OSNAP

OSNAP opens the Drafting Settings window. Its main job is choosing your object snaps. An object snap pulls the cursor onto an exact point of an object, such as the end of a line or the centre of a circle, so a click lands there exactly. The same window also holds the snap and grid, polar tracking and Dynamic Input settings.

How it works

Type OS and press Enter. The Drafting Settings window opens on the Object Snap tab. Tick the snaps you want, make sure Object Snap On (F3) is ticked, and click OK. Cancel closes the window without changing anything.

Command line

Command: OS
(tick Endpoint, Midpoint and Center on the Object Snap tab, then click OK)

DS, DSETTINGS, SE, DDRMODES, RM and DDOSNAP open the same window. After the first time, it opens on the tab you last used.

The snaps you tick are the running snaps: they work at every point prompt while object snap is on. Press F3, or click the OSNAP button on the status bar, to turn them all on or off. The menu on that button lists the snaps, so you can tick one without opening this window, and its Settings… opens this window.

The object snaps

When a running snap finds its point near the cursor, a marker shows there. Click and the point is used exactly.

Snap	Keyword	Finds	OSMODE
Endpoint	END	The ends of lines, arcs and elliptical arcs, and every corner of a polyline.	1
Midpoint	MID	The middle of a line, an arc or a polyline segment.	2
Center	CEN	The centre of a circle, an arc, an ellipse, or an arc segment of a polyline.	4
Node	NOD	A point object, as drawn by POINT.	8
Quadrant	QUA	The points at 0, 90, 180 and 270 degrees on a circle or arc, and the ends of an ellipse’s axes.	16
Intersection	INT	Where two objects cross.	32
Insertion	INS	The insertion point of a block, a text, a multiline text or an attribute definition.	64
Perpendicular	PER	The point on a line, circle or arc that makes a right angle with the last point you gave.	128
Tangent	TAN	The point where a line from the last point just touches a circle or arc.	256
Nearest	NEA	The point on an object closest to the cursor.	512
Geometric Center	GCEN	The centre of a closed polyline’s area.	1024
Apparent Intersection	APP	Where two lines, arcs or circles would cross if they went on.	2048
Extension	EXT	A point along a line or arc carried on past its end. Rest the cursor on the end first; a small cross marks it, and a dashed path shows the extension.	4096
Parallel	PAR	A point on the line through the last point that runs parallel to a line you hover over.	8192

The last column is the value each snap adds to the OSMODE system variable. Musa CAD starts with Endpoint, Center, Intersection and Extension on, which is OSMODE 4133.

A snap for one pick

At any prompt that asks for a point, type a snap’s keyword instead of the point. That snap alone is used for the next click, even if it is not a running snap and even with object snap off. The prompt shows the snap you chose.

Command line

Command: L
Specify first point: END
Specify first point: _end of (click near the end of a line)
Specify next point or [Undo]: PER
Specify next point or [Undo]: _per to (click on another line)
Specify next point or [Undo]: Enter

• You can give several at once, such as END,MID.
• NON means no snap at all for the next click.
• Longer spellings work too, such as ENDP, ENDPOINT or PERP.
• If nothing of that kind is under the cursor, Musa CAD says No Endpoint found for specified point. (with the snap’s name) and Invalid point., and asks for the point again.
• Hold Shift and right-click in the drawing for the same list as a menu. It also has Osnap Settings…, which opens this window.

The same menu and prompt also take four point helpers that are not snaps:

Type	What it does
FROM	Asks Base point:, then <Offset>:. The point is the offset, such as @20,0, from the base point.
M2P	Asks First point of mid: and Second point of mid:. The point is half way between them.
TT	Asks Specify temporary OTRACK point:. The cursor then tracks along the horizontal and vertical through that point.
TK	Asks First tracking point:, then Next point (Press ENTER to end tracking): for each move along one axis. Enter gives the point reached.

The Drafting Settings window

Object Snap tab

Part	What it does
Object Snap On (F3)	Turns the running snaps on or off.
Object Snap Tracking On (F11)	Turns object snap tracking on or off: rest the cursor on a snap point, then move away along the horizontal or vertical through it.
Object Snap modes	One check box for each snap in the table above.
Select All	Ticks every snap.
Clear All	Unticks every snap.

Snap and Grid tab

Part	What it does
Snap On (F9)	Turns grid snap on or off. The cursor then jumps in steps.
Snap X spacing:, Snap Y spacing:	The size of the steps. With Equal X and Y spacing ticked, Y follows X.
Polar distance:	The step along a polar tracking line, used with PolarSnap.
Grid snap, PolarSnap	Under Snap type: snap to the grid, or to steps along the polar tracking lines.
Grid On (F7)	Shows or hides the grid.
Grid X spacing:, Grid Y spacing:	The grid spacing. A spacing of 0 follows the zoom.
Major line every:	How many grid lines between the darker major lines.
Adaptive grid	Thins out the grid when you zoom out. Allow subdivision below grid spacing adds finer lines when you zoom in.
Display grid beyond Limits	Draws the grid outside the drawing LIMITS too.

Polar Tracking tab

Part	What it does
Polar Tracking On (F10)	Turns polar tracking on or off. The cursor then locks onto every step of the increment angle.
Increment angle:	The step between tracking angles. Pick 90, 45, 30, 22.5, 18, 15, 10 or 5, or type your own.
Additional angles:	Tick it and type extra angles, separated by commas, such as 12, 75.
Track orthogonally only, Track using all polar angle settings	Whether object snap tracking runs only horizontally and vertically, or along every polar angle.
Absolute, Relative to last segment	Whether polar angles are measured from the X axis or from the line you drew last.

Dynamic Input tab

Enable Dynamic Input (F12) turns on input at the cursor: the prompt, the coordinates, and the lengths and angles of what you are drawing. See Dynamic Input.

Good to know

• When several snap points are near the cursor, Musa CAD prefers them in this order: Endpoint, Midpoint, Center, Node, Quadrant, Intersection, Perpendicular, Tangent, Geometric Center, Insertion, Apparent Intersection, Parallel, Extension, Nearest. Turn off the snaps you do not need if the wrong point keeps winning.
• Hold Shift+A at a point prompt to turn object snap on or off for the moment. Hold Shift+E for Endpoint alone, Shift+V for Midpoint alone, or Shift+C for Center alone.
• Splines, dimensions, leaders, hatches, images and tables have no snap points of their own.
• The Dynamic Input tab only turns Dynamic Input on or off. Its other settings are system variables such as DYNMODE and DYNPROMPT.
• To set the running snaps by typing at the command line, use -OSNAP or OSMODE.

Compared with AutoCAD

Musa CAD starts with AutoCAD’s default running snaps: Endpoint, Center, Intersection and Extension. The one-pick keywords are AutoCAD’s, the prompt shows them the way AutoCAD does (_end of), and AutoCAD’s older spellings CENTROID and INSERT are taken too.

Next

• Learn every way to place exact points in Precision and drafting aids.
• Set the running snaps at the command line with -OSNAP.
• Draw with exact lengths and angles at the cursor with Dynamic Input.