# Circle geometry node

Creates open or closed arcs, circles and ellipses.

This Operation is used to create circles and ellipses. If you click and drag the mouse, it generates a circle whose radii are specified by your drag.

Clicking the mouse button on the Construction Plane without dragging places a circle with radii specified in the Parameters dialog box (default of 1) at the location of the mouse click. The radii of the default circle are aligned with the Construction Plane’s X and Y axis.

Typing Enter places a circle or ellipse whose size and position are specified in the Parameters dialog. The radii of the default circle are aligned with the Construction Plane’s X and Y axis.

If an odd aspect ratio was previously entered in the Parameters dialog, clicking and dragging produces circles which maintain that aspect ratio. This can be reset by clicking on the Reset Radii button.

## Placing a Circle in the viewer

To...Do this

Place the circle anywhere in the scene

1. Click the Circle tool on the Create tab.

2. Move the cursor into the scene view.

3. Click to place the circle anywhere in the scene view.

If you press Enter without clicking, Houdini places the circle at the origin.

Place the circle at the origin

Press ⌃ Ctrl + on the Circle tool on the shelf.

## Parameters

Primitive Type

Type of geometry created.

Orientation

Orientation of the circle.

These are the X and Y radii of the circle. Entering non-equal values in the xy fields results in elliptical shapes.

Center

Location of the center of the circle.

Rotate

Rotation about the center of the circle.

Uniform Scale

Uniform scaling.

Order

Sets the spline order when building a circle with a Bezier or NURBS curve type. The lowest order is 2 (linear); the highest is 11. Cubic curves are built by default.

Divisions

The number of points + 1 used to describe the circle. This option applies to polygons and imperfect NURBS only. The more divisions a circle has, the smoother it looks. Using three divisions makes a triangle, four divisions a diamond, five divisions a pentagon, and so on.

For open arc types, the number of points will equal Divisions + 1, and for closed arc types, Divisions + 2. The number of points on a Bezier circle will be higher than the number of divisions specified, based on the order of the Bezier curve. The # of Divisions is ignored when building a perfect (rational) NURBS or Bezier circle.

Arc Type

This menu provides you with the choices: Closed, Open Arc, Closed Arc, and Sliced Arc. The difference between these is illustrated below:

This option is disabled when building a perfect (rational) NURBS or Bezier circle. To remove a part of the rational curve later, you can use the Carve SOP.

The Closed and Closed Arc options are primarily meant for polygonal circles.

Arc Angles

When making an arc rather than a full circle, these values specify the starting and ending points of the arc in degrees. This option is disabled when building a perfect (rational) NURBS or Bezier circle.

Imperfect

Specifies whether the NURBS / Bezier circle should be built using rational or non-rational splines. A perfect circle has a rational topology: one that associates non-unit weights with certain vertices. Furthermore, a perfect circle has a predefined number and positions of CVs for any given spline order. An imperfect circle is non-rational and its number of CVs isn’t that strictly determined by its order.

Rational circles built this way yield a mathematically perfect shape; however, given their special definition, perfect circles are not always the ideal choice for further modeling of their points. Besides, they represent heavier geometry and may put more pressure both on the cpu and ram. In practice, you will find imperfect circles to be a better modeling choice, so it is advisable to build perfect circles only when perfect shapes are paramount.

## Examples

CircleExamples Example for Circle geometry node

This is an example of the different geometry types and arc types a circle can have.

Geometry types include primitives, polygons, NURBS, and Beziers.

Arc types include closed circle, open arc, closed arc, and sliced arc.

The arc examples are animated, so playback the animation to see the arcs opening.

The following examples include this node.

DynamicLights Example for Dynamics channel node

This example demonstrates how to use the Dynamics CHOP to extract impact data from a DOPs simulation, and then modify the data to control lights in the scene.

HoldLight Example for Hold channel node

This example uses the Hold CHOP in conjunction with the Dynamics CHOP to hold a light at the position of an impact from a DOPs simulation until a new impact occurs.

DensityViscosity Example for FLIP Solver dynamics node

This example demonstrates two fluids with different densities and viscosities interacting with a solid object.

This example simulates grass being pushed down by an RBD object. Fur Objects are used to represent the blades of grass and Wire Objects are used to simulate the motion. When a single Fur Object is used to represent the grass, neighbouring blades of grass will have similar motion. Additional objects with different stiffness values can be used to make the motion less uniform. When "Complex Mode" is enabled, two objects are used to represent the grass. The stiffness of each set of curves can be controlled by adjusting the "Angular Spring Constant" and "Linear Spring Constant" parameters on the corresponding Wire Objects.

This example demonstrates how to use POP Advect by Filaments to advect particles using the velocity field of a set of vortex filaments.

This example demonstrates how to use POP Advect by Volumes to advect particles using the velocity from a smoke simulation.

SphereAxisForce Example for POP Axis Force dynamics node

This example shows three different ways in which the POP Axis Force node can be used with it’s type set to sphere to control your particle simulation.

ColorVex Example for POP Color dynamics node

This example shows three different ways to use VEXpressions in your POP Color node to color your particles.

CurveForce Example for POP Curve Force dynamics node

This example demonstrates the use of the POP Curve Force node to control the flow of a particle sim AND a flip fluid sim.

SwarmBall Example for POP Interact dynamics node

This example demonstrates the use of the POP Interact node to control the distance between particles and create a ball shaped swarm.

LookatTarget Example for POP Lookat dynamics node

This interactive example demonstrates the use of the POP Lookat node. Hit play and move the green target handle around in the viewport. The cone particles will orient themselves towards the target as you move it around.

BillowyTurbine Example for Pyro Solver dynamics node

This example uses the Pyro Solver and a Smoke Object which emits billowy smoke up through a turbine (an RBD Object). The blades of the turbine are created procedurally using Copy, Circle, and Align SOPs.

Chainlinks Example for RBD Pin Constraint dynamics node

In this chain simulation, the individual chain links react to one another in an RBD sim.

This example highlights several features:

• Geometry area lights

• Attenuation ramp controls

• Surface model specular layers

The example consists of a geometry light based on a wireframe of nurbs curves. The attenuation on the light uses colored keys, allowing for different light colors to be produced at different distances from the light. The ground plane shader uses a surface model with two specular components - one wide component and another narrower glossy component to give a multi-layered appearance.

PathPathcvWorm Example for Path object node

This example shows a use for the Path and Pathcv nodes. These Path CV’s can be rotated greater than 360. They also have an initial twist function under the controls tab. This can be useful for creating a quick spine.

Volume Rendering - File Referenced Smoke Example for Mantra render node

Volume rendering is a rendering approach that allows high-quality, integrated rendering of volumetric effects like smoke, clouds, spray, and fire.

Volume rendering is suitable for rendering many types of volumetric effects. Scenes that are particularly suited to rendering with mantra volumes include:

• Detailed "hero" clouds, smoke, or fire

• Fields of instanced clouds, smoke, or fire

Scenes where volume rendering may not be quite so applicable include:

• Scenes with a single uniform fog

In this particular example, a bgeo file (1 frame only) was exported from a fluid simulation of smoke and is now referenced using the File SOP. A material using VEX Volume Cloud is assigned to this volumetric data at the top level of the Volume Object. To see this scene in shaded mode, ensure that HOUDINI_OGL_ENABLE_SHADERS is set to 1 in the environment variables.

## Controlling Quality/Performance

Volume rendering uses ray marching to step through volumes. Ray marching generates shading points in the volume by uniformly stepping along rays for each pixel in the image. There are two ways to change the quality and speed of the volume ray marching:

1. The samples parameter on the Sampling tab of the mantra ROP. More pixel samples will produce more ray marches within that pixel leading to higher quality. Using more pixel samples will also improve antialiasing and motion blur quality for the volume.

2. The volumesteprate parameter on the Sampling tab of the mantra ROP. A larger volume step rate will produce more samples in the volume interior, improving quality and decreasing performance. A separate shadow step rate can be used for shadows.

Which parameter you should change will depend on your quality requirements for pixel antialiasing. In general, it is better to decrease the volume step size rather than increase the pixel samples because a smaller volume step size will lead to more accurate renders.

This render uses 2×2 samples and volume step rate of 1. Notice the detail in the shadows.

This render uses the same scene with 4×4 samples and a volume step rate of 0.25. The fine detail in the shadow has been lost and the volume is somewhat more transparent. The quality level is approximately the same.

Down Hill Lava Flow Example for Material shader node

In this file we create a downhill lava flow with crust gathering and hardening at the base of the slope. All of the animation is achieved through the shader itself, and all of the geometry is completely static.

This network demonstrates the many uses of the Add SOP to build and manipulate geometry:

• It is used to create points in space which can then be used to create polygons using designated patterns. These polygons can be open or closed. Futhermore, each point can be animated through expressions or keyframes.

• It is used to both create points and grab points from other primitives. These points may be used in polygon creation.

• The Add SOP may be utilized to create a polygon using points extracted from another polygonal object. A Group SOP allows for the creation of the point group that will be referenced by the Add SOP.

• The Add SOP is used to create a polygon from a group of animated Null objects. An Object Merge SOP references the null points in SOPs which are then fed into an Add SOP for polygon generation. A Fit SOP, in turn, is used to create an interpolated spline from the referenced null points. The result is an animted spline.

• The Add SOP is used to generate points without creating any primitives. Also, points from other objects can be extracted through the Add SOP.

• Finally the Add SOP can additionally be used to procedurally create rows and columns.

CarveExtractCurve Example for Carve geometry node

This network is a demonstration of how the Carve SOP can be used to extract various elements of the surface geometry.

Depending on the type of geometry, the Carve SOP may be used to extract points from polygonal objects or curves from NURBS surfaces.

Furthermore, the Carve SOP uses the surface U and V information to extract the various elements, and by animating the U and V values we can create various effects as the points and curves move on the geometry surface.

CircleExamples Example for Circle geometry node

This is an example of the different geometry types and arc types a circle can have.

Geometry types include primitives, polygons, NURBS, and Beziers.

Arc types include closed circle, open arc, closed arc, and sliced arc.

The arc examples are animated, so playback the animation to see the arcs opening.

ConvToTrimSurface Example for Convert geometry node

This example shows how to create a trimmed NURBS or Bezier surface using the Convert SOP.

There are four examples contained that compare how a trimmed surface handles a texture.

• Grid Surface a simple texture map on a grid.

• Trimmed Circle Using the Trim SOP the conventional way of creating a trimmed surface using a Project SOP and a Trim SOP.

• Trimmed Circle Using the Convert SOP creates a trimmed surface using a Convert SOP.

• NURBS Surface Using the Convert SOP shows how a texture is parametrized over a surface that is not trimmed.

To get a better sense of the parameterization of the texture, turn on points and toggle between wireframe and shaded modes.

This example demonstrates how to perform boolean operations using the Cookie SOP.

In this instance, the points are consolidated using a Facet SOP and a Divide SOP is used to create a smooth surface for the Cookie SOP to operate on.

This example creates a boolean operation using the Cookie SOP.

A star geometry is created and used to subtract the shape from the sphere geometry.

CopyAttributes Example for Copy Stamp geometry node

The Copy SOP can be used for more than copying geometry. In this example, the Copy SOP is used to transfer color attributes from the template geometry (or point) to the copied geometry.

A polygonal sphere with color infomation is used as the source geometry. A point with a color attribute (Cd) is extracted from the sphere and used as a template by the Copy SOP. Then the Copy SOP transfers the color infomation to a copied polygonal circle.

StampStars Example for Copy Stamp geometry node

This example demonstrates the power of the Copy SOP’s Stamp operation.

Here, a Copy SOP is used to copy a circle onto the points of a sphere. The Stamp operation then applies various modifications to those copies based on division, scale, color, and extrusion. This results in the generation of a randomized variety of "stars".

Starting with a simple circle, a large number of variations are created using in the copies through the use of Stamping with expressions.

CreepBlob Example for Creep geometry node

This example shows how to creep metaballs on a surface. In this case, the surface is a contorted tube and the metaballs look like a "blob" being pushed through the tract.

A tube is created and used as the creep surface. A circle is created by carving a profile out from that same tube. The circle is then animated with a Creep SOP down the length of the tube.

Metaballs are attached to the points on that carved circle to create the "blob".

CreepParticleTubeA Example for Creep geometry node

This example shows two different ways in which particles can be crept on a surface. In this case, the surface is a contorted tube.

One version shows how particles are crept inside the surface, the other shows how particles are crept outside the surface. This is done by changing the z scale in the Creep SOP, which offsets the particles perpendicular to the surface.

The particles are birthed from a circle that is carved from the tube geometry.

DeleteFan Example for Delete geometry node

The Delete SOP can be used to delete primitives through various methods.

Primitives can be deleted using a pattern range to create interesting objects, such as the fan in this example.

EdgeCollapseBasic Example for Edge Collapse geometry node

The Edge Collapse SOP simply allows the deletion of edges, as shown in this example. Point numbers are rearranged to accommodate the missing edge.

EdgeFlipBasic Example for Edge Flip geometry node

This example demonstrates how you can use the EdgeFlip SOP to flip a selected edge on a surface.

An edge is created on a polygon using the Polysplit SOP, then rotated using the EdgeFlip SOP.

FurBallWorkflow Example for Fur geometry node

This example demonstrates how the Fur SOP and Mantra Fur Procedural can be applied to an animated skin geometry. CVEX shaders are used to apply a custom look to the hairs based upon attributes assigned to the geometry.

HoleBasic Example for Hole geometry node

This file demonstrates the Hole SOP.

There are four examples given of the Hole SOP, how to add holes to a surface, or remove them.

This example demonstrates how to have multiple shading layers with different uv sets using the Layer SOP and the VEX Layered Surface SHOP.

LSystemMaster Example for L-System geometry node

The LSystems SOP allows for the definition of complex shapes through the use of iteration. It uses a mathematical language in which an initial string of characters is evaluated repeatedly, and the results are used to generate geometry. The result of each evaluation becomes the basis for the next iteration of geometry, giving the illusion of growth.

The example networks located in this demonstration should be enough to get you started writing custom LSystem rules.

However, anyone seriously interested in creating LSystems should obtain the book:

The Algorithmic Beauty of Plants, Przemyslaw Prusinkiewicz and Aristid Lindenmayer

For a full list of LSystem commands, see the Houdini documentation.

LsystemBuilding Example for L-System geometry node

This example demonstrates how to use the L-System SOP to generate buildings with windows.

This example file demonstrates using the Metaball and Force SOPs to affect particles generated by the Particle SOP.

Particles are birthed from the origin and shot towards a still metaball. The metaball has a Force SOP applied to it causing the particles, upon reaching the metaball, to spread away from it out into space.

The Particle SOP enables the creation of particles at the SOP level and allows those particles to directly interact with geometry. Furthermore, these particles are in turn treated as point geometry.

In this example, particles are both crept along and collided with a collision tube object. It is possible to also manipulate and control particles in SOPs through the adjustment of point normals (including those of the particles).

AimPointNormals Example for Point geometry node

This is an example of how to use the Point SOP to orient point normals along a path. This allows for control over the orientation of geometry when copied onto points.

Points are extracted along a spiral on a per frame basis using an expression in the Carve SOP. A cone is copied to these points sequentially and results in an animation along the path.

BridgeCurvesandPrims Example for Poly Bridge geometry node

This contains two examples of how to use the Bridge SOP.

The first example illustrates how to use the Bridge SOP on projected and trimmed curves. The second illustrates how to use the Bridge SOP on two carved primitives.

Press Play to see an animated version of the Bridge over Two Carves.

FlagProfiles Example for Profile geometry node

This example shows how to use the Project SOP to create a profile on a surface.

The Profile SOP is then used to extract the profile from the surface or remap the profile on it. It also shows how the profile will animate with the surface or independent of it.

ProjectCurve Example for Project geometry node

This example shows the Project SOP projecting a Circle onto a Tube geometry.

By projecting along a vector the Circle profile is attached to the tube. With the use of a Trim SOP the profile can then be used to cut holes in the Tube.

RayWrap Example for Ray geometry node

The Ray SOP projects one object over the surface contours of another.

It does so by calculating the collisions of the projected object’s normals with the surface geometry of the collided object.

In this example, a Grid is wrapped over the surface of a deformed Sphere using the Ray SOP.

A Facet SOP is used to correct the normals of the wrapped Grid after it is deformed over the surface.

BasicRest Example for Rest Position geometry node

The Rest Position SOP creates an attribute based on the surface normals that allows a shader to stick to a deforming surface.

All primitives support the rest attribute, but, in the case of quadric primitives (circle, tube, sphere and metaball primitives), the rest position is only translational. This means that rest normals will not work correctly for these primitive types either.

Use the Rest Position SOP only when you are deforming your geometry and you are assigning volumetric or solid materials/patterns in your shader.

Rest normals are required if feathering is used on polygons and meshes in Mantra. NURBs/Beziers will use the rest position to compute the correct resting normals.

It will be necessary to render the setup in order to see the effect.

BasicRevolve Example for Revolve geometry node

This example demonstrates the Revolve SOP’s ability to create geometry by spinning curves and surfaces around any described axis. Simple objects, such as a torus and a vase, are generated by the Revolve SOP and user-defined inputs.

This file also shows off how different geometry types react to different Revolve SOP parameter changes.

DoorWithPolkaDots Example for Scatter geometry node

This example demonstrates how you can use the Scatter SOP to scatter points that stay consistent through topology changes like remodelling the input geometry or breaking it. It does this by using the option to scatter in texture space.

SpottedSoccerBalls Example for Scatter geometry node

This example demonstrates how you can use the Scatter SOP to scatter points that stay consistent when separate pieces are added or removed. It does this by using the option to use custom random seeds for each primitive.

SkinBasic Example for Skin geometry node

This is a demonstration of using the Skin SOP to create complex forms by creating surfaces between one or two input geometries.

It also demonstrates how the Skin SOP can interpret between different geometry types and varying point numbers.

SweepBasic Example for Sweep geometry node

This example demonstrates how the Sweep SOP copies geometry onto the points of a curve.

The Sweep SOP is unique in that it automatically places the copied geometry perpendicular to the backbone it is copied to. Variations such as the Cross Section’s scale can be adjusted using expressions.

SweepCurve Example for Sweep geometry node

This network contains an example of the Sweep SOP. A NURBS curve and NURBS circles are used as the backbone and the cross section geometries of the sweep operation respectively.

By controling the scaling of the cross section geometry in the Sweep SOP various effects can be acheived. Finally, a Skin SOP completes the form by using the swept geometry as a kind of skeleton.

SweepDome Example for Sweep geometry node

In this example the Sweep SOP a grid is used as the backbone of a sweep operation with arcs (created by a Circle SOP) as the hull (cross sections) of the sweep object.

The final sweep object is then skinned with a Skin SOP to create the dome geometry.

WigglyWorm Example for Sweep geometry node

This network demonstrates how the Sweep SOP can be used to construct geometry that is easily deformable. The Sweep SOP requires a backbone and cross section geometry.

Through a sin() function an expression is created to animate the backbone for a slithering effect. Then the circles are copied at every point on the backbone to create the skeleton of the worm. Finally, a simple skin operation completes the worm body.

Chainmail Example for Triangulate 2D geometry node

This example demonstrates advanced use of the new Triangulate2D SOP to create chainmail links.

volumeresample Example for Volume Resample geometry node

This example shows how to use the Volume Resample SOP to increase and decrease the resolution of a volume. It also shows how the different sampling options affect the quality of the resulting volume.

Wireblend Example for Wire Blend geometry node

The Wire Blend SOP is used to blend curves from input geometry. In this case, three input morph targets are used by the Wire Blend SOP with the Differencing and option checked. The blend values of the input morphs are keyframed for specific effects. Play the animation to see the results.

RaytraceVopShader Example for Ray Trace VOP node

This example demonstrates a simple ray traced shader using a vop vex network. To modify the shader properties, create a properties shader in the material and connect it to the output shaders node. You can then add rendering parameters to the properties node. For example to control the number of reflection bounces, you would add the reflect limit parameter.

# Geometry nodes

• Removes elements while trying to maintain the overall appearance.

• Creates Points or Polygons, or adds points/polys to an input.

• Creates agent primitives.

• Adds new clips to agent primitives.

• Adds new clips to agent primitives.

• Defines how agents' animation clips should be played back.

• Creates geometry describing possible transitions between animation clips.

• Creates a new agent layer that is suitable for collision detection.

• Creates point attributes that specify the rotation limits of an agent’s joints.

• Builds a constraint network to hold an agent’s limbs together.

• Writes agent definition files to disk.

• Edits properties of agent primitives.

• Adds a new layer to agent primitives.

• Adjusts the head of an agent to look at a specific object or position.

• Adjusts the head of an agent to look at a specific object or position.

• Adds various common point attributes to agents for use by other crowd nodes.

• Adds various common point attributes to agents for use by other crowd nodes.

• Provides simple proxy geometry for an agent.

• Creates parent-child relationships between agents.

• Adapts agents' legs to conform to terrain and prevent the feet from sliding.

• Adds new transform groups to agent primitives.

• Extracts geometry from agent primitives.

• Extracts geometry from agent primitives for a Vellum simulation.

• Loads the geometry from an Alembic scene archive (.abc) file into a geometry network.

• Creates a geometry group for Alembic primitives.

• Modifies intrinsic properties of Alembic primitives.

• Aligns a group of primitives to each other or to an auxiliary input.

• Cleans up a series of break operations and creates the resulting pieces.

• Blurs out (or "relaxes") points in a mesh or a point cloud.

• Changes the size/precision Houdini uses to store an attribute.

• Composites vertex, point, primitive, and/or detail attributes between two or more selections.

• Copies attributes between groups of vertices, points, or primitives.

• Adds or edits user defined attributes.

• Deletes point and primitive attributes.

• Allows simple VEX expressions to modify attributes.

• Fades a point attribute in and out over time.

• Interpolates attributes within primitives or based on explicit weights.

• Copies and flips attributes from one side of a plane to another.

• Adds noise to attributes of the incoming geometry.

• Promotes or demotes attributes from one geometry level to another.

• Generates random attribute values of various distributions.

• Renames or deletes point and primitive attributes.

• Modifies point attributes based on differences between two models.

• Edits string attribute values.

• Copies, moves, or swaps the contents of attributes.

• Transfers vertex, point, primitive, and/or detail attributes between two models.

• Transfers attributes between two geometries based on UV proximity.

• Runs a VOP network to modify geometry attributes.

• Runs a VEX snippet to modify attribute values.

• Samples texture map information to a point attribute.

• Copies information from a volume onto the point attributes of another piece of geometry, with optional remapping.

• Converts primitives for ODE and Bullet solvers.

• Computes lighting values within volume primitives

• Provides operations for moving knots within the parametric space of a NURBS curve or surface.

• Applies deformations such as bend, taper, squash/stretch, and twist.

• Deletes primitives, points, edges or breakpoints.

• Computes a 3D metamorphosis between shapes with the same topology.

• Computes a 3D metamorphosis between shapes with the same topology.

• The start of a looping block.

• The start of a compile block.

• The end/output of a looping block.

• The end/output of a compile block.

• Supports Bone Deform by assigning capture weights to bones.

• Supports Deform by assigning capture weights to points based on biharmonic functions on tetrahedral meshes.

• Supports Bone Capture Biharmonic by creating lines from bones with suitable attributes.

• Supports Bone Deform by assigning capture weights to points based on distance to bones.

• Uses capture attributes created from bones to deform geometry according to their movement.

• Creates default geometry for Bone objects.

• Combines two polygonal objects with boolean operators, or finds the intersection lines between two polygonal objects.

• Fractures the input geometry using cutting surfaces.

• Creates a bounding box, sphere, or rectangle for the input geometry.

• Creates a cube or six-sided rectangular box.

• Deforms the points in the first input using one or more magnets from the second input.

• Records and caches its input geometry for faster playback.

• Closes open areas with flat or rounded coverings.

• Converts array attributes into a single index-pair capture attribute.

• Converts a single index-pair capture attribute into per-point and detail array attributes.

• Adjusts capture regions and capture weights.

• Lets you paint capture attributes directly onto geometry.

• Copies capture attributes from one half of a symmetric model to the other.

• Overrides the capture weights on individual points.

• Supports Capture and Deform operation by creating a volume within which points are captured to a bone.

• Slices, cuts or extracts points or cross-sections from a primitive.

• Reads sample data from a chop and converts it into point positions and point attributes.

• Creates open or closed arcs, circles and ellipses.

• Lets you deform NURBS faces and NURBS surfaces by pulling points that lie directly on them.

• Helps clean up dirty models.

• Removes or groups geometry on one side of a plane, or creases geometry along a plane.

• Captures low-res simulated cloth.

• Deforms geometry captured by the Cloth Capture SOP.

• Creates a volume representation of source geometry.

• Fills a volume with a diffuse light.

• Applies a cloud like noise to a Fog volume.

• Low-level machinery to cluster points based on their positions (or any vector attribute).

• Higher-level node to cluster points based on their positions (or any vector attribute).

• Creates geometry and VDB volumes for use with DOPs collisions.

• Adds color attributes to geometry.

• Adjust surface point normals by painting.

• Creates lines between nearby pieces.

• Creates an attribute with a unique value for each set of connected primitives or points.

• Creates simple geometry for use as control shapes.

• Converts geometry from one geometry type to another.

• Converts a 2D height field to a 3D VDB volume, polygon surface, or polygon soup surface.

• Converts the input geometry into line segments.

• Polygonizes metaball geometry.

• Generates the oriented surface of a tetrahedron mesh.

• Converts sparse volumes.

• Converts a Point Cloud into a VDB Points Primitive, or vice versa.

• Converts the iso-surface of a volume into a polygonal surface.

• Decomposes the input geometry into approximate convex segments.

• Creates multiple copies of the input geometry, or copies the geometry onto the points of the second input.

• Copies geometry and applies transformations to the copies.

• Copies the geometry in the first input onto the points of the second input.

• Manually adds or removes a creaseweight attribute to/from polygon edges, for use with the Subdivide SOP.

• Deforms and animates a piece of geometry across a surface.

• Populates a crowd of agent primitives.

• Creates crowd agents to be used with the crowd solver.

• Creates polygonal, NURBS, or Bezier curves.

• Deforms a spline surface by reshaping a curve on the surface.

• Finds the intersections (or points of minimum distance) between two or more curves or faces.

• Imports fields from DOP simulations, saves them to disk, and loads them back again.

• Imports scalar and vector fields from a DOP simulation.

• Imports option and record data from DOP simulations into points with point attributes.

• Generates point emission sources for debris from separating fractured rigid body objects.

• Runs a VEX snippet to deform geometry.

• Deletes input geometry by group, entity number, bounding volume, primitive/point/edge normals, and/or degeneracy.

• Smooths out (or "relaxes") point deformations.

• Attempts to prevent collisions when deforming geometry.

• Deletes edges from the input polygonal geometry merging polygons with shared edges.

• Deletes points, primitives, and edges from the input geometry and repairs any holes left behind.

• Divides, smooths, and triangulates polygons.

• Imports and transforms geometry based on information extracted from a DOP simulation.

• Creates a curve based on user input in the viewport.

• Culls the input geometry according to the specifications of the For Each SOP.

• Collapses edges and faces to their centerpoints.

• Sharpens edges by uniquing their points and recomputing point normals.

• Inserts points on the edges of polygons and optionally connects them.

• Flips the direction of polygon edges.

• Cuts geometry along edges using guiding curves.

• Copies and optionally modifies attribute values along edges networks and curves.

• Edits points, edges, or faces interactively.

• Closes, opens, or clamps end points.

• Sets an attribute on selected points or primitives to sequential numbers.

• Generates a message, warning, or error, which can show up on a parent asset.

• Pushes geometry out from the center to create an exploded view.

• Pushes geometry out from the center to create an exploded view.

• Computes the centroid of each piece of the geometry.

• Computes the best-fit transform between two pieces of geometry.

• Extrudes geometry along a normal.

• Extrudes surface geometry into a volume.

• Creates a surface or density VDB for sourcing FLIP simulations.

• Controls the smoothness of faceting of a surface.

• Adds smooth distance attributes to geometry.

• Evolves polygonal curves as vortex filaments.

• Reads, writes, or caches geometry on disk.

• Writes and reads geometry sequences to disk.

• Reads and collates data from disk.

• Creates smooth bridging geometry between two curves or surfaces.

• Finds the shortest paths from start points to end points, following the edges of a surface.

• Fits a spline curve to points, or a spline surface to a mesh of points.

• Compresses the output of fluid simulations to decrease size on disk

• Creates 3D text from Type 1, TrueType and OpenType fonts.

• Uses a metaball to attract or repel points or springs.

• Creates jagged mountain-like divisions of the input geometry.

• Creates a set of hair-like curves across a surface.

• Merges points.

• Merges or splits (uniques) points.

• Adds strength to a glue constraint network according to cluster values.

• Generates particles to be used as sources in a particle-based grain simulation.

• Assigns a unique integer attribute to non-touching components.

• Creates planar geometry.

• Blends the guides and skin of two grooms.

• Fetches groom data from grooming objects.

• Packs the components of a groom into a set of named Packed Primitives for the purpose of writing it to disk.

• Switches between all components of two groom streams.

• Unpacks the components of a groom from a packed groom.

• Generates groups of points, primitives, edges, or vertices according to various criteria.

• Combines point groups, primitive groups, or edge groups according to boolean operations.

• Copies groups between two pieces of geometry, based on point/primitive numbers.

• Deletes groups of points, primitives, edges, or vertices according to patterns.

• Runs VEX expressions to modify group membership.

• Sets group membership interactively by painting.

• Converts point, primitive, edge, or vertex groups into point, primitive, edge, or vertex groups.

• Groups points and primitives by ranges.

• Renames groups according to patterns.

• Transfers groups between two pieces of geometry, based on proximity.

• Advects guide points through a velocity volume.

• Resolves collisions of guide curves with VDB signed distance fields.

• Deforms geometry with an animated skin and optionally guide curves.

• Allows intuitive manipulation of guide curves in the viewport.

• Creates standard primitive groups used by grooming tools.

• Quickly give hair guides some initial direction.

• Creates masking attributes for other grooming operations.

• Creates and prepares parting lines for use with hair generation.

• Looks up skin geometry attributes under the root point of guide curves.

• Constructs a coherent tangent space along a curve.

• Transfer hair guides between geometries.

• Converts dense hair curves to a polygon card, keeping the style and shape of the groom.

• Clumps guide curves together.

• Generates hair on a surface or from points.

• Generates a velocity field based on stroke primitives.

• Generates an initial heightfield volume for use with terrain tools.

• Blurs a terrain height field or mask.

• Limits height values to a certain minimum and/or maximum.

• Creates a copy of a height field or mask.

• Extracts a square of a certain width/length from a larger height volume, or resizes/moves the boundaries of the height field.

• Creates a cutout on a terrain based on geometry.

• Displaces a height field by another field.

• Advects the input volume through a noise pattern to break up hard edges and add variety.

• Lets you draw shapes to create a mask for height field tools.

• Calculates thermal and hydraulic erosion over time (frames) to create more realistic terrain.

• Calculates thermal and hydraulic erosion over time (frames) to create more realistic terrain.

• Simulates the erosion from one heightfield sliding over another for a short time.

• Distributes water along a heightfield. Offers controls for adjusting the intensity, variability, and location of rainfall.

• Calculates the effect of thermal erosion on terrain for a short time.

• Imports a 2D image map from a file or compositing node into a height field or mask.

• Generates flow and flow direction layers according to the input height layer.

• Copies another layer over the mask layer, and optionally flattens the height field.

• Composites together two height fields.

• Sets all values in a heightfield layer to a fixed value.

• Sets the border voxel policy on a height field volume.

• Creates a mask based on different features of the height layer.

• Creates a mask based some other geometry.

• Creates a mask where the input terrain is hollow/depressed, for example riverbeds and valleys.

• Adds vertical noise to a height field, creating peaks and valleys.

• Exports height and/or mask layers to disk as an image.

• Lets you paint values into a height or mask field using strokes.

• Patches features from one heightfield to another.

• Adds displacement in the form of a ramps, steps, stripes, Voronoi cells, or other patterns.

• Projects 3D geometry into a height field.

• Applies a material that lets you plug in textures for different layers.

• Remaps the values in a height field or mask layer.

• Changes the resolution of a height field.

• Scatters points across the surface of a height field.

• Scatters points across the surface of a height field.

• Simulates loose material sliding down inclines and piling at the bottom.

• Creates stepped plains from slopes in the terrain.

• Stitches height field tiles back together.

• Splits a height field volume into rows and columns.

• Height field specific scales and offsets.

• Visualizes elevations using a custom ramp material, and mask layers using tint colors.

• Makes holes in surfaces.

• Deforms the points in the first input to make room for the inflation tool.

• Instances Geometry on Points.

• Creates points with attributes at intersections between a triangle and/or curve mesh with itself, or with an optional second set of triangles and/or curves.

• Composes triangle surfaces and curves together into a single connected mesh.

• Processes its inputs using the operation of a referenced compiled block.

• Builds an offset surface from geometry.

• Generates an isometric surface from an implicit function.

• The Join op connects a sequence of faces or surfaces into a single primitive that inherits their attributes.

• Divides, deletes, or groups geometry based on an interactively drawn line.

• Creates fractal geometry from the recursive application of simple rules.

• Deforms geometry based on how you reshape control geometry.

• Reads a lidar file and imports a point cloud from its data.

• Creates polygon or NURBS lines from a position, direction, and distance.

• Animates points using an MDD file.

• Deforms geometry by using another piece of geometry to attract or repel points.

• Aligns the input geometry to a specific axis.

• Resizes and recenters the geometry according to reference geometry.

• Reorders the primitive and point numbers of the input geometry to match some reference geometry.

• Assigns one or more materials to geometry.

• Measures area, volume, or curvature of individual elements or larger pieces of a geometry and puts the results in attributes.

• Measures volume, area, and perimeter of polygons and puts the results in attributes.

• Merges geometry from its inputs.

• Defines groupings of metaballs so that separate groupings are treated as separate surfaces when merged.

• Creates metaballs and meta-superquadric surfaces.

• Duplicates and mirrors geometry across a mirror plane.

• Displaces points along their normals based on fractal noise.

• Displaces points along their normals based on fractal noise.

• Supports Muscle Deform by assigning capture weights to points based on distance away from given primitives

• Deforms a surface mesh representing skin to envelop or drape over geometry representing muscles

• Creates a "naming" attribute on points or primitives allowing you to refer to them easily, similar to groups.

• Computes surface normal attribute.

• Does nothing.

• Merges geometry from multiple sources and allows you to define the manner in which they are grouped together and transformed.

• Assists the creation of a Muscle or Muscle Rig by allowing you to draw a stroke on a projection surface.

• Deforms input geometry based on ocean "spectrum" volumes.

• Deforms input geometry based on ocean "spectrum" volumes.

• Generates particle-based foam

• Generates particles and volumes from ocean "spectrum" volumes for use in simulations

• Generates particles and volumes from ocean "spectrum" volumes for use in simulations

• Generates volumes containing information for simulating ocean waves.

• Instances individual waveforms onto input points and generated points.

• Executes an OpenCL kernel on geometry.

• Marks the output of a sub-network.

• Packs geometry into an embedded primitive.

• Packs points into a tiled grid of packed primitives.

• Editing Packed Disk Primitives.

• Editing Packed Primitives.

• Lets you paint color or other attributes on geometry.

• Creates a color volume based on drawn curve

• Creates a fog volume based on drawn curve

• Creates an SDF volume based on drawn curve

• Generates a surface around the particles from a particle fluid simulation.

• Creates a set of regular points filling a tank.

• Places points and primitives into groups based on a user-supplied rule.

• Moves primitives, points, edges or breakpoints along their normals.

• Creates a planar polygonal patch.

• Fills in a 2d curve network with triangles.

• Deforms flat geometry into a pleat.

• Creates platonic solids of different types.

• Manually adds or edits point attributes.

• Constructs an iso surface from its input points.

• Deforms geometry on an arbitrary connected point mesh.

• Creates new points, optionally based on point positions in the input geometry.

• Jitters points in random directions.

• Moves points with overlapping radii away from each other, optionally on a surface.

• Generates a cloud of points around the input points.

• Computes and manipulates velocities for points of a geometry.

• Creates set of regular points filling a volume.

• Creates flat or tube-shaped polygon surfaces between source and destination edge loops, with controls for the shape of the bridge.

• Creates offset polygonal geometry for planar polygonal graphs.

• Extrudes polygonal faces and edges.

• Creates straight, rounded, or custom fillets along edges and corners.

• Bevels points and edges.

• Breaks curves where an attribute crosses a threshold.

• Helps repair invalid polygonal geometry, such as for cloth simulation.

• Extrudes polygonal faces and edges.

• Fills holes with polygonal patches.

• Creates coordinate frame attributes for points and vertices.

• Creates new polygons using existing points.

• Creates a smooth polygonal patch from primitives.

• Cleans up topology of polygon curves.

• Reduces the number of polygons in a model while retaining its shape. This node preserves features, attributes, textures, and quads during reduction.

• Combines polygons into a single primitive that can be more efficient for many polygons

• The PolySpline SOP fits a spline curve to a polygon or hull and outputs a polygonal approximation of that spline.

• Divides an existing polygon into multiple new polygons.

• Divides an existing polygon into multiple new polygons.

• Stitches polygonal surfaces together, attempting to remove cracks.

• Constructs polygonal tubes around polylines, creating renderable geometry with smooth bends and intersections.

• Interpolates between a set of pose-shapes based on the value of a set of drivers.

• Combine result of Pose-Space Deform with rest geometry.

• Packs geometry edits for pose-space deformation.

• Creates common attributes used by the Pose-Space Edit SOP.

• Edits primitive, primitive attributes, and profile curves.

• Takes a primitive attribute and splits any points whose primitives differ by more than a specified tolerance at that attribute.

• Extracts or manipulates profile curves.

• Creates profile curves on surfaces.

• Creates points for sourcing pyro and smoke simulations.

• Runs a Python snippet to modify the incoming geometry.

• Combines fractured pieces or constraints into larger clusters.

• Creates attributes describing rigid body constraints.

• Creates rigid body constraint geometry from curves drawn in the viewport.

• Creates rigid body constraint geometry from interactively drawn lines in the viewport.

• Creates rigid body constraint geometry from a set of rules and conditions.

• Creates additional detail on the interior surfaces of fractured geometry.

• Fractures the input geometry based on a material type.

• Fractures the input geometry based on a material type.

• Packs RBD geometry, constraints, and proxy geometry into a single geometry.

• Paints values onto geometry or constraints using strokes.

• Unpacks an RBD setup into three outputs.

• Attaches RenderMan shaders to groups of faces.

• Generates surfaces by stretching cross-sections between two guide rails.

• Projects one surface onto another.

• Increases the number of points/CVs in a curve or surface without changing its shape.

• Scatters new guides, interpolating the properties of existing guides.

• Recreates the shape of the input surface using "high-quality" (nearly equilateral) triangles.

• Repacks geometry as an embedded primitive.

• Resamples one or more curves or surfaces into even length segments.

• Sets the alignment of solid textures to the geometry so the texture stays put on the surface as it deforms.

• Retimes the time-dependent input geometry.

• Reverses or cycles the vertex order of faces.

• Revolves a curve around a center axis to sweep out a surface.

• Rewires vertices to different points specified by an attribute.

• Generates ripples by displacing points along the up direction specified.

• Scatters new points randomly across a surface or through a volume.

• Runs scripts when cooked.

• Lets you interactively reshape a surface by brushing.

• Morphs though a sequence of 3D shapes, interpolating geometry and attributes.

• Sequence Blend lets you do 3D Metamorphosis between shapes and Interpolate point position, colors…

• Computes the post-deform or pre-deform difference of two geometries with similar topologies.

• Computes the convex hull of the input geometry and moves its polygons inwards along their normals.

• Takes the convex hull of input geometry and moves its polygons inwards along their normals.

• Builds a skin surface between any number of shape curves.

• Creates a sky filled with volumentric clouds

• Smooths out (or "relaxes") polygons, meshes and curves without increasing the number of points.

• Smooths out (or "relaxes") polygons, meshes and curves without increasing the number of points.

• Moves the selected point along its normal, with smooth rolloff to surrounding points.

• Moves the selected point, with smooth rolloff to surrounding points.

• Creates a tetrahedral mesh that conforms to a connected mesh as much as possible.

• Creates a simple tetrahedral mesh that covers a connected mesh.

• Creates a partition of a tetrahedral mesh that can be used for finite-element fracturing.

• Allows running a SOP network iteratively over some input geometry, with the output of the network from the previous frame serving as the input for the network at the current frame.

• Reorders points and primitives in different ways, including randomly.

• Creates a sphere or ovoid surface.

• Splits primitives or points into two streams.

• Spray paints random points onto a surface.

• A SOP node that sets the sprite display for points.

• Insets points on polygonal faces.

• Caches the input geometry in the node on command, and then uses it as the node’s output.

• Stretches two curves or surfaces to cover a smooth area.

• Low level tool for building interactive assets.

• Subdivides polygons into smoother, higher-resolution polygons.

• The Subnet op is essentially a way of creating a macro to represent a collection of ops as a single op in the Network Editor.

• Trims or creates profile curves along the intersection lines between NURBS or bezier surfaces.

• Creates a surface by sweeping cross-sections along a backbone curve.

• Switches between network branches based on an expression or keyframe animation.

• Sends input geometry to a TOP subnet and retrieves the output geometry.

• Reads a CSV file creating point per row.

• Creates a rock creature, which can be used as test geometry.

• Creates a pig head, which can be used as test geometry..

• Creates a rubber toy, which can be used as test geometry.

• Creates a shader ball, which can be used to test shaders.

• Creates a squab, which can be used as test geometry.

• Creates a soldier, which can be used as test geometry.

• Provides a simple crowd simulation for testing transitions between animation clips.

• Provides a simple Bullet simulation for testing the behavior of a ragdoll.

• Partitions a given tetrahedron mesh into groups of tets isolated by a given polygon mesh

• Performs variations of a Delaunay Tetrahedralization.

• Cooks the input at a different time.

• Sets attributes used by the Toon Color Shader and Toon Outline Shader.

• Lets you interactively draw a reduced quad mesh automatically snapped to existing geometry.

• Creates a torus (doughnut) shaped surface.

• Traces curves from an image file.

• Creates trails behind points.

• The Transform operation transforms the source geometry in "object space" using a transformation matrix.

• Transforms the input geometry relative to a specific axis.

• Transforms the input geometry by a point attribute.

• Transforms input geometry according to transformation attributes on template geometry.

• Creates a triangular Bezier surface.

• Refines triangular meshes using various metrics.

• Connects points to form well-shaped triangles.

• Trims away parts of a spline surface defined by a profile curve or untrims previous trims.

• Creates open or closed tubes, cones, or pyramids.

• Generates an edge group representing suggested seams for flattening a polygon model in UV space.

• Adjusts texture coordinates in the UV viewport by painting.

• Lets you interactively move UVs in the texture view.

• Creates flattened pieces in texture space from 3D geometry.

• Creates flattened pieces in texture space from 3D geometry.

• Merges UVs.

• Packs UV islands efficiently into a limited area.

• Relaxes UVs by pulling them out toward the edges of the texture area.

• Assigns UVs by projecting them onto the surface from a set direction.

• Applies an image file as a textured shader to a surface.

• Assigns texture UV coordinates to geometry for use in texture and bump mapping.

• Transforms UV texture coordinates on the source geometry.

• Transforms UV texture coordinates on the source geometry.

• Separates UVs into reasonably flat, non-overlapping groups.

• Processes geometry using an external program.

• Unpacks packed primitives.

• Unpacks points from packed primitives.

• Creates one or more empty/uniform VDB volume primitives.

• Activates voxel regions of a VDB for further processing.

• Expand or contract signed distance fields stored on VDB volume primitives.

• Moves VDBs in the input geometry along a VDB velocity field.

• Moves points in the input geometry along a VDB velocity field.

• Computes an analytic property of a VDB volumes, such as gradient or curvature.

• Clips VDB volume primitives using a bounding box or another VDB as a mask.

• Combines the values of two aligned VDB volumes in various ways.

• Tests VDBs for Bad Values and Repairs.

• Cuts level set VDB volume primitives into multiple pieces.

• Build an LOD Pyramid from a VDB.

• Blends between source and target SDF VDBs.

• Create a mask of the voxels in shadow from a camera for VDB primitives.

• Deletes points inside of VDB Points primitives.

• Manipulates the Internal Groups of a VDB Points Primitive.

• Computes the steady-state air flow around VDB obstacles.

• Removes divergence from a Vector VDB.

• Fixes signed distance fields stored in VDB volume primitives.

• Re-samples a VDB volume primitive into a new orientation and/or voxel size.

• Reshapes signed distance fields in VDB volume primitives.

• Splits SDF VDBs into connected components.

• Smooths out the values in a VDB volume primitive.

• Smooths out SDF values in a VDB volume primitive.

• Creates an SDF VDB based on the active set of another VDB.

• Merges three scalar VDB into one vector VDB.

• Splits a vector VDB primitive into three scalar VDB primitives.

• Replaces a VDB volume with geometry that visualizes its structure.

• Generates a signed distance field (SDF) VDB volume representing the surface of a set of particles from a particle fluid simulation.

• Converts point clouds and/or point attributes into VDB volume primitives.

• Converts polygonal surfaces and/or surface attributes into VDB volume primitives.

• Fills a VDB volume with adaptively-sized spheres.

• Configures geometry for Vellum Grain constraints.

• Configure constraints on geometry for the Vellum solvers.

• Vellum solver setup to pre-roll fabric to drape over characters.

• Packs Vellum simulations, saves them to disk, and loads them back again.

• Packs Vellum geometry and constraints into a single geometry.

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

• Blends the current rest values of constraints with a rest state calculated from external geometry.

• Runs a dynamic Vellum simulation.

• Unpacks a Vellum simulation into two outputs.

• Verify that a bsdf conforms to the required interface.

• Manually adds or edits attributes on vertices (rather than on points).

• Takes a vertex attribute and splits any point whose vertices differ by more than a specified tolerance at that attribute.

• Shows/hides primitives in the 3D viewer and UV editor.

• Lets you attach visualizations to different nodes in a geometry network.

• Creates a volume primitive.

• Computes analytic properties of volumes.

• Computes a speed-defined travel time from source points to voxels.

• Blurs the voxels of a volume.

• Bounds voxel data.

• Cuts polygonal objects using a signed distance field volume.

• Re-compresses Volume Primitives.

• Convolves a volume by a 3×3×3 kernel.

• Compute the Fast Fourier Transform of volumes.

• Feathers the edges of volumes.

• Flattens many volumes into one volume.

• Combines the scalar fields of volume primitives.

• Translates the motion between two "image" volumes into displacement vectors.

• Fill in a region of a volume with features from another volume.

• Remaps a volume according to a ramp.

• Rasterizes into a volume.

• Samples point attributes into VDBs.

• Converts a curve into a volume.

• Converts fur or hair to a volume for rendering.

• Converts a point cloud into a volume.

• Converts a point cloud into a volume.

• Reduces the values of a volume into a single number.

• Resamples the voxels of a volume to a new resolution.

• Resizes the bounds of a volume without changing voxels.

• Builds a Signed Distance Field from an isocontour of a volume.

• Extracts 2d slices from volumes.

• Splices overlapping volume primitives together.

• Stamps volumes instanced on points into a single target volume.

• Adaptively surfaces a volume hierarchy with a regular triangle mesh.

• Computes a trail of points through a velocity volume.

• Runs CVEX on a set of volume primitives.

• Computes a velocity volume.

• Generates a volume velocity field using curve tangents.

• Generates a velocity field within a surface geometry.

• Adjusts attributes for multi-volume visualization.

• Runs a VEX snippet to modify voxel values in a volume.

• Sets the voxels of a volume from point attributes.

• Fractures the input geometry by performing a Voronoi decomposition of space around the input cell points

• Fractures the input geometry by performing a Voronoi decomposition of space around the input cell points

• Given an object and points of impact on the object, this SOP generates a set of points that can be used as input to the Voronoi Fracture SOP to simulate fracturing the object from those impacts.

• Cuts the geometry into small pieces according to a set of cuts defined by polylines.

• Creates the point attributes needed to create a Vortex Force DOP.

• Generates volumes to be used as sources in a whitewater simulation.

• Generates emission particles and volumes to be used as sources in a Whitewater simulation.

• Computes generalized winding number of surface at query points.

• Morphs between curve shapes while maintaining curve length.

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

• Deforms geometry captured to a curve via the Wire Capture node.

• Transfers the shape of one curve to another.

• Constructs polygonal tubes around polylines, creating renderable geometry.

• Assigns channel paths and/or pickscripts to geometry.