Lofting Attribute (Pro)

Note

Inherited from Generate Attributes — shares its anchor, alignment, and per-key transform channels.

Lofting sweeps one or more 2D cross-section profiles along the lane to build a continuous surface — the tool for bridges, tunnels, retaining walls, and multilevel interchange decks. Unlike the other Generate Attributes (which repeat a mesh/component), lofting extrudes a shape, so the result is a single watertight run that follows the road’s curvature, width, and the per-key transform channels (Scale, Offset, Roll, width overrides, …).

You draw a 2D cross-section in the road’s R–H plane; the attribute sweeps it along the lane (S) — following the road’s curve and width — into one continuous surface.

Add it and place keys with Attribute Mode. A Lofting profile is a Blueprint subclass of the Lofting descriptor; create several subclasses for different shapes, and add multiple lofting attributes to the same lane to build independent lofted meshes (e.g. a deck plus its parapets).

Size control

How large the lofted mesh is across its cross-section depends on each item’s Coordinate System:

• Relative (Normalized) (default) — you draw the cross-section curve in a normalized −1 … +1 box that MetaRoad stretches onto the lane at bake, so the loft adapts to the road: X = −1 lands on the lane’s left edge and X = +1 on its right edge (exactly as wide as the lane, following its width changes), and Y = 1.0 equals half the lane width, so the loft keeps its proportions as the road widens or narrows. The anchor position, Alignment, Alpha, and Override Left/Right Width behave exactly as for every other Generate Attribute.

• Absolute (cm) — the curve’s X and Y are literal centimeters (X = offset from the reference line, Y = height above the surface), so the loft keeps a fixed real-world size regardless of lane width (alignment and width overrides are ignored).

To give the loft a fixed height instead of scaling it with the lane, enable bOverrideHeight:

Field	Default	Description
bOverrideHeight	off	Fix the lofted height instead of scaling it with the lane width
OverrideHeight	500 cm	With bOverrideHeight on, the world height that the profile’s Y = 1.0 maps to (blended between keys)

Create new Attribute

Create a new attribute from the Content Browser under the Meta Road category:

In the Pick Parent Class dialog choose RoadLaneAttributeLoftingDescriptor:

Lofting Attribute editor

Double-click a Lofting profile to open its dedicated 2D cross-section canvas — you draw the profile once and it is extruded along the road.

• Canvas viewport — the 2D cross-section, drawn in the road’s R (horizontal) / H (vertical) plane. All cross-section items are shown together; the active item is highlighted.

• Details panel — the descriptor: its value template and the list of cross-section items.

• Selected Item panel — the properties of the item you are currently editing.

Canvas controls: LMB drag moves a point or its tangent handle; RMB opens a context menu to add/delete points and items; Scroll zooms; MMB / RMB drag pans.

Cross-section items

The profile is built from one or more cross-section items — each is a 2D curve plus a material. An open curve becomes an extruded shell (a deck, wall, or barrier); a closed curve becomes a tube (a rail or pipe). Add several items, each with its own material, to build a compound profile — for example a deck, its parapets, and a curb in a single Lofting attribute.

Item property	Default	Description
Curve	—	The 2D cross-section shape (a 2D spline). Open curve → an extruded shell; closed curve → a tube
CoordinateSystem	Relative	Relative (Normalized) — X/Y in −1…1, mapped onto the lane (see Size control). Absolute (cm) — X/Y are centimeters from the reference line / surface
Material	—	Material applied to this item’s mesh strip
ChordTolerance	2	Curve → polyline tolerance [cm]; smaller = smoother
UVScale	(1, 1)	UV tiling — X across the cross-section perimeter, Y along the road path
bFlipNormals	off	Reverse triangle winding (flip faces inward)
bGenerateCaps	on	For closed curves only — triangulate end caps at each lofted segment

Drag and Drop

Drag a Lofting attribute profile from the Content Browser onto a road lane to add it directly:

Examples

MetaRoad ships ready-made Lofting profiles in /MetaRoad/MetaRoad/Profiles/Lofting. Apply one directly, or open it in the editor to see how its cross-section is assembled and use it as a starting point:

• TunnelSample1 — a tunnel.

• BridgeSample1, BridgeSample2 — bridge decks.

See also

• Generate Attributes — the base family Lofting belongs to (shared anchor / alignment / per-key transform channels).

• Attribute Profile — how attribute assets are created in the Content Browser.

• Attribute Mode — add the attribute and place keys along a lane.