Houdini 20.0 Nodes Geometry nodes

Wire Capture geometry node

Captures surfaces to a wire, allowing you to edit the wire to deform the surface.

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WireCapture works in conjunction with the WireDeform SOP by assigning wire capture weights to points that fall within a given radius of the capture primitives in the second input. The primitives are typically bezier or NURBs curves although primitives such as NURBs grids can also be used. The closer the point is to the primitives from the second input, the stronger the point is attached, ie. higher weight value.

The WireCapture SOP will not visibly change the geometry (except to possibly add point colors for feedback). To actually change the geometry, append a WireDeform SOP with the same second input.

Parameters

Group

Optional point group to assign capture weights. If empty, this implies that all points should be assigned.

Parameters

Kernel Function

Dropoff function used to convert the distance of a point to a capture primitive weight. This function is normalized according to each primitive’s capture parameters.

Treat Polygons As Lines

This specifies the behavior when the capture primitives from the second input are polygons. If this is turned on (default), then each closed polygon is treated a line primitive starting from its first vertex. If off, then each closed polygon is used as a face primitive with uv coordinates based off of the first three vertices.

Destroy Existing Weights

This specifies whether existing wire capture weight attributes are destroyed. If off, then a Blend Factor can be given to say how the new capture weights are blended with the ones already in the input geometry. Note that since the capturing is based on primitive order, all layered WireCapture SOPs which have this parameter turned off must have the same second input.

Visualize Weighting

If on, this will generate point color attributes reflecting the wire capture weights.

Visualize Type

This specifies the type of visualization used when Visualize Weighting is turned on. The Single Primitive visualize type shows the weight of each primitive along a color gradient. For points affected by multiple primitives, it will use the blended deformation weight for coloring. Multiple Primitives uses a blend of primitive colors found in the second input. If they don’t exist, then Single Primitive is used.

Visualize Mode

This specifies the gradient used for visualization.

Infra-red

Utilizes the entire color spectrum where they range from blue (0) to red (1).

White to Red

Provides a gradient which varies from white (0) to red (1).

Grayscale

Provides a gradient which ranges from black (0) to white (1).

Blackbody

Ranges from black (0) to red, yellow, then white (1).

Zero Weight Point Color

This specifies the color used for points which are not affected by any capture primitives when using the Multiple Primitive visualize type.

Capture

Initialize From Primitives

This will initialize the parameters below using the primitives found in the second input. An entry is created for each primitive using it’s primitive number.

Initialize From Groups

This will initialize the parameters below using the primitive groups found in the second input. An entry is created for each named primitive group.

Number of Primitives

This specifies the number of primitive parameter sets that we wish to capture with. Each set below has a toggle to indicate whether it should be active.

Primitive

This specifies the primitive group for which the Subgroup, Falloff Start, U Radius and Lookup, and U Range parameters apply.

Subgroup

This specifies the subgroup of points (within that listed in the Group parameter) that the parameters below are assigned.

Min/Max Weight

This gives the range to scale weight values into.

Falloff Start

This is a percentage of the current radius from which points within are assigned a weight of 1. The values for this must be between 0 and 1. It may vary along the primitive’s parametric u value if a channel exists in the Lookup parameter.

U Radius and Lookup

The two parameter components here are multiplied together to determine the effective capturing radius of the primitives. If the second component (Lookup) contains a channel, then it is evaluated using the current u value of the primitive instead of time. This allows you to specify a varying radius along the u length of the primitive. The length of the channel (ie. from its first to last key) is scaled to the u length of the primitive. Note that if the lookup curve is a channel reference, then the length of the channel must match that of the referenced one.

U Range

This specifies a u subrange of the primitive to use for capturing. The first component specifies the start u value and the second component gives the ending u value. Both of these must be between 0 and 1. Furthermore, the start value must be less than or equal to the end value.

Examples

BasicWireCapture Example for Wire Capture geometry node

This example demonstrates set up a basic wire capture network.

See also

Geometry nodes