Frame Editor Reference

Virtual links

Virtual links connect nodes without adding stock material. They establish the oriented axes that other entities can follow.

Definition#

A Virtual link is an oriented, non-manufactured connection between two nodes. It establishes a logical axis and a dependency relationship, but it does not represent a tube, rod, profile, printable body, or bill-of-materials item.

Virtual links are the Frame Editor's principal construction geometry. Use one when another entity needs a span, direction, rotation reference, or link-relative position without requiring material along that span.

Terminals, direction, and length#

Every Virtual link has an ordered start node and end node. Their resolved positions determine:

  • the link's start position;
  • its direction from start to end;
  • its resolved length in millimetres;
  • a normal perpendicular to the direction.

Start and end order is therefore meaningful. Reversing the terminals reverses the link direction even though the same two points remain connected. Relative nodes and attachments can use that direction when interpreting offsets and orientation.

Length is derived from the terminal nodes and is read-only. Move either terminal—or change an upstream dependency that moves it—and the Virtual link resolves again.

Normal and rotation#

Direction alone cannot describe rotation around a link's own axis. The link's normal supplies that missing orientation.

The editor creates an initial normal automatically. Use Rotate link to rotate the normal clockwise or counter-clockwise without changing the terminals, direction, or length. In the scene, the offset green strip inside the translucent Virtual-link cylinder shows its current rotation.

The normal defines the zero-angle radial direction for Relative nodes and provides an orientation reference for link-hosted geometry. Rotating a link is therefore a design edit, not a camera operation.

What can depend on a Virtual link#

A Virtual link can support several kinds of downstream intent:

  • Relative nodes use it for axial placement and optional radial distance and angle.
  • Virtual-link attachments use it as a parent axis and orientation reference.
  • Physical links use Virtual links as their logical reference geometry.
  • Other Virtual links may depend indirectly on it through Relative terminal nodes.

When the link changes, the editor propagates the update through these relationships in the same reversible transaction. Recursive dependency paths are rejected.

A Virtual link says where a logical span is; a Physical link says that some or all of a logical span is manufactured from stock material.

Every Physical link is associated with a Virtual-link reference. Creating a Physical link may reuse an eligible existing Virtual link or create the reference needed for that member. The two entities remain distinct:

  • hiding the Virtual link does not delete or replace the Physical link;
  • the Virtual link remains available to Relative nodes and Virtual-link attachments;
  • the Physical link owns material and section properties that the Virtual link does not have.

Creating and editing Virtual links#

Create a Virtual link from the frame-level Add menu or from a selected node. Choose its start and end nodes, then verify the terminal order and orientation in the selected link card.

The main editing actions are:

  • rename the link;
  • change its start or end node;
  • rotate it around its axis;
  • hide or show it;
  • add a Virtual-link attachment from it;
  • delete it when its dependent construction is no longer needed.

Changing or deleting a reference link can affect dependent nodes, links, and attachments. The editor records the complete propagated result as one transaction so it can be inspected and undone.

Properties and relationships#

The main user-facing Virtual-link properties are:

  • Name: its human-readable identity.
  • Start node and end node: the ordered terminal pair.
  • Length: the resolved terminal-to-terminal distance.
  • Direction: the resolved start-to-end axis.
  • Normal or rotation: orientation around that axis.
  • Visibility: whether the construction link is shown in the scene.
  • On-link nodes: nodes that lie on and can anchor entities to this logical span.
  • Dependent nodes: Relative nodes whose position is defined by this link.
  • Hosted attachments: Virtual-link attachments positioned from it.

The editor does not allow a link to start and end at the same node, or two equivalent Virtual links to connect the same terminal pair.

Manufacturing and export#

A Virtual link contributes no stock member and no printable body by itself. It may still be essential to manufacturing because it positions downstream entities that do produce geometry.

For example, a short floor-to-frame Virtual link can orient a printable foot while remaining absent from the stock-member list. This preserves the design relationship without inventing a tube solely to carry the part.

Common mistakes#

  • Expecting a Virtual link to become material. Add a Physical link when the span should be manufactured.
  • Ignoring terminal order. Start and end determine direction, which affects placement and orientation downstream.
  • Rotating the camera instead of the link. Camera movement changes only the view; Rotate link changes the authored normal.
  • Using a helper link with no dependent purpose. Add construction geometry when another entity needs its axis or dependency, not merely to make the scene look structured.
  • Deleting a link to declutter the viewport. Hide it when the relationship should remain.

Watch the Triangle Frame narrated build to see Virtual links establish the logical triangle before any manufactured members exist.

Read Nodes for Absolute and Relative positioning, Physical links for manufactured members, or Virtual-link attachments for printable geometry hosted by a non-material axis.