Frame Editor Reference

Coordinate system and units

Frame geometry lives in one fixed, millimetre-based world coordinate system. Learn how its axes relate to local link coordinates, expressions, the floor grid, and the camera.

World coordinates#

Every resolved point in a frame has an X, Y, and Z world coordinate. The axes meet at the world origin (0, 0, 0) and do not change when you orbit, pan, or zoom the camera.

The Frame Editor uses a Y-up coordinate system:

  • X is the red axis.
  • Y is the green vertical axis.
  • Z is the blue axis.

The default floor grid is the XZ plane at Y = 0. It is a visual reference, not a solid floor, collision boundary, or automatic grounding constraint. Geometry may use negative coordinates or cross the grid unless the design relationships prevent it.

The positive-axis arrows at the origin are the authoritative orientation reference. Words such as “left”, “right”, “front”, and “rear” depend on the current camera view; X, Y, and Z do not.

Absolute and resolved positions#

An Absolute node owns three world-coordinate expressions directly. For example:

``text X = -150 Y = 20 Z = 0 ``

places the node 150 mm along negative X, 20 mm above the floor grid, and on the world Z origin.

A Relative node is authored in a Virtual link's local frame instead. It still resolves to one XYZ world position so the renderer, downstream links, attachments, and export can use it. Its authored relationship—not the displayed world-coordinate result—is what remains stable when the reference link changes.

Millimetres, ratios, and angles#

Frame geometry is authored in millimetres. Bare numeric values in coordinate, radius, thickness, length, and absolute-offset fields are interpreted as millimetres; enter 25, not 25 mm.

Some controls deliberately use other quantities:

  • a Relative-node position in Rel mode is a unitless ratio, where 0.5 means halfway along the reference span;
  • an attachment dimension in a relative mode is a multiplier of its documented parent dimension, such as Physical-link radius;
  • rotation and radial-angle controls are displayed in degrees.

Read the field label and its resolved-value readout together. A ratio may resolve to millimetres, while an authored millimetre expression may also be shown as a ratio of its current reference.

Frame export remains millimetre-scale. 3MF output declares millimetres explicitly; STL carries no unit metadata and should be imported into downstream software as millimetres.

Expressions and resolved values#

Many geometric fields accept either a literal or an expression using Frame reactive properties. The expression records design intent; the resolved number is the current result.

For example:

``text X = -baseWidth / 2 ``

might currently resolve to -150.000. Changing baseWidth then moves the node without replacing the expression with a fixed coordinate.

Resolved values shown in the interface may be rounded for readability. Dependencies and downstream geometry use the editor's resolved numeric value, not text copied from a rounded scene label.

The dedicated Reactive properties reference will cover expression syntax, dependencies, validation, and cycles in detail.

World frames and local frames#

World coordinates answer “where is this point in the frame?” A local frame answers “where is this point or part relative to its parent?”

An oriented link supplies:

  • a start-to-end direction;
  • a perpendicular normal that establishes rotation around that direction;
  • a local axial and radial reference for dependent nodes and attachments.

Relative nodes and link attachments are therefore usually authored with local distances, direction, and rotation even though the editor ultimately resolves their geometry into world coordinates.

Changing the camera changes neither frame. Rotating a Virtual link or attachment changes authored local orientation; orbiting the viewport changes only how that orientation is viewed.

Camera view versus model geometry#

Orbit, pan, and zoom are inspection operations. They do not:

  • change XYZ coordinates;
  • reverse link terminal order;
  • rotate a link normal;
  • move an attachment;
  • create a transaction in the frame history.

If an axis appears diagonal or points toward the screen after orbiting, use its color and positive arrow rather than the screen's horizontal and vertical directions. Select an entity and inspect its numeric fields when exact placement matters.

Common mistakes#

  • Treating the floor grid as a constraint. Y = 0 is only the default visual floor; nothing is grounded until the model expresses that relationship.
  • Reading screen direction as world direction. Camera orientation can make positive X appear leftward or make Y appear diagonal.
  • Adding unit suffixes to expressions. Geometric input fields interpret bare values in millimetres.
  • Confusing a ratio with a percentage literal. A relative value of 0.5 means 50%; entering 50 means a ratio fifty times the reference.
  • Replacing an expression with its current result. Doing so removes the reactive relationship even when the geometry initially stays in the same place.
  • Assuming scene-label precision is stored precision. Use the selected entity's authored expression and resolved-value field as the reference.

Read Positioning planes for placing and moving Absolute nodes, Nodes for the difference between world-authored and link-relative positions, or Virtual links for direction and normal.

Watch the Triangle Frame narrated build to see world coordinates and a positioning plane used in the editor before the logical links are added.