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Elements can occur in more than one group. Groups are used in many parts of the Parameter Editor to specify which portions of input geometry you wish an operator to act upon.
You can also create ordered groups. To do so, enable the Ordered checkbox.
This operator is very powerful and is ideal for combining geometry that is similar. For example, all the primitive geometry of a group of door structures for a three-dimensional architectural model could be grouped together and consequently scaled and re-sized together using a Transform node. Works in conjunction with most filter nodes.
Group name specifiers become very powerful when you use pattern matching in your group specifiers.
Using Group Geometry
Creating groups based on point attributes
You can create groups based on point/primitive attributes using the Combine tab and group specification syntax.
For example, to create a group containing all points with Y position greater than
In the parameter editor for the Group node, click the Combine tab.
In the Group field (below Combine entity), set the left side to the name of the group you want to create, click the equal button in the middle, and set the right side to
In this example,
P is the name of the position vector attribute,
.y takes the Y component of the vector, and
>0 selects points where the component is greater than 0. See the
@ group specification syntax for more information. Note that the
@ syntax does not allow spaces.
The geometry on which to create the groups.
Bounding geometry. (Only works for point groups when selecting by bounding geometry.)
Accepts all geometry.
The name of the group to create.
Whether to create a primitive or point group.
What sort of primitives to allow in the group.
How to resolve collisions between the newly created group with an already existing group.
The newly created group will replace the existing group.
Union With Existing
The group will consist of the union between the newly created group and the already existing group.
Intersect With Existing
The group will consist of the intersection between the newly created group and the already existing group.
Subtract From Existing
The group will consist of the contents of the already existing group that are not also in the newly created group.
Enables grouping by number.
Orders the points/primitives in the group in the order they are entered. Useful when skinning.
Groups by a pattern, a range, or an expression.
This is evaluated for every point or primitive. If it is true, the element is added to the group. It supports all the local variables of the Point and Primitive operations.
Edge groups are currently not supported with expressions.
Points and primitives that match the expression will be in the final group regardless of the other tabs.
Enter the pattern to be grouped.
This field also accepts edge patterns:
All edges in primitive number n.
Point number n / edges with point number n.
Edge number m of primitive n.
Edges between point number a and point number b.
The start of the range to be grouped. For edge groups the ranges will be interpreted as primitive indices.
The end of the range to be grouped. For edge groups the ranges will be interpreted as primitive indices.
Group every # of # primitives/points. Edges are grouped here by primitive numbers.
Enable grouping by bounding volume.
Shape of bounding volume.
Size of bounding volume.
Center of bounding volume.
The iso surface of volume to do the grouping with. Points whose volume value are less than this will be grouped. A value of 0 is good for SDF volumes. For fog volumes, use a value of 0.5 and turn on Invert Volumes for best results.
Inverts sense of being inside the volume.
Include Entities Not Wholly Contained
Include entities that are not wholly contained within the bounding object.
Enable grouping by normal.
Normal direction to group by.
Deviation from the direction to allow in the group.
Groups primitives facing away from this object.
Unlike grouping by normal this operation will remove items that satisfy the backface condition from any group created via another tab. If no other group is created, this operation will add satisfying items.
Groups polygons that are non-planar given the tolerance.
Polygons that are non-planar will be added to the group regardless of the other tabs.
Points, primitives, and edges that match the edge grouping rules will be in the final group regardless of the other tabs.
Enables edge grouping.
Min Edge Angle
Groups primitives with at least this angle between their normals. For edge groups, an edge is included in the group if the two primitives that share it satisfy this angle requirement.
Max Edge Angle
Groups primitives with at most this angle between their normals. For edge groups, an edge is included in the group if the two primitives that share it satisfy this angle requirement.
Edge Angle Uses Angle Between Edges
For edge groups only, when this option is checked edges are included in the group based on the angle between themselves, instead of the angle between the primitives that share them.
Each edge is compared against all other edges that share a point with it.
Min Edge Length
Groups edges that have at least this length.
Max Edge Length
Groups edges that have at most this length.
Number of edges away from the points in Point Group.
Points around which group is centered.
Create Boundary Groups
Create groups containing surface boundary points.
Combines different groups based on boolean operators.
The type of group on which to operate. While it can usually be determined from the given groups, this parameter is useful to resolve ambiguous cases.
This section allows you to create a new group out of existing groups. Enter the group to operate on or create in the first field and the name of the existing group in the field on the other side of the buttons. You can either include the contents of the other group by selecting Equals or everything that is not the other group by selecting Equals all but. Use the fields below to combine additional groups.
Renames an existing group to something else. When renaming groups, you can use wildcards to rename several groups that match the specified pattern. For more information about the pattern substitution rules, please see Attrib String Edit.
Group to rename.
New name of group.
Converts between different types of groups. When converting groups, you can use wildcards to convert several groups that match the specified pattern. For more information about the pattern substitution rules, please see Attrib String Edit.
Source group type.
Newly created group type.
Group to convert.
The new name of the converted group. Leave this empty to keep the name of the original group.
Preserves original geometry.
Omit Entities in New Group not Wholly Contained in the Old Group
This option allows only primitives that have all of their points or edges in the original point group to be included in the resulting primitive group, when converting from a point group or an edge group to a primitive group.
The same thing applies when converting from a point group or a primitive group to an edge group. Only edges with both points in the original point group will be added to the new group.
Deletes an existing group.
Group to delete.
(number of points/primitives/edges) -1
See list of standard variables.
This example demonstrates how feature edges of your object can be preserved during a polyreduce by using an Edge Group.