Houdini 20.5 Nodes Geometry nodes

Attribute Mirror geometry node

Copies and flips attributes from one side of a mirror to the other side.

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This node copies and flips attributes from one side of the geometry to another. There are different options in the Mirroring Method menu to mirror using a Plane, Topology, or an existing mirror Mapping.

Example

Use the texturing tools to texture one side of a symmetric model (such as a human-like character) and then use AttribMirror to automatically mirror the UV texture coordinates to the opposite side of the model.

Parameters

General

Group

A subset of the geometry to use as a source or destination for the mirror.

Group Type

The type of elements referenced in the Group field.

Use Group As

As a source, the elements of the group are mirrored onto the rest of the geometry across the mirror. As a destination, the elements of the rest of the geometry are mirrored onto elements of the group across the mirror.

Attribute

Attribute to mirror. Color and Texture UV are provided. Other attributes can be specified by selecting Other Attribute.

Attribute Names

When Other Attribute is selected, these are the names of the attributes to mirror. Use a space to separate attributes. Each of the attributes must exist on the geometry elements specified by the Group Type parameter. If no attributes are specified, all attributes are copied.

Mirror

Mirroring Method

This determines the method for establishing a mirror between two sides of the geometry.

Plane

A geometry on the model’s source side of the model and the closest mirrored geometry on the destination side.

The closeness of geometry is defined by position. A primitive’s position is the center of its bounding box. Vertex attributes are mirrored by first finding a mirror primitive, and then finding a mirror point within that primitive.

This mirror plane is on the destination side. To mirror two geometry elements, one must be on the source side and the other on the destination side.

Topology

A geometry’s vertices outwards from the mirroring edges in opposite directions. A vertex on one side mirrors the vertex on the other side. You can also mirror the points being shared by this vertex pair and between the primitives of each vertex.

Points that lie on the mirror edge are not considered to be on either side of the mirror.

Use Mapping

The mirror is recreated from the pairs read from the Element Mapping Name attribute, and the destination side of the mirror is marked by the elements included in the Destination Group.

Tolerance

Create a mirrored geometry only if the mirrored distance lies within this tolerance.

Origin

The origin of the reflection plane.

Distance

Distance to move the reflection plane.

Direction

Direction of the reflection plane’s normal.

Mirroring Edge

This specifies the group of edges to use as the mirror when the Mirroring Method is Topology. You can specify multiple disjoint sets of mirroring edges.

Source Side Hint

Specifies the group of primitives on the source side of the geometry when the Mirroring Method is Topology. If no hints are provided, or if there are contradicting hints, then the lowest primitive number is used to mark the source side.

Connectivity Attribute

When the Mirroring Method is Topology, this specifies a list of attributes whose values must be equal between an element and its neighboring element.

Element Mapping Name

When the Mirroring Method is Use Mapping, this specifies an attribute where the mirroring mapping can be read. For each destination element, the attribute’s value should equal the source element. Attribute must be an integer.

Destination Group

When the Mirroring Method is Use Mapping, this specifies a group of all elements included in the destination side. The source element is from the Element Mapping Name attribute. Some elements may not be included if there’s an invalid source element or if the mirror pair is not in Group.

Output Mapping

Element Mapping

Specifies the attribute of the element mapping For every mirror pair, this attribute will match the source element and destination element’s values.

NOTE: If the specified attribute exists already, it must be an integer. Existing attributes will be cleared before the mapping is created. Elements not included in the mirroring will have a value of -1.

Source Group

Specifies the name of a group to create which includes every element on the source side of the mirror.

Destination Group

Specifies the name of a group to create which includes every element on the destination side of the mirror.

Copy Options

Transform

Transforms the attribute. This only affects floating point attributes.

No Transformation

The attribute is copied with no change.

UVs

The attribute is mirrored using the specified UV mirror line. This is useful for texture attributes.

Vectors

When the Mirroring Method is Plane, the attribute is mirrored using the mirror plane.

When the Mirroring Method is Topology, vector attributes are mirrored by transforming using a local coordinate system. This is useful for Normal attributes.

Points

The attribute is mirrored using the mirror plane. This will include the translate components and is useful for attributes such as rest position.

String Replace

When on, performs search and replace on mirrored string values.

Search For

When String Replace is on, the string to rename in mirrored string values.

Pattern matching rules are the same as the examples in Attrib String Edit.

Replace With

When String Replace is on, mirrored strings that match the Search For pattern are replaced with this value.

Pattern matching rules are the same as the examples in Attrib String Edit.

See also

Geometry nodes