Surface presets

What every preset field does, and the order to tune them in.

The shipped presets already carry these values. GP_Concrete, GP_Brick and the others in /GridDestruction/Presets/ are ready to use, so you do not type anything from this page to get a working wall. The value tables are folded away: open them when you make a preset of your own, want to compare materials, or need to get back to the shipped numbers after experimenting.

Three assets carry them, and the split matters:

asset	answers
GridSurfaceMaterialDataAsset (shipped: DA_GridSurfaceMaterials)	how this material fails: shared by every wall made of it
GridWallPreset (shipped: GP_*)	what this wall is: thickness, density, how much of it may go
GridCollapseVisualComponent on the wall	what its rubble does after it falls

Use one project-wide surface material asset and reference it from every preset. A surface type missing from its Configs map falls back to neutral values, so a partial map is valid.

Editing the numbers: GridMaterials.csv

Every number in tables 1 and 2 lives in one spreadsheet, Config/GridMaterials.csv in the plugin's folder: one column per preset, one row per field, and a Notes column saying what each does. The plugin's folder is Plugins/GridDestruction/ in your project, or Engine/Plugins/Marketplace/GridDestruction/ for a Fab install. Edit the CSV in Excel, Google Sheets or a text editor, then in the editor choose Tools → Execute Python Script and pick scripts/ue_apply_material_table.py from the same folder. The Python Editor Script Plugin must be enabled (it is by default).

It creates or updates each column's preset (row Asset) and its entry in the surface material asset (DA.* rows), then presses Apply Preset on every wall in the open level that uses one of them. Save the level afterwards. The log prints each field it changed as old -> new.

• An empty cell leaves that value alone.
• Point Asset at your own preset to tune it from the table; add a column for a second kind of brick. Two columns of one SurfaceType must agree on the DA.* rows, and the script stops if they do not.
• WallMesh and WallMaterial take asset paths. A preset the script created has neither, so fill them before a wall uses it.
• Masks, effects and CapEdges stay on the assets.
• The CSV wins. A value you changed by hand in the editor is overwritten on the next run unless its cell is empty.
• It reaches only walls in the open level whose preset is a column. In another level using the same presets, run it there too or press Apply Preset; a wall that missed it logs GRIDSTAMP at BeginPlay.

Work on copies

Copy the shipped GP_* presets and the surface material asset into your project, and point the CSV's Asset and SurfaceMaterialData rows at the copies. A plugin update then never overwrites your tuning.

Table 1: the surface material asset

DA_GridSurfaceMaterials → Configs → one row per surface type.

Shipped values: open the table

	Concrete	Brick	Stone	Wood	Metal	Glass
DamageResistance	1.0	0.9	1.4	0.6	2.0	0.3
FalloffScaleU	1.0	1.6	0.9	3.0	0.8	1.2
FalloffScaleV	1.0	0.7	0.9	1.0	0.8	1.2
SmoothingAngleDeg	30	25	20	35	60	15
RicochetAngleDeg	15	15	18	10	30	0
GrazingDamageScale	0.35	0.35	0.30	0.50	0.10	1.0
EdgeProfile.Style	Rounded	Square	Rounded	Shard	Rounded	Shard
EdgeProfile.AmplitudeU	0.30	0.30	0.25	0.30	0.08	0.35
EdgeProfile.AmplitudeV	0.30	0.04	0.25	0.06	0.08	0.35
EdgeProfile.QuantiseU	0	0.15	0	0	0	0
EdgeProfile.QuantiseV	0	0	0	0	0	0
EdgeProfile.DepthNoise	0.25	0.15	0.30	0.20	0.05	0.10
bBrittle	false	false	false	false	false	true
BrittleBreakFraction	0.35	0.35	0.35	0.35	0.35	0.35
BrittleShardSizeCm	12	12	12	12	12	12

Why each column looks the way it does

• Concrete is the reference: resistance 1.0, chaotic spall on both axes, a circular blast. Every other column is a departure from it.
• Brick fails along its courses. QuantiseU 0.15 against AmplitudeU 0.30 gives discrete levels that read as mortar joints rather than noise, and AmplitudeV 0.04 keeps the courses straight. FalloffScaleU 1.6 against 0.7 spreads a hit sideways along a course instead of down through one.
• Stone is the hardest masonry: high resistance, the highest DepthNoise so the crater surface is rough, and a low smoothing angle so chips stay faceted.
• Wood splits along the grain: FalloffScaleU 3.0 against 1.0 makes a hit reach three times as far along the grain as across it. U and V are the visible texture's axes, so rotating Wall | UV by 90° for upright boards turns the grain with them.
• Metal deforms rather than breaks: the highest resistance, the smallest edge amplitude and a 60° smoothing angle, so it reads as bent sheet.
• Glass shatters: the lowest resistance, the largest amplitude and a hard 15° smoothing angle.

The fields

DamageResistance

How much of each bite this material takes. It changes how many shots a wall takes and almost nothing about how it looks. Thickness is the real durability knob; resistance saturates once a blast is deep enough to open a cell.

FalloffScaleU / FalloffScaleV

The blast's shape along and across the texture. The single most recognisable knob, and it costs nothing.

SmoothingAngleDeg

Normals are smoothed across folds flatter than this. -1 means unset (the wall mesh component's own value), 0 is flat shading. An angle above atan(halfThickness / cellSize) never engages: at 10 cm cells and 15 cm thickness that limit is 37°.

RicochetAngleDeg / GrazingDamageScale

What a shallow hit takes off. The angle is measured off the surface: 90 is straight on, 0 is along the wall. Below it the bite ramps down to GrazingDamageScale at 0°. A ricochet angle of 0 means the material never grazes. Keep GrazingDamageScale above 0 for anything that spalls: a skipping round still ploughs a furrow, and a shot that leaves no mark reads as a broken wall. The plugin decides how much material came off; whether the projectile deflects, sparks or stops is your weapon's call, using Obliquity and bGrazing in the damage result.

EdgeProfile.Style

How a hole's outline is drawn. Square follows the cells' sides, honest for brick. Shard cuts outward corners on the diagonal, so a staircase becomes a straight cut. Rounded relaxes the contour so stairs become straight runs and corners round off. Render only: the collider stays on the cells.

EdgeProfile.AmplitudeU/V, QuantiseU/V, DepthNoise

The rim's jitter in the wall's plane, its banding, and the roughness of the crater's floor. Amplitude above 0.40 is refused: two neighbouring vertices would swap places. Keep Quantise around half the amplitude; at twice the amplitude or more every vertex rounds to zero and the axis has no jitter at all. Apply Preset warns about both.

bBrittle, BrittleBreakFraction, BrittleShardSizeCm

A brittle cell is whole or gone, so a pane never shows a dish or a dent. BrittleBreakFraction is the share of a cell's thickness one hit must take to break it for certain; smaller hits break it with a proportional chance, so a blast's edge cracks unevenly and repeated hits always get through. Lower it for thin panes, raise it for laminated glass. The pane is divided into irregular shards about BrittleShardSizeCm across, and a hit breaks out whole shards connected to the impact. The roll is made on the server, so every machine sees the same holes.

Two kinds of brick

SurfaceType has six values and no Custom. That is deliberate: the enum is a lookup key for "what is this physically", for effects and sounds. Everything that differs between a red brick and a grey one lives on the preset.

You want	Do this
Two brick walls that break differently	Two presets, both SurfaceType = Brick
...that also resist differently	Point their SurfaceMaterialData at two different data assets
Glass that shatters vs glass that spiders	Two presets, different FractureWeightMask

Table 2: the wall preset

Shipped values: open the table

	Concrete	Brick	Stone	Wood	Metal	Glass
ThicknessCm	25	20	40	8	4	2
CellDensity	4	4	3	5	5	6
SubdivisionFactor	2	4	2	2	1	1
StructuralThreshold	0.25	0.30	0.20	0.40	0.15	0.60
MaxOverhangCm	200	150	120	150	300	60
MaxDestructionPercent	1.0	1.0	1.0	1.0	1.0	1.0
MinSpallRadiusCells	1.5	1.4	1.2	1.6	0.8	1.5
ExitSpallDepthScale	0.35	0.40	0.30	0.45	0.15	0.40
ExitSpallRadiusScale	1.6	1.7	1.5	1.8	1.2	1.2
ObliquityStretch	1.0	1.2	0.8	1.2	0.6	0.4
ObliquitySkew	1.0	1.2	0.8	1.2	0.6	0.4
BreachFalloffCells	3.0	2.5	3.5	2.5	1.5	4.0
FractureNoise	0.40	0.30	0.45	0.30	0.10	0.20
FractureNoiseScaleCm	20	20	25	10	15	15
FractureMaskContrast	2.0	2.0	2.0	2.0	2.0	2.0
bDeriveFractureMaskFromMaterial	true	true	true	true	false	false
SpikeSuppressionChance	0.7	0.7	0.7	0.7	0.7	0.7
MinSupportingNeighbours	2	2	2	2	2	2
HoleRimThicknessFraction	0.10	0.12	0.10	0.18	0.30	0.45
EdgeCrumbleScale	1.0	1.0	1.0	0.8	0.25	0.9
RevealCrushScale	1.5	1.8	1.3	2.0	1.0	2.5
CornerChipScale	4	4	4	4	0	0
EdgeFirst	1	1	1	1	0	0
DentStepCm	3	4	4	2	0	0
CapEdges	per placement

Size and structure

ThicknessCm, CellDensity

How deep the wall is, and cells per metre. Bigger cells hold more depth, so a wall that opens with no dent first wants a lower density or more thickness.

SubdivisionFactor

A cell splits into factor × factor fine children on its first bite. Detail, and its cost on the wire, exist only where the wall was hit. Raise it when a MASKSCALE line asks for it, or when an edge on show looks too smooth.

StructuralThreshold

The remaining fraction below which a cell stops carrying load. Wood gives up its load path long before it opens; reinforced concrete carries down to a shell; glass sheds whole panes at the first serious crack.

MaxDestructionPercent

The share of the wall that shooting may remove: 0 for a level boundary, 0.3 for a load-bearing element. Per wall, not per material, which is why the row is uniform. It gates shooting only: a severed piece still falls, and a collapse counts against the cap.

MaxOverhangCm and BuiltOverhangs

A cell is held only if it is within MaxOverhangCm sideways of a column that stands on, or hangs from, a support. Up and down are free on an upright wall, so an intact wall always stands; a cantilever longer than the limit loses its tip, and a beam held at both ends spans twice the limit. On a ceiling or floor neither axis is free.

• Keep it above half the widest opening with no wall under it, or the lintel over it falls on the first hit anywhere on the wall.
• 0 turns it off. The limit is rounded down to whole cells.

What was built stands: the limit counts from how far a wall reached when damage first came to it, so it drops only what damage leaves overhanging. A wall built past the limit logs an OVERHANG line once. BuiltOverhangs on the preset (Wall | Durability, advanced) picks a stricter rule:

value	a span built past the limit
Keep (default)	stands; the limit judges only what damage leaves
SettleSilently	is gone when the level starts, with no debris or sound
Collapse	comes down when the level starts, with debris and falling pieces

Shape of a hit

MinSpallRadiusCells

The crater of a hit that brings no radius of its own (RadiusCm = 0). A weapon that passes a radius keeps it on a wall that subdivides, so a small round can leave a small mark without a denser grid; at SubdivisionFactor 1 this is the floor under every hit. If an edge looks too smooth, lower it to 0.8–1.0 on brick and concrete for a more local bite, and raise FractureNoise to keep small holes from reading as squares. Do not take it to 0.

ExitSpallDepthScale, ExitSpallRadiusScale

The blowout of the far face, as a fraction of the wall's thickness and a multiple of the hit's radius. It starts once the deepest cell in a hit is eaten past ThroughCouplingThreshold of the thickness (0.8 by default, on the wall's GridData component). Brittle materials throw more off the back; metal petals instead. 0 switches it off for the material.

ObliquityStretch, ObliquitySkew

A glancing hit becomes a furrow instead of a dish. The stretch lengthens the crater along the shot's direction; the skew slides it forward. Keep the two equal: that pins the trailing edge where a square-on crater's would be and sends all the added length forward. Below it the crater grows backwards, above it the crater leaves the impact point.

FractureNoise, FractureNoiseScaleCm

Varies each cell's resistance by a fixed amount, so a small hole does not read as a square. Above about 0.6 the rim turns noisy and specks survive inside holes. Clamped at 0.9.

FractureMaskContrast, bDeriveFractureMaskFromMaterial

Strength of the break pattern, and whether it comes from the wall material's height map. See Setup → Where the wall breaks.

SpikeSuppressionChance, MinSupportingNeighbours

Clean slivers off a hole's rim. A cell with fewer standing neighbours than the minimum is pruned with this chance. The chance is 0.7 on purpose: a rim with every spike pruned reads as machined. Keep the minimum at 2: higher strips the rim of every hole. By default the chance follows the break pattern, so brick cleans up along its joints and keeps its teeth on the bricks. SpikeSuppressionMask paints it per wall; SpikeMaskStrength sets how far a mask moves it.

Edges and rims

HoleRimThicknessFraction

The band of wall left standing at a hole's edge, as a fraction of the thickness: what makes a hole read as a break in a solid rather than a cut in paper. Thin materials need more to show anything. It is also depth the crater cannot reach, so too much flattens craters; above about 0.5 a hole reads as a bevelled port.

EdgeCrumbleScale

How much an exposed edge (a capped side, a reveal) wanders as it erodes: crisp when intact, the material's own jitter when eaten. It needs a real EdgeProfile amplitude to show.

RevealCrushScale

A shot into a side (a reveal, a capped end, the bore of a hole) cuts that side along its own normal by PeakDepthCm × RevealCrushScale. 0 makes such a shot an ordinary face hit.

CornerChipScale

A shot at the face near an edge also chips the edge. Values near 1 make an edge give way about as fast as a shot straight into it; the shipped 4 makes corners crumble visibly faster than the face. Lower it toward 1–1.5 for a sturdier look. 0 switches it off.

EdgeFirst

In a cell at an edge, a face hit dents the face by 1 − EdgeFirst of its bite. At 1 the corner crumbles away before the face behind it gives. Does nothing while CornerChipScale is 0.

DentStepCm

Dents are drawn in whole steps of this depth, so a hit drops a chip instead of crumpling the face. A hit shallower than one step leaves the geometry flat and is shown by the damage material. The collider uses the same steps. 0 draws the exact depth.

BreachFalloffCells

Purely visual: how far, in cells, the "near a hole" channel of the damage material reaches. Glass at 4.0 is the deliberate outlier: its cracks radiate far past what was removed.

CapEdges: closing the wall's own sides

Per placement, not per material. A wall's outer perimeter is open by default, because most walls are seated in a frame or a facade. Tick the sides a player can see:

the wall is	tick
seated in a frame, or flush between two others	nothing
protruding from another wall at 90°	the exposed end only
a free-standing barricade or a pillar of wall	all four
a panel whose top the player can see over	Top

A cap breaks with the wall: it is built from the same cells as a hole's rim. If a capped edge looks like a knife edge, raise HoleRimThicknessFraction.

Table 3: rubble

On the wall's GridCollapseVisual component, not on the preset.

Shipped values: open the table

	Concrete	Brick	Stone	Wood	Metal	Glass
DebrisMassScale	1.0	0.9	1.3	0.35	0.8	0.5
ChunkLifetimeSeconds	1.6	1.6	2.0	1.4	1.4	1.0
KeepSettledAboveSizeCm	0	0	0	0	0	0

• Mass comes from the physical material first. Set PhysicalSurface on the preset; DebrisMassScale is taste on top. Leave it at 1.0 until the physical materials are in place.
• Keep KeepSettledAboveSizeCm at 0 in multiplayer (it is read as 0 in any networked game). Rubble never replicates, so a piece left standing would be cover in a different place on every client that nothing can remove.

knob	default	raise it when	lower it when
SettleLinearVelocityThresholdCmS	2.0	rubble twitches instead of resting	a chunk freezes in the air
SettleHoldSeconds	0.5	a chunk freezes in the air	settled rubble simulates longer than needed
EjectImpulse	400	chunks fall back into the hole they made	chunks fly like litter
TumbleDegreesPerSecond	45	rubble reads as rigid	rubble spins like a prop

The first two are clamped to a safe range when read. A wall carrying an out-of-range value says so once at BeginPlay in a HANGRISK line.

Where each knob lives

knob	lives on	survives Apply Preset?
table 1	the surface material asset → Configs[SurfaceType]	read live
table 2	GridWallPreset	stamped, so the preset wins
bAutoLinkSeams, SeamToleranceCm	GridWallPreset	stamped
AnchorEdges	the placed wall's GridData, Grid | Anchors	not stamped: edit it on the wall
ThroughCouplingThreshold, ThroughCouplingScale	the placed wall's GridData, Grid | Config	not stamped: edit them on the wall
bEmitDamageAttributes	the placed wall's GridWallMesh, Grid | Visual	not stamped: edit it on the wall
table 3	the placed wall's GridCollapseVisual	not stamped

Checking that a wall runs what the preset says

GridDestruction.CheckPresets

GRIDSTAMP [BP_Wall_Brick_7]: MATCH against preset 'GP_Brick' — ...
GRIDSTAMP [BP_Wall_Brick_9]: STALE against preset 'GP_Brick' — 1 field(s) differ:
    MinSupportingNeighbours live=2 preset=3. ...
GRIDSTAMP SUMMARY: 11 wall(s) — 1 stale, 0 without a preset, 10 current.

STALE means your edit never reached that wall: press Apply Preset on it and save the level. MATCH means the wall really runs the asset's values, so a knob that still looks inert is not a stamping problem. The same check runs on its own at BeginPlay on the server, and Log Preset Stamp Drift beside Apply Preset checks one wall. It reports and never corrects: a value set on the component alone is a legitimate per-wall override.

A Blueprint's own Class Defaults override the C++ defaults. If a knob does nothing, look at the placed actor's Details panel before anywhere else.

Tuning order

The tables are meant to be right on the first build. When a wall does not look like its material, work in this order, because each step changes what the next one is looking at. Change one number at a time.

1. Silhouette: does the hole have the right shape?

Look at one hole from the front.

what you see	do
the hole is a square	raise FractureNoise, or give it a break pattern
the rim is noisy rather than rough	lower FractureNoise below 0.6
specks of wall survive inside the hole	lower FractureNoise, or raise SpikeSuppressionChance
the rim has no teeth	raise EdgeProfile.AmplitudeU/V, or lower SpikeSuppressionChance
brick cracks through the bricks, not the joints	give it the material's height map, or raise FractureMaskContrast

2. Thickness: does the hole read as a break in a solid?

Look at the same hole from an angle.

what you see	do
the edge is a knife edge	raise HoleRimThicknessFraction
a visible band, but the crater looks shallow	lower it
the wall's own outer edge is open	tick the right CapEdges
a shot at a doorway's reveal dents the face	raise RevealCrushScale
a shot at the face next to an edge never chips it	raise CornerChipScale
the rim looks like the face, not like broken material	use the damage material

3. Depth: does a hit dent before it opens?

Shoot the same spot repeatedly.

what you see	do
the wall opens with no dent first	lower CellDensity, or raise ThicknessCm
the crater is a flat disc	raise EdgeProfile.DepthNoise
the crater bottoms out early	lower HoleRimThicknessFraction
the far face stays flat until it opens	lower ThroughCouplingThreshold on the wall, or raise ExitSpallDepthScale
holes are crisp but cost too much	lower SubdivisionFactor; see Multiplayer

4. Identity: is it the right material?

The three knobs that carry most of a material's identity, in order: FalloffScaleU/V, SmoothingAngleDeg, EdgeProfile.QuantiseU. DamageResistance comes last: it changes how many shots a wall takes, not how it looks.

Then fire along the wall:

what you see	do
a glancing hit leaves the same disc as a square one	ObliquityStretch is 0: type table 2's row
the furrow reaches behind where the round touched	raise ObliquitySkew to equal ObliquityStretch
the crater has left the impact point	lower ObliquitySkew below ObliquityStretch
a glancing hit on steel digs as deep as a square one	RicochetAngleDeg is 0: type table 1's row

5. Weight: does the rubble belong to the wall?

Author PhysicalSurface physical materials before touching DebrisMassScale.

6. The overlay: does the damage read as damage?

See Damage material.