SA Landscape Patch

SA Landscape Patch makes the terrain conform to shapes built in the graph. Flatten a park lot so its ground meets the lot surface exactly, cut a walkway ribbon along a path, or press a level pad under a placed prop so it does not float or sink.

It is the one SA node that changes the world rather than only producing data. That makes two of its rules unusually important: the tracking hazard and Settle Props.

UE 5.8 only

This node ships in the UE 5.8 package and needs Epic's Landscape Patch plugin, which the package enables for you. It works in the editor only - during PIE, at runtime, and in a cooked build it passes its inputs through and changes nothing.

Pins

Pin	Type	Feed it
Areas	Spline, Polygon 2D	Closed shapes whose whole surface the terrain should meet - lots, plazas. SA Get Lots (filtered to park lots), SA Subdivide Lots, SA Polygon Merge, SA Polygon Offset, SA Get Network Boundary, or any Polygon 2D.
Paths	Curve	Lines the terrain should follow as a ribbon - walkways, trails, ring roads. Also accepts Polygon 2D and Landscape Splines.
Props	Point	Points with bounds. Each becomes a level pad at the prop's base, its footprint grown by Pad Expansion.
Patched Shapes	Point, Curve	Every input, passed through unchanged. Chain into surface creation, sampling, or spawning as usual.

All three inputs are optional - an unwired pin contributes nothing. Patched Shapes always forwards its inputs, whether or not the terrain was touched, so the rest of the graph never depends on the patch having run.

How each pin becomes a shape

• Areas use the closed outline. An open spline here is skipped with a warning - put it on Paths instead. A Polygon 2D's holes are filled, not carved; the node warns and names the hole count. For a band around a loop rather than a filled disc, use Paths.
• Paths become a ribbon of Path Width. An open spline makes a path with ends; a closed spline makes a loop path - a band following the loop with its middle left untouched. A Polygon 2D makes one loop path per ring, its outline and each hole. A Landscape Spline makes one path per landscape segment.
• Props use each point's bounds, flat at the bottom of the prop, grown outward by Pad Expansion.

Settings

Setting	What it does
Write Mode	Shape Surface moves terrain to each shape's own heights. Noise Only leaves the base terrain alone and adds just the Noise and Height Offset inside the shapes - a masked ground-roughening brush.
Apply Order	When several SA Landscape Patch nodes shape the same ground, higher paints later and wins where they overlap. Flatten a park at 0, carve paths into it at 1, press prop pads on top at 2. Stable across regenerations.
Blend	Set Height moves terrain in both directions. Raise Only never digs below existing terrain - good for parks on rolling ground. Lower Only never lifts it - good for sunken plazas. Not used in Noise Only mode.
Edge Fade	Width of the blend band outside each shape where surrounding terrain ramps to meet the edge. Inside the shape the terrain always matches exactly. 0 gives a hard vertical edge.
Fade Shape	Smooth eases both ends (most natural), Linear is a straight ramp, Ease Out keeps the boundary steep and flattens into the surroundings.
Height Offset	Raises or sinks the whole patched area relative to the shape's surface.
Landscape	Leave empty to use the landscape the shapes sit on. Set it explicitly when the level has several.
Texels Per Landscape Quad	Advanced. 1 matches the landscape's own resolution and is recommended - higher costs memory without adding detail the landscape can show, lower softens edges.

Paths: Path Width is the total ribbon width. Extend Path Ends extends open paths half a width past each end (a capped end); turn it off to cut flush where the path meets a road. Loop paths have no ends and ignore it.

Props: Pad Expansion is how far each pad extends beyond the prop's own footprint before the Edge Fade begins. Settle Props is advanced and explained below.

Noise: Noise Amount is how far the noise pushes terrain up and down (0 keeps it perfectly smooth). Noise Scale Meters is the feature size - small is choppy, large is long rolling undulation. Noise Edge Fade ramps noise up from zero at the boundary inward, so shape edges stay exact while the interior gets the full unevenness. Noise Texture replaces the built-in noise with a texture's red channel, where mid-gray means no change.

Each shape gets its own deterministic noise variation from its SA_LotSeed, so the same lot roughens the same way every regeneration.

Paint Layer: tick Paint Layer and name a layer to also paint it inside each shape, with the same Edge Fade. The layer must exist on the landscape's material and have a Layer Info assigned, or nothing is painted and the node warns.

Scope the selectors upstream

This node changes the landscape. PCG regenerates any component whose change-tracking keys match a changed actor - so if a world-reading node upstream is left at its default By Class, Actor, it tracks every actor in the level, the landscape included. This node then changes the landscape, which re-triggers the graph, which patches again, forever.

The SA street getters are already scoped to the Streets Network class. Any stock Get Actor Data or Get Spline Data feeding this node needs the same treatment: tag the source actors and select By Tag.

If the editor will not settle after adding this node, check the source getters' selectors before anything else.

Settle Props and regenerating forever

A prop projected onto the landscape - a Surface Sampler on the landscape, or a Projection node - lands on the very pad this node just wrote underneath it. Its Z moves, so the pad is rewritten, so the landscape changes, so the graph regenerates. With a Height Offset, noise, or a mesh whose pivot sits above its base, the ground drifts a little further on every lap.

Settle Props (on by default) stops that. Each pad keeps the ground height its prop had when it was first placed on that spot. Only height changes caused by this node's own patches are ignored:

• a prop that has moved sideways settles again at its new position;
• a prop whose ground changed for another reason settles again from that new height;
• a prop sitting in the echo of this node's own writes keeps its remembered height.

Turn it off only if a pad must follow every height change of its prop.

To forget every settled height and start over: Cleanup the PCG component, then Generate. There is no separate reset control.

For a log of which props anchored, moved, or were new on each run, set sa.LandscapePatch.SettleLog 1.

Convergence and cleanup

The patches are PCG-managed components on a spawned SA_PCG_LandscapePatches actor. A regeneration whose inputs did not change writes nothing at all, and Cleanup restores the unpatched landscape - so this node is safe to leave in a graph you regenerate constantly.

Upgrading a graph made before the Areas/Paths/Props pins

The earlier version of this node had a single Shapes pin. Spline connections migrate to Areas automatically. Point connections do not - re-drag them onto Props once, or the props will patch nothing.

Example: a park with a path through it

1. SA Get Lots into Filter Data By Attribute on SA_LotZone = Park, into Areas.
2. A drawn spline through the park, read with Get Spline Data scoped By Tag, into Paths. Set Path Width to the walkway width and turn Extend Path Ends off where it meets a road.
3. Get Actor Data, scoped By Tag to the placed benches and trees, into Props.
4. Set Blend to Raise Only so the park never digs into the surrounding hillside, Edge Fade to a few metres, and a small Noise Amount with Noise Edge Fade so the lot borders stay exact.
5. Chain Patched Shapes onward to build the park's surface and scatter on it.

For a second node carving something on top of this one, give it a higher Apply Order.