Houdini 19.0 Nodes Geometry nodes Partition

Partition geometry node

Places points and primitives into groups based on a user-supplied rule.

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Note

This SOP creates a large number of disjoint groups. This is often a very inefficient workflow. Instead, consider creating a single string attribute that stores what would be your group name using Attribute Create or Attribute Wrangle. If the string attribute you make was named tag, you can isolate all the elements named kiwi with the ad-hoc group @tag=kiwi

To convert a set of disjoint groups, such as created by this SOP, into a single string attribute use the Name from Group option of the Name SOP.

The Partition SOP places points and primitives into groups based on a user-supplied rule. For example, in order to put each point in its own group named pt_pointnumber, enter the rule pt_$PT.

The rule can be any valid Houdini expression. Rules should evaluate to valid group names. The result of a rule may be modified to make it a valid group name (for example a result of 1 will be turned into the group _1).

Standard local variables are available as well as local variables created with the Attribute Create SOP.

Locals

Note

Variable names ending with 2 refer to the geometry from the second input, if applicable. For example, PT2 is the current point number from the second input.

AGE

The seconds a particle in the template has been alive.

ARC

Arc length distance from root in the L-systems.

AREA

The surface area of the primitive (created by the Measure SOP).

BBX, BBY, BBZ

The point’s relative position in the bounding box.

CA

Point or vertex alpha value.

CEX, CEY, CEZ

The centroid of the geometry.

COMX, COMY, COMZ

Center of mass.

CR, CG, CB

Diffuse point or vertex color.

CREASE

Point or vertex crease weight value.

DIST

Distance from particle to last collision.

DIV

Number of divisions to build the circle swept with Polywire (created by L-systems).

DRAG

Point drag.

GEN

Generation in the L-systems.

ID

The ID of the particle in the input.

LAGE

The age of the point in the L-system computation.

LIFE

Percent of total life used (from 0 to 1).

LOD

Level of detail.

MAPU, MAPV, MAPW

Point or vertex texture coordinates.

MASS

Point mass.

MAT

The string name of the current material (the value of the shop_material attribute).

MAXLAYER

The number of layers that are considered active for display.

NPT

The total number of points in the template geometry.

NX, NY, NZ

Normal vector.

PERIMETER

The perimeter of the primitive (created by the Measure SOP).

PR, NPR

Primitive number & total number of primitives.

PSCALE

Particle Scale.

PT

The point number of the currently processed point.

RESTX, RESTY, RESTZ

The rest position.

SEGS

Number of segments to divide a curve up into in Polywire (created by L-systems).

SIZEX, SIZEY, SIZEZ

The size of the bounding box.

SPRINGK

Elasticity of a point.

TENSION

Spring tension of an edge.

TX, TY, TZ

Point position.

TW

See WEIGHT.

UPX, UPY, UPZ

The vector pointed in the up direction.

VTX, NVTX

Vertex number & total number of vertices.

VX, VY, VZ

Velocity direction.

WEIGHT

Point spline weight.

WIDTH

The width of the curve. Used by mantra for rendering curves & polywire for generating trees.

XMIN, XMAX

The X extents of the bounding box of the geometry.

YMIN, YMAX

The Y extents of the bounding box of the geometry.

ZMIN, ZMAX

The Z extents of the bounding box of the geometry.

Parameters

Group

The primitives or points considered for the operation.

Entity

The type of the entity specified in the group parameter.

Geometry Type

The type of primitives to consider for this operation. Only applicable when Entity is set to Primitives.

Rule

The rule with which to evaluate each primitive or point. The result of the rule is the name of the group in which the primitive or point will be placed.

Examples

PartitionBall Example for Partition geometry node

This example demonstrates how to break geometry in a DOPs simulation using the Partition SOP to determine the DOP Objects.

See also

Partition