# PLINE in AutoCAD

> How AutoCAD's PLINE (PL) works, prompt by prompt: lines and arcs in one polyline, Width and Halfwidth, Length, Close and Undo. Try it free in your browser.

PLINE draws a polyline: one object made of straight segments and arcs joined end to end, each with a width. After the start point it says the current width; then each point adds a segment, until Enter or `Close` ends it. As in AutoCAD, it starts with lines: `Arc` switches to arcs, each tangent to the segment before it, and `Line` switches back. Enter at the start point continues from the end of the last line, arc or polyline drawn.

- **Command:** `PLINE`
- **Aliases:** `PL`
- **Panel:** [Draw](https://mellowcad.com/docs/commands.md#draw)
- **Try it:** [Open the editor](/draw), type `PL` 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.

A line, a tangent arc and a line back, then a head 10 wide tapering to 0: one polyline.

```text
Command: PLINE
Specify start point: 0,0
Current line-width is 0.00
Specify next point or [Arc/Halfwidth/Length/Undo/Width]: @70,0
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: A
Specify endpoint of arc (hold Ctrl to switch direction) or [Angle/CEnter/CLose/Direction/Halfwidth/Line/Radius/Second pt/Undo/Width]: @0,40
Specify endpoint of arc (hold Ctrl to switch direction) or [Angle/CEnter/CLose/Direction/Halfwidth/Line/Radius/Second pt/Undo/Width]: L
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: @-40,0
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: W
Specify starting width <0.00>: 10
Specify ending width <10.00>: 0
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: @-16,0
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]:
```

## Options

### `Arc` (`A`)

Arc mode: each endpoint draws an arc tangent to the last segment, or, as the first segment, leaving the way the last line, arc or polyline drawn ends. Hold Ctrl to switch its direction. The options below shape the next arc.

### `Close` (`C`)

Listed once there is a segment: closes the polyline back to its start and ends the command; in arc mode, with a tangent arc.

### `Halfwidth` (`H`)

As `Width`, but each width is measured from the centre of the segment to its edge.

### `Length` (`L`)

A line of the length you give, the way the polyline heads: along the last segment, or tangent to the last arc. A negative length goes back.

### `Undo` (`U`)

Takes back the last segment and goes on in the mode of the one before. With none left it says `All segments already undone.`

### `Width` (`W`)

The starting width, then the ending width, each typed or picked from the last vertex: 10 to 0 tapers to a point, as an arrowhead does. The ending width carries on to the next segments and, as PLINEWID, to the next PLINE.

### `Angle` (`A`)

Arc mode: the arc's included angle, then its endpoint, its centre or its radius.

### `CEnter` (`CE`)

Arc mode: the arc's centre, then its endpoint, its included angle or the length of its chord.

### `Direction` (`D`)

Arc mode: the direction the arc leaves the last vertex, in place of the tangent, then its endpoint.

### `Line` (`L`)

Arc mode: back to straight segments.

### `Radius` (`R`)

Arc mode: the arc's radius, then its endpoint or its included angle. A negative radius draws the major arc.

### `Second pt` (`S`)

Arc mode: a point the arc passes through, then its endpoint: an arc through three points.

## What it does not do yet

PLINEGEN: a new polyline lays its linetype segment by segment, as with PLINEGEN 0 (PEDIT's Ltype gen turns it on for one polyline). A dashed linetype on a wide segment is drawn solid. A wide segment's preview is not drawn in a dimmer shade, and the arc prompt is written on one line where AutoCAD breaks it in two.

[What it does and still lacks, in detail (in English)](https://github.com/ovelilla/mellowcad/blob/main/docs/coverage/draw.md#pline--pl--es-pol--pl--pt-br-plinha--pl)

## Questions

### What is the shortcut for PLINE in AutoCAD?

`PL`, then Enter or Space. The full name works too, and `_PLINE` in any language of AutoCAD.

### How do I draw a curved polyline?

Choose `Arc`: each point then ends an arc tangent to the segment before it, until `Line`. To smooth a polyline already drawn through its vertices, use `PEDIT` and its `Fit` or `Spline`.

### Why is my polyline drawn thick?

A width given in an earlier PLINE is kept, and the next polyline starts with it, as the line after its start point says. Choose `Width` and give 0 twice to draw thin again. With `FILL` off, wide polylines show as outlines.

### How do I join lines into a polyline?

Run `JOIN` and select lines, arcs and polylines that meet end to end: each chain becomes one polyline. Or run `PEDIT` on a line, answer `Yes` to turn it into a polyline, and add the rest with `Join`.

### How do I find the area or length of a polyline?

Run `AREA`, press Enter for `Object` and pick the polyline: a closed one reports its area and perimeter, an open one its length.

## Related commands

- [PEDIT](https://mellowcad.com/docs/commands.md#pedit): Edit Polyline
- [JOIN](https://mellowcad.com/docs/commands.md#join): Join
- [RECTANG](https://mellowcad.com/docs/commands.md#rectang): Rectangle
- [EXPLODE](https://mellowcad.com/docs/commands.md#explode): Explode