Decals¶

Mesh decals are paint-like meshes that follow the surface below them: road markings, crosswalks, painted areas. They're shaped by splines and generate a thin mesh that fits the ground.

There are two kinds:

Mesh Decal Stroke: Lines painted along a spline, like lane markings.
Mesh Decal Area: A patterned fill inside a closed spline, like crosswalk stripes or a box junction grid, with optional outline lines.

A decal is split in two: the component says where the paint goes (its splines and how it lands on the surface), and a settings asset says what the paint looks like (its lines or fill, materials and thickness).

Creating a decal¶

Select the object with the spline you want to paint along, or inside.
Choose GameObject > World Toolkit > Decals > Mesh Decal Stroke or Mesh Decal Area. With a spline object selected, the decal is created as its child and already follows its first path.
Next to Settings in the decal's inspector, click New to save a new settings asset and assign it, or assign one you already have.
Click the arrow next to Settings to edit the asset right inside the decal's inspector.

Until it has a settings asset, a decal builds nothing and says Assign a settings asset to the decal.

Settings assets¶

The look of a decal is stored in an asset, shared by every decal that uses it:

Mesh Decal Stroke Settings (asset): The lines of a stroke. See Stroke lines.
Mesh Decal Area Settings (asset): The fill and outline of an area. See Areas.

Besides New in the decal's inspector, you can create them from Assets > Create > World Toolkit > Decals. Editing an asset rebuilds every decal that uses it, so one asset can drive all the lane lines of a scene.

Both kinds of asset also have:

Materials: The materials the lines and fills pick with their Material Index. They become the decal's renderer materials. An empty list, or an empty slot, uses the Material set under Create Options in the Modelling Create tab.
Thickness: Paint depth: extrudes the decal along the surface normal and closes its sides. Zero keeps it flat.

Changing a single decal

Edits made through a decal's inspector change the shared asset, and with it every decal that uses the asset. To change one decal only, give it its own asset first.

Splines¶

The decal component takes a list of Splines to follow or fill. A decal can use splines from different spline containers.

Samples Per Segment sets how closely the decal follows the spline between two knots. Raise it for tight curves.

For strokes, Spline Ranges limit which parts of each spline get painted. Leave the list empty to paint the whole spline. Each range picks a Spline from the decal's list and an Interval along it; enable Flip on a range to exclude that part instead.

Stroke lines¶

A Mesh Decal Stroke Settings asset holds a list of Lines, painted side by side along the spline. Each line has:

Setting	What it does
Name and Enabled	A label for the line, and a switch to leave it out without deleting it.
Lateral Offset	Sideways distance from the spline, in meters. Positive is to the right of the spline direction.
Width	Line width, in meters.
Width Segments	Quads across the line. Raise it for wide lines on uneven ground.
Trim Start / Trim End	Meters left unpainted at the start and end of the spline.
Dash	The dash pattern: Mode (Solid or Dashed), the Segments of the pattern (dash and gap lengths, repeated along the line), Phase to shift the pattern along the line, in meters, and Fit To Length to scale the pattern so the line starts and ends on a full dash.
Material Index and Color	Which of the asset's Materials to use, and a tint.
UV Tiles Per Meter	How many times the texture repeats per meter along the line.

Lines keep their full width around corners: at every knot the line turns with a mitered corner, so both of its edges stay the same distance apart.

Line Preset, below the stroke's inspector, sets up common markings in one click: pick Solid Line, Dashed Lane Line, Double Solid, Solid + Dashed or Dotted and click Apply. The preset replaces the lines of the stroke's settings asset, so every stroke sharing that asset changes too.

Areas¶

An area needs a closed spline. Its Mesh Decal Area Settings asset holds:

Fill Enabled: Paints the inside of the area. Turn it off to keep only the outline.
Fill: The pattern of the fill, see below.
Fill Lift: Extra height of the fill above the surface, on top of Surface Offset, for when the material's own depth bias isn't enough to keep it clear of the surface. 0.001 by default.
Outline: Lines painted along the border, with the same settings as stroke lines. Positive offsets move them outside the area.
Outline Lift: Extra height of the outline above the fill, so overlapping paint doesn't flicker. The outline sits at Fill Lift plus Outline Lift.

The fill's Kind sets its pattern:

Kind	Paints
Solid	The whole area.
Stripes	Parallel bands: crosswalk stripes, or diagonal hatching when angled.
Grid	Two crossing sets of bands, like a box junction grid.
Checker	Alternating squares.

Patterns have an Angle (around the world up axis, in degrees), an Offset (in meters, along the pattern) and a Band Width: the width of each band, or the size of the squares for Checker. Band Gap is the space between bands, for stripes and grids. Cross Band Width and Cross Band Gap set the crossing bands of a grid, which are only painted in the gaps between the main bands. The fill also has its own Material Index, Color and UV Tiles Per Meter.

The pattern is anchored to the position of the decal object: move the decal object, or change Offset, to slide the bands.

Junction box markings

Road junctions can paint a box marking from a Mesh Decal Area Settings asset: the junction keeps a child Junction Marking decal on its carriageway. See Junctions.

Fitting to the surface¶

The decal finds the ground by casting rays down from the spline. These settings are under Projection on the decal component, except Resolution:

Setting	What it does
Surface Layers	The collider layers the decal lands on.
Projection Height / Projection Depth	How far above and below the spline it looks for a surface.
Surface Offset	A small lift above the surface, to avoid flickering (z-fighting).
Offset Along Normal	Lifts along the surface direction instead of straight up.
Hit Backfaces	Also lands on the back side of faces.
Miss Behaviour	What to do where no surface is found: Keep Spline Height, or Remove Faces.
Resolution	The size of the triangles that follow the relief. Smaller values follow bumps more closely.

Rebuilding and status¶

Decals rebuild by themselves when you edit their splines, their component or their settings asset, and when you move the decal or its spline objects.

Note

Decals don't notice changes to the terrain or colliders below them. After editing the ground, click Rebuild in the decal's inspector.

The inspector shows the build status:

Status	Meaning
Ready. n faces.	The decal is built.
Ready. n of m points found no surface.	Built, but part of it found no surface below. See Miss Behaviour.
Assign a settings asset to the decal.	The decal has no settings asset.
Assign at least one spline to the decal.	The Splines list is empty.
The area needs a closed spline. or The area needs a spline enclosing some space.	An area's spline is open, or encloses nothing.
The spline has no length.	The spline, or the part of it left by the Spline Ranges, is empty.
The area outline crosses itself; part of the fill is missing.	Fix the spline so its outline doesn't cross itself.
No surface found below the decal. Check Surface Layers and the projection range.	No collider was hit at all.