-OSNAP in AutoCAD

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
• Try it: Open the editor, 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.

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'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'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 and CIRCLE. The aperture and marker settings, APERTURE and AUTOSNAP.

What it does and still lacks, in detail (in English)

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
• FROM: Pick a point offset from a base point
• LINE in AutoCAD
• ID in AutoCAD