## Cluster

Object Hierarchy | Related C++ Class: Cluster

### Inheritance

SIObject

ProjectItem

SceneItem

Cluster

### Description

A cluster represents a set of components on a Geometry. For example, the polygons of the left arm of a human model might be grouped together by creating a cluster.
A cluster has a SIObject.Type which corresponds to the component type that it contains, (pnt, knot, poly). A geometry can have multiple clusters, including clusters of different types. Any particular component might be included in multiple clusters. The ClusterTypes that are supported on a geometry depend on the type of object. For example only NurbsSurface or NurbsCurve can have a siKnotCluster.
Clusters can be created on the geometry of a ParticleCloud. These clusters are of type siVertexCluster but they contain Particles.
A cluster that includes all the components of a particular type is said to be "always complete", which you can verify with the Cluster.IsAlwaysComplete method. An always-complete cluster always covers all components of the geometry, even when components are added by a modeling operation; however, notice that a cluster which covers all components of a geometry is not necessarily always-complete. Other clusters may contain a subset of components. In all cases the indices of the components in the cluster do not directly match the indices of the component on the geometry. The mapping between cluster indices and geometry indices is available through Cluster.Elements and Cluster.FindIndices.
Clusters are useful for storing per-component data with a ClusterProperty or UserDataMap. Clusters can also have their own CustomProperty objects. All these properties can be created with SceneItem.AddProperty and enumerated with SceneItem.LocalProperties. Notice that some types of ClusterProperty require the cluster to be always complete.
Warning: Operations that change the geometry, for example adding an edge to a mesh, can result in the cluster growing or shrinking.
Note: As of v5.0, the base property SIObject.Parent called on a Cluster object returns a Primitive instead of an X3DObject.

### Methods

AddCustomOp | AddCustomProperty | AddICEAttribute | AddMaterial
AddProperty | AddScriptedOp | AddScriptedOpFromFile | AnimatedParameters2
ApplyEnvelope | BelongsTo | CreateSubComponent | EvaluateAt
FindIndex | FindIndices | GetICEAttributeFromName | GetLocalPropertyFromName
GetLocalPropertyFromName2 | GetPropertyFromName | GetPropertyFromName2 | GetStaticKinematicStates
HasStaticKinematicState | IsA | IsAlwaysComplete | IsAnimated2
IsClassOf | IsEqualTo | IsKindOf | IsLocked
IsSelected | LockOwners | RemoveICEAttribute | SetAsSelected
SetCapabilityFlag | SetLock | SetMaterial | TaggedParameters
UnSetLock |  |  |

### Properties

Application | BranchFlag | Capabilities | Categories
CenterReference | Elements | Envelopes | EvaluationID
Families | FullName | Help | HierarchicalEvaluationID
ICEAttributes | LocalProperties | LockLevel | LockMasters
LockType | Material | Model | Name
NestedObjects | ObjectID | Origin | OriginPath
Owners | PPGLayout | Parameters | Parent
Parent3DObject | Properties | Selected | Type

### Examples

#### 1. VBScript Example

    '
    '       This example shows how to create many different cluster types.
    '       It also shows how to find all clusters in a scene
    '
    NewScene ,false
    set oRoot = Application.ActiveProject.ActiveScene.Root
    set grid = oRoot.AddGeometry("Grid","MeshSurface")
    set gridGeometry = grid.ActivePrimitive.Geometry
    'Only certain types makes sense on a MeshSurface
    'This cluster we will create as a subset of the vertices
    gridGeometry.AddCluster siVertexCluster,"PntCluster",Array(1,4,7,10,13,16,19,22)
    'The rest we will create as complete clusters
    gridGeometry.AddCluster siPolygonCluster,"PolygonC"
    gridGeometry.AddCluster siEdgeCluster
    gridGeometry.AddCluster siSampledPointCluster
    'A different set makes sense with Nurbs
    set torus = oRoot.AddGeometry("Torus","NurbsSurface")
    set torusGeometry = torus.ActivePrimitive.Geometry
    torusGeometry.AddCluster siVertexCluster,"PntCluster"
    torusGeometry.AddCluster siSampledPointCluster
    torusGeometry.AddCluster siSurfaceCurveCluster
    torusGeometry.AddCluster siKnotCurveUCluster
    torusGeometry.AddCluster siKnotCurveVCluster
    torusGeometry.AddCluster siBoundaryCluster
    torusGeometry.AddCluster siKnotCluster
    torusGeometry.AddCluster siTrimCurveCluster
    torusGeometry.AddCluster siIsoLineUCluster
    torusGeometry.AddCluster siIsoLineVCluster
    torusGeometry.AddCluster siSubSurfaceCluster
    set circle = oRoot.AddGeometry("Circle","NurbsCurve")
    set circleGeometry = circle.ActivePrimitive.Geometry
    circleGeometry.AddCluster siIsoPointCluster
    circleGeometry.AddCluster siVertexCluster,"PntCluster"
    circleGeometry.AddCluster siKnotCluster
    set particleCloud = CreateParticleCloud().Item(0)
    particleCloud.ActivePrimitive.Geometry.AddCluster siVertexCluster, "MyParticles"
    ' Now traverse the scene finding all the clusters
    logmessage "Clusters in Scene......................"
    set oSceneObjs = ActiveSceneRoot.FindChildren()
    for each oItem in oSceneObjs
            'Use error handling to skip over the objects that don't
            'support clusters
            on error resume next
            set oClusters = oItem.ActivePrimitive.Geometry.Clusters
            if ( err = 0 ) then
                    logmessage oItem & " has " & oClusters.Count & " Clusters: "
                    for each oCls in oClusters
                            logmessage "    " & oCls & " (type: " & oCls.Type & ")"
                    next
            end if
    next
    'The output of this script is:
    'INFO : "Clusters in Scene......................"
    'INFO : "grid has 4 Clusters: "
    'INFO : "    grid.polymsh.cls.PntCluster (type: pnt)"
    'INFO : "    grid.polymsh.cls.edge.clslist.Edge (type: edge)"
    'INFO : "    grid.polymsh.cls.PolygonC (type: poly)"
    'INFO : "    grid.polymsh.cls.sample.clslist.Sample (type: sample)"
    'INFO : "torus has 11 Clusters: "
    'INFO : "    torus.surfmsh.cls.V_Knot_Curve (type: knotcrvv)"
    'INFO : "    torus.surfmsh.cls.U_Knot_Curve (type: knotcrvu)"
    'INFO : "    torus.surfmsh.cls.sample.clslist.Sample (type: sample)"
    'INFO : "    torus.surfmsh.cls.PntCluster (type: pnt)"
    'INFO : "    torus.surfmsh.cls.Surface_Curve (type: srfcrv)"
    'INFO : "    torus.surfmsh.cls.V_Isoline (type: isolinev)"
    'INFO : "    torus.surfmsh.cls.knot.clslist.Knot (type: knot)"
    'INFO : "    torus.surfmsh.cls.Boundary (type: bndry)"
    'INFO : "    torus.surfmsh.cls.Subsurface (type: subsrf)"
    'INFO : "    torus.surfmsh.cls.U_Isoline (type: isolineu)"
    'INFO : "    torus.surfmsh.cls.Trim_Curve (type: trimcrv)"
    'INFO : "circle has 3 Clusters: "
    'INFO : "    circle.crvlist.cls.Isopoint (type: isopnt)"
    'INFO : "    circle.crvlist.cls.PntCluster (type: pnt)"
    'INFO : "    circle.crvlist.cls.knot.clslist.Knot (type: knot)"
    'INFO : "cloud has 1 Clusters: "
    'INFO : "    cloud.cloud.cls.MyParticles (type: pnt)"

#### 2. JScript Example

    //Step 1: Simulate the user creating a scene and selecting
    //some points on a grid
    var oGrid = ActiveSceneRoot.AddGeometry( "Grid", "MeshSurface" ) ;
    SelectObj( oGrid ) ;
    ActivateVertexSelTool();
    AddToSelection( oGrid.Name + ".pnt[0-8]", null, true);
    //Step 2: Get the selected components using OM
    var oSubComponent = Selection(0).SubComponent ;
    //Expect that 9 components were selected
    logmessage( oSubComponent.ComponentCollection.Count ) ;
    //Step 3: it is simple to create a cluster
    var oCluster = oSubComponent.CreateCluster() ;
    logmessage( oCluster.FullName  ) ;
    //Output of this example:
    //INFO : "9"
    //INFO : "grid.polymsh.cls.Point"

### See Also

ClusterProperty Geometry.AddCluster Geometry.Clusters Geometry.SaveShapeKey