Generate#

Primitives, curves, terrain and other nodes that create geometry from nothing.

24 nodes.

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Contents#

• Add (PCG) — Creates points from typed coordinates, connects points into polygons, or strips a mesh down to its points.
• Ballistic Path (PCG) — Fires a projectile from each point and outputs its trajectory as a polyline.
• Box (PCG) — Creates a box as polygons or as a lattice of points.
• Circle (PCG) — Creates a circle, ellipse or arc as a polygon or a curve.
• Cross Section Surface (PCG) — Builds a smooth Gordon surface through a net of section and guide curves.
• Cross Section Surface · Houdini (PCG) — Skins a surface through cross-section curves using their existing points, like Houdini's Cross Section Surface.
• Curve (PCG) — A curve drawn in the viewport, like Houdini's Curve SOP.
• Extract Silhouette (PCG) — Extracts the silhouette of a mesh as projected outlines or as a contour on the surface.
• Font (PCG) — Creates text geometry from a TrueType or OpenType font as outlines, faces or extruded solids.
• Grid (PCG) — Creates a flat grid of points, polygons or lines.
• IsoOffset (PCG) — Converts geometry to an offset isosurface, an SDF volume or a fog volume.
• IsoSurface (PCG) — Extracts a polygon surface or volume from an implicit function evaluated on a grid.
• L-System (PCG) — Grows a branching structure by rewriting a premise string with rules and drawing it with a 3D turtle.
• Line (PCG) — Creates a straight line with evenly spaced points.
• Platonic Solids (PCG) — Creates a Platonic solid or a soccer ball.
• PolyLoft (PCG) — Connects existing curves into a surface or lines using their own points.
• PolyWire (PCG) — Builds tubes along every edge of a curve network, with closed joints at branches.
• Revolve (PCG) — Spins a profile curve around an axis to create a surface of revolution.
• Skin (PCG) — Skins a surface across a set of cross-section curves.
• Sphere (PCG) — Creates a sphere as a latitude/longitude mesh or a subdivided icosahedron.
• Sweep (PCG) — Sweeps a cross section along backbone curves to make tubes, ribbons or custom profiles.
• Torus (PCG) — Creates a torus.
• Tube (PCG) — Creates a tube, cylinder or cone with optional end caps.
• Volume (PCG) — Creates a constant-value volume.

Nodes#

Add (PCG)#

PCG_Add · category PCG/generate · Houdini: Add (SOP), Point Generate (SOP)

Creates points from typed coordinates, connects points into polygons, or strips a mesh down to its points.

Covers the three jobs of Houdini's Add SOP, all of which change point/primitive membership rather than positions: creating points, wiring points into polygons or polylines, and discarding primitives while keeping the points.

Operations run in Houdini's order: Delete Geometry But Keep the Points, then append the new points, then build polygons, then the cleanup. New points are appended after the existing ones, so every polygon-building method can reference both input points and new points by number. With no input connected the node is a pure generator.

The panel differs from Houdini in one way: points and polygons are not multiparms. Points are typed into a multiline text box, one per line (x y z, separated by spaces, commas or semicolons; lines may contain # comments; two numbers imply z = 0, a fourth number is ignored). Polygons by pattern are also one per line. Point-number lists keep their order and repeats, because winding matters: 3 1 2 and 1 2 3 are different faces. Out-of-range point numbers raise an error rather than being skipped. Primitives with fewer than three corners are always created open.

Inputs

Outputs

Parameters

Points

Polygons › Polygons by Pattern

Polygons › Polygons by Group

Polygons › Polygons by Attribute

Polygons › Remove

Compared with Houdini

Points and polygons are entered as multiline text instead of multiparm blocks, because ComfyUI cannot add or remove widgets dynamically without breaking saved workflows.

Ballistic Path (PCG)#

PCG_BallisticPath · category PCG/generate · Houdini: Ballistic Path (SOP)

Fires a projectile from each point and outputs its trajectory as a polyline.

Each selected point becomes the start of a ballistic trajectory under constant gravity with optional linear air drag (an analytic solution, not a simulation). The result is one open polyline per point, sampled at a fixed number of points.

In the Free launch method the initial velocity comes from a vector point attribute and the path runs for the given life. The two Targeted methods take points from the second input as targets, paired with the launch points by point number, and solve for the initial velocity: either for a given flight time, or for a given launch elevation angle. Launch points whose target is missing or cannot be reached with that angle are skipped and counted in the report.

Optionally the path is cut where it falls below a ground height measured along gravity, or at its first hit on the collision geometry (found by ray casting the path segments and refining the hit within the segment). The output carries the source point attributes on every path point, plus time and v (velocity) on points and srcpoint on primitives. The report output counts paths, unreachable targets, ground hits and collision hits.

Inputs

Outputs

Parameters

General

Projectile Properties

Basic Collision

Compared with Houdini

The number of path points is set directly (Points per Path) instead of FPS times life. Air drag is linear and solved analytically.

Tips

• With collision connected, the path is cut at the first hit even when Ground is off.

Box (PCG)#

PCG_Box · category PCG/generate · Houdini: Box (SOP)

Creates a box as polygons or as a lattice of points.

Generates an axis-aligned box of the given size, then applies the rotation and uniform scale around its center. With Axis Divisions of 2 on each axis every face is one quad, as in Houdini; larger values add points along that axis.

Outputs

Parameters

Circle (PCG)#

PCG_Circle · category PCG/generate · Houdini: Circle (SOP)

Creates a circle, ellipse or arc as a polygon or a curve.

Generates a circle with two radii (so ellipses are possible) lying in the chosen plane, then applies an optional Euler rotation, the uniform scale and the center offset. Circles are often used as Sweep cross sections or PolyExtrude inputs, which is why the output winding can be reversed: with the wrong direction all normals point inward.

The arc options turn the circle into an arc: an open arc, a closed arc (arc plus a chord), or a sliced arc (arc plus two radii back to the center, a pie slice).

Outputs

Parameters

Rotate

Spline

Arc

Cross Section Surface (PCG)#

PCG_CrossSectionSurface · category PCG/generate

Builds a smooth Gordon surface through a net of section and guide curves.

Weaves the sections curves and the optional guides curves into a net and builds a Gordon surface: the two curve families are each lofted, the results are added, and the tensor-product interpolation at the intersections is subtracted. The surface passes exactly through every curve in the net. Without guides it is simply a loft along the sections.

If the curves are closed the surface is closed in that direction. The output is a quad mesh with a point uv attribute.

Inputs

Outputs

Parameters

Compared with Houdini

Different from the Houdini node: this one resamples and interpolates a Gordon surface from two curve families. The node 'Cross Section Surface · Houdini' follows Houdini's behaviour of connecting existing points.

Cross Section Surface · Houdini (PCG)#

PCG_CrossSectionSurfaceHou · category PCG/generate · Houdini: Cross Section Surface (SOP)

Skins a surface through cross-section curves using their existing points, like Houdini's Cross Section Surface.

Follows Houdini's behaviour: like a Sweep with only cross sections. Each cross-section curve is one row of the grid and its c-th point is column c. The surface is built from the existing points of the curves, with no resampling or interpolation, so all cross sections must have the same number of points (otherwise the node errors). If the cross sections are closed the result is a tube; with Close Implicit Backbone Curve the last section also connects back to the first.

Surface Type chooses what is built over the grid: points, rows, columns, both, quads or several triangulations. End caps can be a single polygon, a grid (hemisphere, cone or dish shaped via Scale and Roundness) or, for closed backbones, a side polygon. Single Polygon and Grid caps need closed cross sections and an open backbone; Side Single Polygon needs a closed backbone and open cross sections.

UVs can be computed with the same switches as Houdini (length weighting, normalization, seamless wrapping, flipping, scaling); on polygon output they are stored on vertices. Row/column numbers and the cross-section number can be written to attributes whose names you set; an empty name writes nothing.

Inputs

Outputs

Parameters

Cross Section

Surface

UV Coordinates

Attributes

Compared with Houdini

Matches the Houdini node. The separate node Cross Section Surface (PCG) is a different algorithm (Gordon surface with resampling and interpolation).

Curve (PCG)#

PCG_Curve · category PCG/generate · Houdini: Curve (SOP)

A curve drawn in the viewport, like Houdini's Curve SOP.

Select the node and draw in the viewport: click to add points, drag points to move them, Ctrl + click a segment to insert a point, Delete over a point to remove it, and click the first point to close the curve. Points land on the displayed geometry when the click hits it, otherwise on a construction plane (see Drawing curves).

The points are stored as text in Points, one x, y, z per line, so the curve is saved with the workflow and can be edited by hand. Houdini's coordinate style x,y,z x,y,z on one line and ; as a separator are also accepted; missing components are 0.

With fewer than two points the output is just the point (or nothing). Close Curve needs at least three points.

Outputs

Parameters

Compared with Houdini

Covers Curve SOP's drawing, moving, inserting, deleting and closing, with Polygon, NURBS and Bezier primitive types. Tangent handles, per-point weights, the Bezier sub-modes (corner / smooth) and editing several curves in one node are not implemented. The points are kept as text in a parameter, like the old Curve SOP's Coordinates.

Extract Silhouette (PCG)#

PCG_ExtractSilhouette · category PCG/generate · Houdini: Extract Silhouette (SOP)

Extracts the silhouette of a mesh as projected outlines or as a contour on the surface.

Projected Outline projects the geometry along Direction onto the plane through Origin and computes the exact boundary of the projected area (candidate silhouette edges are intersected and clipped, and segments are kept based on coverage on both sides). The result is closed polylines, with outer loops counter-clockwise and holes clockwise, carrying the primitive attributes hole and area.

Contour on Mesh finds the boundary of the front-facing region on the mesh itself and leaves it in 3D.

Inputs

Outputs

Parameters

Font (PCG)#

PCG_Font · category PCG/generate · Houdini: Font (SOP)

Creates text geometry from a TrueType or OpenType font as outlines, faces or extruded solids.

Reads vector glyph outlines from a ttf, otf or ttc font file and builds the text in the XY plane facing +Z. Outline gives closed contours (with a hole primitive attribute), Faces fills them with a constrained Delaunay triangulation that keeps holes, and Extruded adds a back face and side walls to make a watertight solid. Primitives carry char, char_index and line attributes.

The Font field accepts a path, a file name (e.g. arial, msyh) or a family name; empty uses arial or DejaVuSans. Characters missing from the main font are looked up in the fallback fonts in order. Size is the em height.

Outputs

Parameters

Grid (PCG)#

PCG_Grid · category PCG/generate · Houdini: Grid (SOP)

Creates a flat grid of points, polygons or lines.

Generates a rectangular grid in the chosen plane, then rotates and translates it. Rows and Columns count points, not cells, as in Houdini, so 21 x 21 gives 20 x 20 quads. Connectivity selects between quads, two triangle layouts, lines along rows and/or columns, or points only.

Outputs

Parameters

IsoOffset (PCG)#

PCG_IsoOffset · category PCG/generate · Houdini: IsoOffset (SOP)

Converts geometry to an offset isosurface, an SDF volume or a fog volume.

Samples the distance to the input geometry on a grid and outputs the isosurface at the given offset, or the field as a volume. Ray Intersect computes an exact signed distance (sign from pseudo-normals and flood fill, not rays); Minimum gives an unsigned distance; the other modes use point clouds or implicit boxes and spheres.

The grid is defined by the sampling options and the bounds, which are the bounding box of the input, the bounding box of the optional bound input, or user values. Note that division counts are grid points; in Houdini they are voxels.

Inputs

Outputs

Parameters

Compared with Houdini

Division counts are numbers of grid points rather than voxels. The Convert node's volume SDF and fog modes are unchanged and separate.

IsoSurface (PCG)#

PCG_IsoSurface · category PCG/generate · Houdini: IsoSurface (SOP)

Extracts a polygon surface or volume from an implicit function evaluated on a grid.

Evaluates the implicit function (wrangle syntax: @P, @P.x; $X $Y $Z are also accepted) at the grid points of the bounding box and extracts the surface where the function equals the Iso Value, using surface nets (quads, positive outside and negative inside). Project to Isosurface then refines each vertex onto the true isosurface with Newton iterations along the numerical gradient, and Compute Normals writes N from the gradient. The volume output outputs the sampled field directly.

Outputs

Parameters

L-System (PCG)#

PCG_LSystem · category PCG/generate · Houdini: L-System (SOP)

Grows a branching structure by rewriting a premise string with rules and drawing it with a 3D turtle.

The premise is rewritten for the given number of generations using the rules, then the resulting string is interpreted by a 3D turtle to produce lines. Rules are one per line, e.g. F=F[+F]F[-F]F. Writing several rules for the same character and prefixing each with a weight in parentheses makes them stochastic.

Turtle symbols: F draws a line, f moves without drawing, + - turn left/right, & ^ pitch down/up, \ / roll, | turns around, [ ] open and close a branch, ! makes the line thinner, " makes it shorter, and J K L M place leaf points. Leaf points are added to the point group leaves and carry N, up, orient and name.

Points carry width, generation (the generation in which the segment appeared) and depth. If the rewritten string grows beyond Max Symbols the node raises an error instead of truncating.

Outputs

Parameters

Geometry

Rules

Line (PCG)#

PCG_Line · category PCG/generate · Houdini: Line (SOP)

Creates a straight line with evenly spaced points.

Generates a polyline starting at Origin, running along Direction for the given Length, with the given number of points.

Outputs

Parameters

Platonic Solids (PCG)#

PCG_PlatonicSolids · category PCG/generate · Houdini: Platonic Solids (SOP)

Creates a Platonic solid or a soccer ball.

Generates a tetrahedron, cube, octahedron, dodecahedron, icosahedron or soccer ball (truncated icosahedron) with outward-facing faces and shared points (watertight). Radius is the circumscribed sphere radius. The primitive attribute sides stores the number of edges of each face (on the soccer ball, 5 for the black patches and 6 for the white ones). The octahedron and dodecahedron are built as duals, and the soccer ball by truncating the icosahedron at one third of each edge.

Outputs

Parameters

PolyLoft (PCG)#

PCG_PolyLoft · category PCG/generate · Houdini: PolyLoft (SOP)

Connects existing curves into a surface or lines using their own points.

No points are created. Faces builds surfaces between adjacent curves: quads when the curves have the same number of points, otherwise triangles zippered by arc length. Cross Lines connects the i-th point of each curve into lines across the curves, and Grid Lines produces those lines plus the original curves. Wrap Last to First also connects the last curve to the first.

Inputs

Outputs

Parameters

PolyWire (PCG)#

PCG_PolyWire · category PCG/generate · Houdini: PolyWire (SOP), Wireframe (SOP)

Builds tubes along every edge of a curve network, with closed joints at branches.

Puts a tube on every edge of the input's polylines and polygons. Unlike Sweep, which works one curve at a time, PolyWire treats the edges as a network: shared points are joined, so branching structures (trees, L-systems, wire frames, road graphs) come out as one connected set of tubes.

The network is cut into chains at ends and junctions; each chain gets a tube with rotation-minimising frames. Junctions and sharp bends get a sphere of the wire radius so branches have no gaps, and open ends get round or flat caps. The radius can come from point attributes (width as a diameter, pscale as a radius).

Inputs

Outputs

Parameters

Revolve (PCG)#

PCG_Revolve · category PCG/generate · Houdini: Revolve (SOP)

Spins a profile curve around an axis to create a surface of revolution.

A full 360 degree revolution does not duplicate the first column of points. Profile points lying on the axis are placed only once, so a half circle becomes a sphere with a single point at each pole and triangles there, with no zero-area faces. A closed profile gives a torus-like surface. For partial revolutions, End Caps closes the profile at the ends. A profile drawn from bottom to top on the positive side of the axis produces outward normals; use Reverse Normals otherwise.

When a UV attribute name is given, uv is written with u as the fraction of the angle swept and v as the fraction of the profile arc length.

Inputs

Outputs

Parameters

Skin (PCG)#

PCG_Skin · category PCG/generate · Houdini: Skin (SOP)

Skins a surface across a set of cross-section curves.

Cross sections are sorted by primitive number and a strip of faces is built between each adjacent pair; if the sections themselves are closed the surface also closes around in the U direction. Output can be polygons or a NURBS surface.

Unlike Houdini, which errors when the sections have different point counts, Auto Resample (on by default) aligns them automatically, since sections often come from different sources. Turn it off for Houdini's strict behaviour.

Inputs

Outputs

Parameters

Alignment

NURBS

Grouping

Compared with Houdini

Auto Resample is an addition: Houdini requires all sections to have the same number of points.

Sphere (PCG)#

PCG_Sphere · category PCG/generate · Houdini: Sphere (SOP)

Creates a sphere as a latitude/longitude mesh or a subdivided icosahedron.

Polygon Mesh is a UV sphere with Rows by Columns points and a single point at each pole. Polygon is a subdivided icosahedron, whose triangles are uniform in size and which has no poles; each edge is split into Frequency segments for 20 * f^2 triangles. Radii can differ per axis for ellipsoids.

Outputs

Parameters

Sweep (PCG)#

PCG_Sweep · category PCG/generate · Houdini: Sweep (SOP)

Sweeps a cross section along backbone curves to make tubes, ribbons or custom profiles.

Each backbone curve gets a frame using rotation-minimizing frames, so the section does not twist at bends. The cross section's plane comes from its own principal axis, so sections from Circle, Carve and other nodes work whatever plane they were drawn in. Sections are either built in (round tube, square tube, ribbon) or taken from the second input.

At turns the section is stretched by 1/cos(half turn angle) so the tube keeps its apparent thickness; Max Stretch limits this at sharp corners. Scale can vary from start to end of the curve and can follow the point pscale; rotation options add roll and twisting. Output can be faces, lines (rows or columns) or points. Rows, columns and points have no end caps.

Inputs

Outputs

Parameters

Surface

Surface › End Caps

Scale › Scale

Rotation › Rotation

Cross Sections › Cross Section

Cross Sections › Turns

UVs and Attributes › UV

Compared with Houdini

Also covers the uses of PolyWire and Wireframe (round-tube sweep of curves).

Tips

• A circle created with the Circle node makes a good second-input cross section; use Reverse Cross Sections if the faces point inward.

Torus (PCG)#

PCG_Torus · category PCG/generate · Houdini: Torus (SOP)

Creates a torus.

Rows is the number of segments around the cross section and Columns the number of segments around the main circle. Both directions are periodic, so no duplicate end points are created (a duplicated ring would produce zero-area quads and undefined normals at the seam). This differs from Grid and Tube, where Rows/Columns count points rather than segments. The torus comes with periodic uv.

Outputs

Parameters

Center

Tube (PCG)#

PCG_Tube · category PCG/generate · Houdini: Tube (SOP)

Creates a tube, cylinder or cone with optional end caps.

A tube along the chosen axis with separate bottom and top radii (a cone when one is zero). The radius scale multiplies both. Rows and Columns count points: rows along the height and columns around the circumference.

Outputs

Parameters

Volume (PCG)#

PCG_Volume · category PCG/generate · Houdini: Volume (SOP)

Creates a constant-value volume.

Generates a volume sampled on a grid whose first and last grid points sit on the corners of the box. If the optional bound input is connected, its bounding box (expanded by Bounds Padding) defines the extent instead of Center and Size. A positive Voxel Size computes the resolution as extent divided by voxel size (voxels are cubes); otherwise Resolution is used. Fog Volume marks the field as a density (positive inside); when off it is an SDF.

Inputs

Outputs

Parameters