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ZSeam

Opens a seam (a cut) in a mesh or surface that is closed in one direction, like a tube or a cylinder. The seam goes where you choose, and the piece can then be flattened.

Toolbar button: ZSeam button

When to use

A tubular part cannot be flattened or unrolled because it is closed on itself. After ZSeam, the mesh or surface has a seam in the place you chose.

There are two seam types:

Seam type Use it to
ByPlane Cut a tube at a position you choose.
ByEdge Follow a path of edges that already exists in the mesh.

Before you start

ByPlane, mesh

  • It must be a single mesh (one connected piece), open at the ends: a tube with two open ends.
  • It can have holes.
  • It does not work on solid meshes (closed, with no open edges) or on meshes with several disconnected parts.

ByPlane, surface

  • A single surface, trimmed or not, closed in one direction (U or V).
  • It does not work on polysurfaces with several faces or on solids.

ByEdge, mesh

  • The mesh must be closed in one direction.

Steps

  1. Run ZSeam.
  2. At the Select seam type: prompt, choose ByPlane or ByEdge, by typing the letter or by clicking the option.

ByPlane, mesh

  1. When prompted Select a mesh or surface for the seam, select the object. The Copy option is available at this prompt.
  2. The open edges are shown as highlighted colored curves. When prompted Select the curve to position the seam, pick one of them.
  3. When prompted Select the seam position, move along the chosen curve. A semi-transparent red rectangle shows the area of the cut. Click to confirm.
  4. The seam is added to the mesh.

ByPlane, surface

  1. When prompted Select a mesh or surface for the seam, select the surface.
  2. When prompted Select the seam position, move over the surface. A red preview curve is shown. Click to confirm.
  3. The surface is now open at that position.

ByEdge, mesh

The active view changes automatically to Ghosted and goes back to its previous mode at the end.

  1. When prompted Select a mesh edge, pick an edge directly on the mesh. The Angle and Copy options are available.
  2. A temporary orange curve shows the path that was found.
  3. When prompted Select another mesh edge (Enter = apply Crease, Esc = cancel), you can pick another edge. Each new edge replaces the previous path. If you change Angle, the path is recalculated immediately.
  4. Press Enter to apply the seam along the path, or Esc to cancel. If no edge was picked, Enter just exits.

The path advances in both directions from the chosen edge, always choosing the straightest continuation. It also stops when it reaches the border of the mesh.

Options

Option Where it appears What it does Values Default
ByPlane Select seam type The seam is defined by a position: on one of the edges of the mesh, or on the surface. n/a Chosen with Enter
ByEdge Select seam type The seam follows a path of mesh edges, starting from the edge you pick. n/a n/a
Copy Object selection prompt (ByPlane) or edge prompt (ByEdge) No: the original is replaced by the result. Yes: the original is kept and the result is a new object. No / Yes No (back to No on every run)
Angle (ByEdge) Edge prompt Maximum angle between the two faces next to each edge for the path to continue through it. 0 to 180, in degrees 10

Result

  • ByPlane, mesh: the mesh has an opening (the seam) along the cut line.
  • ByEdge, mesh: the seam is applied along the path of edges.
  • ByPlane, surface: the surface is now open at the chosen position.
  • With Copy = No, the original object is replaced. With Copy = Yes, the original is kept and the result is a new object with the same attributes (layer, name, color).