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How-to

AutoCAD coordinates

How to type points in AutoCAD: absolute, relative and polar coordinates, a line of a given length at an angle, and polar tracking. Practise them free online.

Every point a command asks for can be picked on the drawing or typed. Typed, a point is two numbers, X and Y, separated by a comma, and where they are measured from depends on how you write them: from the origin, from the last point, or as a length and an angle from it. MellowCAD reads them as AutoCAD does with dynamic input on, its default. Each section draws one figure and shows its history.

Absolute coordinates

Measured from the origin, 0,0. The first point a command asks for is read this way: 20,10 is 20 along X and 10 along Y. After it, dynamic input reads a typed point from the last one, so a point measured from the origin takes # before it: #120,10.

A triangle, each corner measured from the origin.
  1. Command: LINE
  2. Specify first point: 20,10
  3. Specify next point or [Undo]: #120,10
  4. Specify next point or [Undo]: #70,80
  5. Specify next point or [Close/Undo]: C
A triangle, each corner measured from the origin.

Relative coordinates

Measured from the last point: how far to go along X, then along Y. After a command's first point, that is what a typed point means, and the history writes it with @ before it, as the command line reads it: 100,0 is 100 to the right of the last point, -50,70 50 back and 70 up. Typed with @ yourself, a point is relative wherever you type it.

The same triangle, each corner measured from the one before.
  1. Command: LINE
  2. Specify first point: 20,10
  3. Specify next point or [Undo]: @100,0
  4. Specify next point or [Undo]: @-50,70
  5. Specify next point or [Close/Undo]: C
The same triangle, each corner measured from the one before.

Polar coordinates

A length and an angle, measured from the last point: 100<0 goes 100 along X, 60<120 goes 60 at 120°. Angles are measured from the X axis, anticlockwise: 90° is up, 180° left and 270°, or -90°, down. The history writes them with @ too.

Three sides, each a length and an angle from the end of the last.
  1. Command: LINE
  2. Specify first point: 0,0
  3. Specify next point or [Undo]: @100<0
  4. Specify next point or [Undo]: @60<120
  5. Specify next point or [Close/Undo]: @40<210
  6. Specify next point or [Close/Undo]:
Three sides, each a length and an angle from the end of the last.

A line at an angle

To draw a line of a given length at a given angle, type the end as polar coordinates, 100<30. Or hold the angle first: type <30 and Enter, and the next point stays on that direction, on the cursor's side; then type the length, 100.

A line held to 30°, then given its length, 100.
  1. Command: LINE
  2. Specify first point: 0,0
  3. Specify next point or [Undo]: <30
  4. Angle Override: 30
  5. Specify next point or [Undo]: 100
  6. Specify next point or [Undo]:
A line held to 30°, then given its length, 100.

Polar tracking

With polar tracking on, F10 or its button on the status bar, the cursor shows a guide at every multiple of its angle, set from that button's menu, and a typed length goes along the guide. The tooltip says how far and at what angle the cursor is.

Polar tracking at 30°: its guide, and the distance and angle at the cursor.Polar: 60.00mm < 30°
  1. Command: LINE
  2. Specify first point: 0,0
Polar tracking at 30°: its guide, and the distance and angle at the cursor.

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