersection.

### `PARallel` (`PAR`)

Hold the cursor over a line for a moment, then move along its direction from the last point: a path parallel to the line holds the next point.

### `NONe` (`NON`)

No running snaps: object snapping finds nothing until a mode is set again.

### `OFF`

The same as `NONe`: the running set is cleared.

## What it does not do yet

The Drafting Settings dialog that OSNAP and OS open in AutoCAD: here they are unknown commands, and the status bar's menu sets the modes. Node and Geometric Center, as modes and in the menus. Mid Between 2 Points, the temporary track point and the keys held down for a one-point snap (Shift + A, Shift + Q…). Intersection, Perpendicular and Tangent on ellipses, Perpendicular and Tangent on splines, and Extension from a polyline's arc end, or with its distance and angle in the tooltip. A Perpendicular or a Tangent that waits for the other point at the start of a command other than [`LINE`](https://mellowcad.com/docs/commands/line.md) and [`CIRCLE`](https://mellowcad.com/docs/commands/circle.md). The aperture and marker settings, APERTURE and AUTOSNAP.

[What it does and still lacks, in detail (in English)](https://github.com/ovelilla/mellowcad/blob/main/docs/coverage/drafting-aids.md#-osnap---os--es--refent---ref--pt-br--osnap---os)

## Questions

### What is the OSNAP command in AutoCAD?

In AutoCAD, OSNAP (`OS`) opens the Drafting Settings dialog at its Object Snap tab, to choose the running snaps. MellowCAD has no such dialog: type `-OSNAP` or `-OS` and a list of modes, or check them in the menu of the status bar's Object snap button.

### What is the shortcut key for object snap?

F3 turns object snapping on and off, as in AutoCAD; the status bar's Object snap button does the same. Shift + right-click at a point prompt opens the menu of one-point snaps.

### Why is object snap not working?

F3 may have turned it off: its status bar button shows it. Or the mode is not running: set it with `-OSNAP` or the button's menu. The cursor has to come within about 10 pixels of the point, and for a centre, over the circle or the arc itself. Snaps only work while a command asks for a point.

### How do I snap to a point just once?

At the point prompt, type the mode's capitals, such as `END` or `TAN`, or choose it from the Shift + right-click menu. It works for that point only, whether that mode runs or not.

### Do the object snap settings stay?

Until the page is reloaded; then they are Endpoint, Center, Intersection and Extension again. AutoCAD does not keep them in the drawing either.

## Related commands

- [SNAP in AutoCAD](https://mellowcad.com/docs/commands/snap.md)
- [FROM](https://mellowcad.com/docs/commands.md#from): Pick a point offset from a base point
- [LINE in AutoCAD](https://mellowcad.com/docs/commands/line.md)
- [ID in AutoCAD](https://mellowcad.com/docs/commands/id.md)