Houdini 21.0 Nodes Geometry nodes

PolyHinge geometry node

Extrudes polygonal faces around a pivot line.

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Since 20.0

Overview

This node extrudes the polygonal faces of your geometry around the specified pivot line (hinge).

Note

When Pivot Mode is set to Edge Centric, a warning message appears if no Hinge Edge is selected.

Tip

Use the Convert Line node (not a Split or Blast) to isolate edge group outputs from this node.

Inputs

Source Geometry

This is the geometry on which to create the hinge.

Parameters

Group

The group of primitives or edges to extrude and rotate around the specified hinge.

Group Type

The type of the group to use to specify the elements to extrude.

Primitives

Treats Group as a group of primitives. Pieces are identified using primitive connectivity, and all attributes are expected on primitives.

Edges

Treats Group as a group of edges. Pieces are identified using edge connectivity, and all attributes are expected on points.

Pivot Mode

The method of specifying the hinge pivot line.

Edge Centric (default)

Computes the pivot line using the position and direction of an edge.

Position and Direction

Computes the piviot line using a fixed position and direction.

From Attributes

Computes the pivot line for each connected piece using vector attributes on the primitives or points (depending on the Group Type) for the pivot position and direction.

Hinge Edge

When Pivot Mode is set to Edge Centric, this is the group of edges that specify the hinge line. You must select at least one edge to create the hinge.

If you select more than one edge, the hinge center and direction is the direction and position halfway along the curve specified by the edges.

Pivot Pos

When Pivot Mode is set to Position and Direction, this is the position of the pivot line on the grid.

The default value is 0, 0, 0.

Pivot Direction

When Pivot Mode is set to Position and Direction, this is the direction of the pivot line.

The default value is 0, 0, 1.

Pivot Pos Attribute

When Pivot Mode is set to From Attributes, this is the vector attribute that specifies the pivot position. When the Group Type is set to Primitives this must be a primitive attribute, and when set to Edges this must be a point attribute.

The default value is pivotpos.

Pivot Dir Attribute

When Pivot Mode is set to From Attributes, this is the vector attribute that specifies the pivot direction. When the Group Type is set to Primitives this must be a primitive attribute, and when set to Edges this must be a point attribute.

The default value is pivotdir.

Hinge Angle

The angle of the hinge, in degrees. A positive value pulls the selected faces away from the surface and a negative value pushes them into the surface. Set this to By Attribute to scale the angle by a float attribute on the primitives or points (depending on the Group Type).

The hinge direction depends on the relative positions of the selected faces and the hinge pivot. A center and normal of the selected faces is computed using the respective averages of the faces' centroids and normals, weighted by the area of each face.

The default values are 45 and No Scaling.

Hinge Angle Attribute

When Hinge Angle is set to By Attribute, this is the float attribute that specifies the amount to scale the Hinge Angle. When the Group Type is set to Primitives this must be a primitive attribute, and when set to Edges this must be a point attribute.

The default value is hingeangle.

Specify Divisions

The method you use to determine the number of divisions for the Hinge Angle.

Maximum Division Angle (default)

Specifies the maximum angle for each division.

Number of Divisions

Specifies a number of divisions.

Max Division Angle

When Specify Divisions is set to Maximum Division Angle, this is the maximum angle for each division. The number of divisions is the ceiling of the Hinge Angle divided by the Max Division Angle. Set this to By Attribute to scale this value by a float attribute on the primitives or points (depending on the Group Type).

The default values are 15 and No Scaling.

Max Division Angle Attribute

When Max Division Angle is set to By Attribute, this is the float attribute that specifies the amount to scale the Max Division Angle. When the Group Type is set to Primitives this must be a primitive attribute, and when set to Edges this must be a point attribute.

The default value is maxdivangle.

Equal Division Spacing

When Specify Divisions is set to Maximum Division Angle, this equally spaces the angle divisions determined by the Hinge Angle divided by the Max Division Angle.

When turned off, all except the last division have an angle equal to the Max Division Angle value. The spacing of the last division is equal to the difference of the Hinge Angle and the total angle of the previous divisions.

Divisions

When Specify Divisions is set to Number of Divisions, this is the number of divisions for the Hinge Angle. Set this to By Attribute to scale this value by a float attribute on the primitives or points (depending on the Group Type).

The default values are 5 and No Scaling. This value must be a positive integer, and any fractions are rounded to a positive integer.

Divisions Attribute

When Divisions is set to By Attribute, this is the float attribute that specifies the amount to scale the Divisions. When the Group Type is set to Primitives this must be a primitive attribute, and when set to Edges this must be a point attribute.

The floor of the attribute value multiplied by the Divisions is used for each component.

The default value is ndivs.

Fuse Points on Hinge Pivot Line

Fuses the points on the pivot line. The points must be within the Tolerance value of the pivot line to be considered on the pivot line.

Tolerance

The maximum distance that points fuse together. Determines when to fuse points if Fuse Points on Hinge Pivot Line or Fuse Collided Points is on.

The default value is 0.001.

Inset

The height of the row of quads that’s inserted at the top and bottom of the hinge side geometry. Set this to By Attribute to scale this value by a float attribute on the primitives or points (depending on the Group Type).

The default values are 0.1 and No Scaling.

Inset Attribute

When Inset is set to By Attribute, this is the float attribute that specifies the amount to scale the Inset. When you use this parameter, the Common Inset Limit is applied per piece. When the Group Type is set to Primitives this must be a primitive attribute, and when set to Edges this must be a point attribute.

The default value is inset.

Common Inset Limit

Computes the height of all inset points first, accounting for any limits, and uses the minimal value for all inset points.

When turned off, the inset row may not be the same height all the way around and is limited by the halfway point between the top and bottom.

Fuse Collided Points

Fuses points pushed together as a result of insetting. This fuses points that either have an Inset equal to 0.0 or reach their Inset limit.

Output Front

Outputs the geometry on the top of the hinge. This geometry is the selected faces that the Hinge Angle rotates around the pivot line.

When the Group Type is set to Edges, there is no Front geometry.

Front Group

Outputs a group that contains the front geometry. Turn on Output Front to use this parameter.

The default value is front.

Output Back

Outputs the geometry on the bottom of the hinge. This geometry is the selected faces, but reversed.

When the Group Type is set to Edges, there is no Back geometry.

Back Group

Outputs a group that contains the back geometry. Turn on Output Back to use this parameter.

The default value is back.

Output Side

Outputs the geometry on the side of the hinge. This is the newly constructed polygonal geometry that bridges the front geometry and the original surface.

Reverse Side

Reverse the side geometry. This is particularly useful when hinging an edge group if the winding of the constructed topology is not expected.

Side Group

Outputs a group that contains the side geometry. Turn on Output Side to use this parameter.

The default value is side.

Inset Group

Outputs a group that contains the top and bottom row of inset primitives. Turn on Output Side and Inset to use this parameter.

The default value is inset.

Front Boundary Group

Outputs a group that contains the boundary edges of the front primitives. Turn on Output Front or Output Side to use this parameter.

The default value is frontboundary.

Back Boundary Group

Outputs a group that contains the boundary edges of the back primitives.

The default value is backboundary.

Examples

PolyHingeBasic Example for PolyHinge geometry node

This example shows how to use the polyhinge SOP to extrude a group of faces around a pivot edge.

PolyHingeEdge Example for PolyHinge geometry node

This example shows how to extrude an open curve around a freely positioned pivot line.

See also

Geometry nodes