Filter Nodes

Filter nodes route points into Inside / Out (or Out) outputs based on spatial, numeric, or set-theoretic criteria. They never modify point data — only which output the point flows into.

All filter nodes are in the Filters category and share the dark-red node color.

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Difference

Description: Removes source points that overlap with the difference points' bounds. The spatial inverse of Intersection.

Ports

Name	Direction	Type	Notes
Source	Input	Point	Required. Points to subtract from.
Differences	Input	Point	Required. One or more point sets that define the subtracted region. Accepts multiple connections.
Out	Output	Point	Surviving source points.

Settings

Field	Type	Default	Description
densityMode	PPGDensityFunction	Binary	How density is recalculated after subtraction. Binary: a point is removed if any overlap exists, otherwise density is unchanged. Minimum: density is multiplied by (1 - maxOverlapRatio), allowing partial overlap to reduce rather than eliminate a point.
keepZeroDensityPoints	bool	false	When enabled, points that reach zero density (instead of being removed) are kept in the output with density = 0. Useful for downstream masking.

Notes

• Overlap is tested in world space using each point's AABB (boundsMin/boundsMax). Make sure bounds are set correctly before this node (see Bounds Modifier).
• When Differences is disconnected or empty, all source points pass through unchanged.
• Minimum mode is useful for soft feathering at the boundary; Binary is a clean hard cut.

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Filter by Attribute

Description: Filters points by comparing a named float metadata attribute against a numeric threshold. Points that pass the comparison go to Inside; the rest go to Outside.

Ports

Name	Direction	Type	Notes
In	Input	Point	Points to filter.
Inside	Output	Point	Points that pass the comparison.
Outside	Output	Point	Points that fail the comparison.

Settings

Field	Type	Default	Description
attributeSelector	PPGAttributeSelector	(none)	The metadata attribute (or built-in point property) to read and compare. Must resolve to a float value.
operation	CompareOp	GreaterOrEqual	Comparison operator: Equal, NotEqual, Greater, GreaterOrEqual, Less, LessOrEqual. Equality uses an epsilon of 1e-6.
threshold	float	0.5	The value the attribute is compared against.

Notes

• If attributeSelector is not set (invalid), every point is routed to Outside.
• Use this node together with Distance or Nearest Seed Assign to filter by computed attributes.
• You can leave Outside unconnected if you only need the passing set.

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Filter by Bounds

Description: Filters points within an axis-aligned bounding box (AABB) defined in local space. Points whose position lies inside the box go to Inside; the rest go to Outside.

Ports

Name	Direction	Type	Notes
In	Input	Point	Points to filter.
Inside	Output	Point	Points within the bounding box.
Outside	Output	Point	Points outside the bounding box.

Settings

Field	Type	Default	Description
boundsMin	Vector3	(-10, 0, -10)	Minimum corner of the filter box in local space.
boundsMax	Vector3	(10, 0, 10)	Maximum corner of the filter box in local space.

Notes

• When boundsMin.y == boundsMax.y (the default, both 0), the Y axis check is skipped — the filter becomes a 2D XZ-plane rectangle test. Set them to different values to enable Y-axis clamping.
• This node uses a Burst-compiled parallel job, making it efficient for large point sets.
• All positions are in the component's local space (before the component's own Transform is applied).

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Filter by Density

Description: Filters points whose density value falls within a [minDensity, maxDensity] range. Points in range go to Inside; others go to Outside.

Ports

Name	Direction	Type	Notes
In	Input	Point	Points to filter.
Inside	Output	Point	Points within the density range.
Outside	Output	Point	Points outside the density range.

Settings

Field	Type	Default	Description
minDensity	float [0..1]	0.5	Minimum density (inclusive) for a point to pass.
maxDensity	float [0..1]	1.0	Maximum density (inclusive) for a point to pass.

Notes

• Density is a normalized [0, 1] per-point float that represents relative importance or probability of placement.
• This node uses a Burst-compiled parallel job.
• A common pattern is to use Distance to write density, then this node to select a band by proximity.

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Filter by Index

Description: Routes points to Inside or Outside based on their sequential index in the input stream. Supports configurable start offset, count limit, and step (every Nth point).

Ports

Name	Direction	Type	Notes
In	Input	Point	Points to filter.
Inside	Output	Point	Points matching the index pattern.
Outside	Output	Point	Points not matching the pattern.

Settings

Field	Type	Default	Description
startIndex	int	0	First global index to include. Negative values are clamped to 0.
count	int	-1	Number of points to include. -1 means "all remaining from start".
step	int	1	Include every Nth point from the start. 1 = every point, 2 = every other point, etc. Values below 1 are clamped to 1.

Notes

• The index counter is global across all connected inputs, not per-input. If multiple point sets are connected, they are indexed continuously.
• Example: startIndex=0, count=10, step=2 keeps indices 0, 2, 4, 6, 8.
• Useful for selecting alternating rows, every Nth tree, or a specific head/tail slice of a set.

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Filter by Normal

Description: Filters points by comparing the point's up-vector (Y column of its transform) against a reference direction. Points within maxAngle degrees of the reference are sent to Inside; others to Outside.

Ports

Name	Direction	Type	Notes
In	Input	Point	Points to filter.
Inside	Output	Point	Points whose normal is within the angle limit.
Outside	Output	Point	Points whose normal exceeds the angle limit.

Settings

Field	Type	Default	Description
referenceDirection	Vector3	(0, 1, 0)	The direction to compare normals against. Automatically normalized at runtime.
maxAngle	float	30	Maximum allowed angle in degrees between the point's up-vector and the reference direction.

Notes

• The angle comparison is done using a dot-product threshold (cos(maxAngle)) instead of acos, which is more efficient.
• After Project to Surface, the point's up-vector stores the surface normal — use this node to separate flat and steep areas.
• This node uses a Burst-compiled parallel job.

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Filter by Spline

Description: Filters points based on whether they fall inside or outside a spline region on the XZ plane. For closed splines, uses a ray-casting point-in-polygon test. For open splines, uses a distance-to-curve test.

Ports

Name	Direction	Type	Notes
In	Input	Point	Points to filter.
Spline	Input	Spline	The spline that defines the filter region.
Inside	Output	Point	Points inside the spline region.
Outside	Output	Point	Points outside the spline region.

Settings

Field	Type	Default	Description
splineResolution	int	64	Number of samples used to approximate the spline as a polygon. Minimum clamped to 8 at runtime. Higher values improve accuracy at curved boundaries.
margin	float	0.0	Boundary margin in world units. Positive: expands the inside region (points near the outside of the boundary are included). Negative: shrinks the inside region (points near the inside of the boundary are excluded). For open splines, acts as the inclusion radius.
invert	bool	false	If true, the Inside and Outside results are swapped.

Notes

• The spline is sampled in world space and converted to the component's local XZ plane for testing. The Y axis is ignored.
• If the Spline input is disconnected or has fewer than 2 knots, a warning is logged and all points pass through to Inside.
• For open splines, a minimum effective radius of 0.5 is applied even when margin is 0.
• Uses UnityEngine.Splines (Splines package). The spline must be connected via a Spline data node.

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Intersection

Description: Keeps only source points that spatially overlap with the mask points' bounds. The spatial complement of Difference.

Ports

Name	Direction	Type	Notes
Source	Input	Point	Required. The point set to test.
Mask	Input	Point	Required. One or more point sets that define the keep region. Accepts multiple connections.
Out	Output	Point	Source points that overlap with the mask.

Settings

Field	Type	Default	Description
densityMode	PPGDensityFunction	Binary	How density is computed for kept points. Binary: density is unchanged for any point with overlap. Minimum: density is multiplied by the maximum overlap ratio, attenuating points that only partially overlap.

Notes

• If Mask is disconnected or empty, no points are output (the mask acts as a gate).
• Overlap is tested via world-space AABB intersection, so ensure bounds are set appropriately beforehand.
• Contrast with Difference: Difference removes overlapping points; Intersection keeps only overlapping points.

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Union

Description: Combines two point sets into one, preventing spatial duplicates. All points from A are kept. Points from B that do not overlap any point in A are also added.

Ports

Name	Direction	Type	Notes
A	Input	Point	Required. Primary point set; all points are always kept.
B	Input	Point	Required. Secondary point set; only non-overlapping points are added.
Out	Output	Point	Combined point set without spatial duplicates.

Settings

Field	Type	Default	Description
densityMode	PPGDensityFunction	Binary	How density is handled for B points near A. Binary: B points that overlap A are dropped entirely. Minimum: B point density is multiplied by (1 - maxOverlapRatio); both may survive with reduced density.
keepZeroDensityPoints	bool	false	When using Minimum mode, keeps B points that reach density = 0 instead of removing them. Only relevant in Minimum mode.

Notes

• If A is empty, all B points pass through unchanged (and vice versa).
• Output metadata is cloned from the first A input.
• This is a spatial union, not a simple concatenation — use Merge if you want to combine all points without overlap testing.
• B points that overlap multiple A points are judged against the single A point with the highest overlap ratio.