Houdini 20.5 Nodes Geometry nodes

Vellum Post-Process geometry node

Applies common post-processing effects to the result of Vellum solves.

Since 17.0

The Vellum Post-Process node provides common post-processing operations for Vellum solvers. It can fuse the welds to be shared points, smooth the geometry, and subdivide the mesh. In addition, if constraints are provided it can visualize the constraint energies, very useful when inspecting a simulation that has been saved to disk.

Parameters

Operations

Apply Welds

Fuse all the points that have been implicitly welded with weld and branchweld attributes.

Smooth

Blur Group

Points to apply spatial blurring effects to.

Spatial Blur

Amount of blurring to apply. Points move to the average of their neighbors. This can smooth out unwanted spikes in the cloth.

Subdivision

A low res cloth can be up-resed after the solve by smoothly subdividing it. Non-manifold patches will be split prior to subdividing to ensure gaps aren’t formed.

None

No subdivsion is done.

Catmull-Clark

Catmull-Clark subdivision, which works best for quadrilaterals, is done.

Loop

Loop subdivision, which works best for triangles, is done.

Subdivision Depth

Number of rounds of subdivision to perform.

Collision Correction

Detangle

The smooth and subdividing may introduce collisions. Detangling moves points to avoid such introduced collisions. Note each point moves independently, so this can result in ugly geometry if large changes are required.

Self Collisions

Check for self-collisions.

Passes

Number of iterations of detangling to perform.

Default Thickness

If no pscale is present, this is used for the thickness of the objects.

Shape Match Rigidity

Ensure that all pieces of geometry constrained by a Shape Match constraint remain rigid by blending in the specified amount of rigid motion.

Thicken

Extrude by Thickness

Extrude cloth sheets in both directions and thickens wires into tubes.

Thickness Scale

Multiplier to scale pscale by for the extrusion amount.

Wire Divisions

Number of divisions to use in the generated tube.

Visualize

Show Collision

Visualize the third input, the collision geometry, as blue wireframe.

Show Guide Geometry

Display the constraint guide geometry.

Geometry

Thickness

Draw spheres for the pscale of the geometry. If the geometry has already solved it may have set the overlap_self attribute, if so, the actual effective thickness is drawn in cyan. This is useful to detect if the original thickness was too high - if so the extra thickness will be ignored by the simulation and just slow down the collisions.

Extrude

Draw the thickness by offsetting the geometry in opposite directions rather than by using spheres.

Failed Self Collision

Draw failed self collisions as red spheres. These points will no longer collide with their own geometry, nor will any edge or triangle attached to them.

Failed External Collision

Draw failed external collisions as orange spheres. These points will no longer collide with external geometry, nor will any edge or triangle attached to them.

Welds

Draw which points have been semantically fused together with the weld attribute. These can be broken during the solve using the auto break options, or by setting weld to -1.

Radius Scale

Because the thickness may be small, the visualization spheres can sometimes be lost. This scales the visualization spheres allowing them to be readily seen.

Constraints

Group

Constraints are often added to different groups. This allows you to isolate one particular group to visualize.

Pin to Target

Draw spheres over points pinned to the target animation.

Stitch Points

Draw stitch constraints of points stitched together.

Attach to Geometry

Draw attachment constraints for points attached to external geometry.

Radius

The constraint guides are not scaled by the thickness of the object, so this provides an absolute scale for their size.

Visualization

False Color Mode

Visualize properties of the constraints using a blue-to-red infrared coloring.

None

Leave the original colors.

Stretch Stress

Color according to the maximum stretching force applied by the constraints.

Bend Stress

Color according to the maximum bending force applied by the constraints.

Stretch Distance

Color according to how far constraints are stretched.

Stretch Ratio

Color according the ratio between original and current stretch.

Bend Angle

Color according to how many degrees the bend angle has deviated.

Stretch Plastic Flow

Color according to how much the stretch plastic flow has been triggered.

Bend Plastic Flow

Color according to how much the bend plastic flow has been triggered.

Volume Stress

Color according to the maximum volumetric force applied by the constraints.

Volume Distance

Color according to how far volumetric constraints have expanded from their rest state.

Volume Ratio

Color according the ratio between volumetric expansion and the rest state.

Display Visualization Geometry

Toggles if the simulation geometry is false-colored in addition to the constraints.

Max Stretch Stress

Scales the maximum stretch stress to be the maximum coloration.

Max Bend Stress

Scales the maximum bend stress to be the maximum coloration.

Max Stretch Distance

Sets the maximum stretch distance to be the maximum coloration.

Max Stretch Ratio

Sets the maximum stretch ratio to be the maximum coloration.

Max Bend Angle

Sets the maximum bend angle to be the maximum coloration.

Max Stretch Plastic Flow

Sets the maximum stretch plastic flow to be the maximum coloration.

Max Bend Plastic Flow

Sets the maximum bend plastic flow to be the maximum coloration.

Max Volume Stress

Scales the maximum volume stress to be the maximum coloration.

Max Volume Distance

Scales the maximum volume distance to be the maximum coloration.

Max Volume Ratio

Scales the maximum volume ratio to be the maximum coloration.

Output Attributes

Output various point attributes on the simulation geometry, calculated from the constraints applied to those points. These values are the many of the same ones that can be visualized in the Visualization section, but output to the geometry for further processing and/or shading.

Stretch Stress

The stretching force applied by the constraints.

Bend Stress

The bending force applied by the constraints.

Stretch Distance

How far constraints are stretched.

Stretch Ratio

The ratio between original and current stretch.

Bend Angle

How many degrees the bend angle has deviated.

Stretch Plastic Flow

How much the stretch plastic flow has been triggered.

Bend Plastic Flow

How much the bend plastic flow has been triggered.

Volume Stress

The volumetric force applied by the constraints.

Volume Distance

How far volumetric constraints have expanded from their rest state.

Volume Ratio

The ratio between volumetric expansion and the rest state.

See also

Geometry nodes