Object snaps and precision

Clicking "close enough" is not enough to draw accurately: object snaps take the cursor to exact points on objects (endpoints, centers, intersections...), and Ortho, polar tracking and object snap tracking guide it along exact directions. All these aids work only while a command is asking for a point.

Object snaps (F3)

With OSNAP on, moving the cursor near a key point shows a yellow marker with its name, and the click snaps to that point. F3 or the status bar button turns snaps on and off; right-clicking the button opens the list of modes, with Select All and Clear All. At startup all modes are on except Nearest.

Mode	Type	Point
Endpoint	END	End of lines, arcs, polyline segments
Midpoint	MID	Midpoint of a line, an arc or a segment
Center	CEN	Center of circles, arcs and ellipses
Node	NOD	Point objects
Quadrant	QUA	Points at 0°, 90°, 180° and 270° of circles, arcs and ellipses
Intersection	INT	Crossing of two objects
Extension	EXT	Extension of a line or arc beyond its endpoint
Insertion	INS	Insertion point of blocks, texts and attributes
Perpendicular	PER	Foot of the perpendicular from the last point
Tangent	TAN	Tangent point from the last point
Nearest	NEA	Point on the object nearest to the cursor

Snap override: when the command asks for a point, type the abbreviation (END, MID, TAN...) and press Enter: only that mode applies to the next point, even if OSNAP is off. The Spanish abbreviations (FIN, MED, CER...) and the underscore forms (_end) are accepted too. Object snaps also work inside inserted blocks and dimensions.

Object snap tracking (F11)

With OTRACK and object snaps on, rest the cursor on an object snap for half a second: the point is acquired and marked with a green cross. Horizontal and vertical tracking paths come out of each acquired point; the cursor snaps to them and to their intersections with other paths or with polar paths. Up to 7 points can be acquired; resting on one again releases it. The Extension mode is acquired the same way, by resting on an endpoint.

Ortho (F8) and polar tracking (F10)

ORTHO forces the next point to be horizontal or vertical from the last one.
POLAR snaps the cursor to directions that are multiples of the increment angle when it passes near them, with a dashed tracking path and a tooltip with the distance and angle. Right-click the button to choose the increment: 90°, 45°, 30°, 22.5°, 18°, 15°, 10° or 5°.

Ortho and polar tracking exclude each other: turning one on turns the other off. With either of them, typing just a distance places the point in the marked direction (see Coordinates and input).

Grid and snap (F9)

The model background shows a grid that adapts to the zoom: its spacing is a power of 10 with at least 25 pixels between lines. With SNAP (F9) the cursor jumps to the nodes of that grid. The grid cannot be configured or hidden yet (the GRID toggle and F7 are not available yet). With a rotated UCS, the grid, snap and Ortho follow its axes (see Coordinates and input).

Isometric drafting (F5, Ctrl+E)

To draw isometric views in 2D, turn on isometric drafting with ISODRAFT or the ISO button on the status bar. Ortho, the grid, snap and the crosshairs then follow the two axes of the current isometric plane:

Plane	Axes
Left	90° and 150°
Top	30° and 150°
Right	30° and 90°

F5 or Ctrl+E switch to the next plane (so does ISOPLANE), and ELLIPSE offers the Isocircle option to draw circles in the plane. The mode is saved in the drawing (SNAPSTYL and SNAPISOPAIR).

Order of priority

When several aids are on, the point is decided as follows: first the object snap under the cursor, if any; otherwise tracking (polar or object snap tracking); otherwise grid snap and Ortho. Dynamic input can then lock the distance or the angle with Tab.