Snaplines - Smart UI Guides & Grids

Snaplines brings the ruler-and-guide workflow you know from Photoshop, Figma, or Sketch straight into the Unity Scene View — built specifically for Canvas-based UI.

Drag guides from the ruler edge, position them by pixel value, lock them in place, label and color-code them by group. Every guide persists per-canvas, per-scene, so you never lose your layout marks between sessions.

The snapping system goes well beyond simple grid snap. Enable it and your RectTransforms will snap to guides, canvas edges, canvas midpoints, sibling object bounds, and sibling midpoints — all at once if you want. Visual indicators show exactly what you snapped to: a color-coded line, a diamond marker on the ruler, and a pill label with the coordinate and target type. Works during both move and resize operations, and every snapped move is fully undoable.

A configurable grid overlay with adjustable size, subdivisions, and five origin modes (Center, TopLeft, TopRight, BottomLeft, BottomRight) sits on top of the canvas. Subdivision lines double as additional snap targets when grid snapping is on.

The floating toolbar overlay appears automatically when you select a Canvas and collapses back when you leave it. All toggles — rulers, guides, grid, cursor readout, snapping targets — are one click away. The Guide Manager window gives you a sortable list of every guide on the active canvas with inline editing for position, label, and lock state.

Everything is editor-only. No MonoBehaviours, no ScriptableObjects, no files added to your project. Settings live in EditorPrefs and survive domain reloads, play-mode transitions, and Unity restarts. The snapping hot path allocates zero heap memory per frame.

Requires Unity 6 (6000.0+). Works with all three Canvas render modes — Screen Space Overlay, Screen Space Camera, and World Space.