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Reference

3DPOLY in AutoCAD

How AutoCAD's 3DPOLY (3P) works: a 3D polyline of straight segments, each point at its own Z, with Close and Undo, and how it differs from PLINE. Try it free.

3DPOLY draws a 3D polyline: straight segments through points that each have a Z of their own, as one object. Give the start point, then an endpoint for each segment, until Enter ends it; even a start point alone is kept, as a polyline of one vertex. Enter at the start point is refused with Invalid point.: there is no Continue option, which LINE has. A point typed with a Z keeps it, 30,0,15; one typed without, or clicked, lies at the elevation of the work plane, and a point snapped to an object takes the object's Z there. Points are read in the current UCS.

Unlike a PLINE it has no plane, no arcs, no widths and no thickness, and it is drawn continuous whatever its linetype, which it keeps. The whole polyline is one step that U takes back; Escape keeps what was drawn. PEDIT edits it with a shorter list of options, and its Spline curve fits a smooth curve to it.

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 3D polyline climbing 15 at each corner of a 60 by 40 rectangle on the ground, seen from the south-east.
  1. Command: 3DPOLY
  2. Specify start point of polyline: 0,0,0
  3. Specify endpoint of line or [Undo]: @60,0,15
  4. Specify endpoint of line or [Undo]: @0,40,15
  5. Specify endpoint of line or [Close/Undo]: @-60,0,15
  6. Specify endpoint of line or [Close/Undo]: @0,-40,15
  7. Specify endpoint of line or [Close/Undo]:
  8. Command: -VIEW
  9. Enter an option [Orthographic]: SEI
  10. Regenerating model.
  11. Command: ZOOM
  12. Specify corner of window, enter a scale factor (nX or nXP), or [All/Extents/Previous/Scale/Window/Object]: 0.8x
A 3D polyline climbing 15 at each corner of a 60 by 40 rectangle on the ground, seen from the south-east.

Options

Close (C)

From the second segment on: draws a segment back to the start point and ends.

Undo (U)

Takes back the last vertex, and goes on from the one before it. With no segment left: All segments already undone..

What it does not do yet

A curve-fitted 3D polyline reads None in the Properties palette's Fit/Smooth, which AutoCAD calls Quadratic or Cubic, and cannot be changed there. It cannot be a hatch boundary or ARRAYPATH's path, and the palette has no Material row. Dynamic input asks the start point in one box, its Z typed after a second comma, where AutoCAD shows X, Y and Z fields. The grips' hover menus, Stretch, Add Vertex, Remove Vertex and the rest.

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

Questions

What is the shortcut for 3DPOLY in AutoCAD?

3P, then Enter or Space. The full name works too, and _3DPOLY in any language of AutoCAD.

What is the difference between PLINE and 3DPOLY?

A PLINE lies in one plane and can have arcs and widths. A 3D polyline has only straight segments, but each vertex can be at a different height: a pipe run, a road's centre line, a cable.

How do I draw a 3D polyline at different heights?

Type each point with its Z, x,y,z, or snap to objects at the heights you want. Under dynamic input a point after the first is relative: 60,0,15 goes 60 along X and 15 up from the last one.

How do I make a 3D polyline smooth?

PEDIT it and choose its Spline curve: a smooth curve framed by the vertices. Decurve straightens it again.

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