GeoNodus — procedural geometry engine

Box, sphere, polysphere, torus and NURBS curve objects

PRIMITIVES

Scene objects and generators

An object-level scene (/obj) with several geometry objects, each holding its own SOP network.

Generators: Box, Sphere (polygon mesh and icosahedral polygon), Torus, Grid, Circle, and NURBS / Bezier curves; Add builds points and polygons by hand.
The full object Transform tab: transform and rotation order, pivot, uniform scale, pre-transform, Keep Position When Parenting, Child Compensation.
Object parenting and world transforms; the viewport shows points and curve hulls.

boxspheretorusgridcircleaddnull

Field of colored tori copied onto scattered points

TRANSFORM

Copy to Points

A torus is copied onto points scattered over a grid. Every copy picks up the random color of its target point, giving thousands of objects that update interactively.

Orients and scales copies by N, up, orient, pscale, scale, trans and transform.
Can copy, multiply, add or subtract attributes from the target, and copies target groups.
Copy and Transform makes N copies with incremental transforms; the Transform SOP moves, rotates and scales geometry or a group.

copytopointscopyxformxformgrid

TRANSFORM

Match Size

Scales and moves geometry so that its bounding box fits a target box: the second input, a given location and size, or the origin and unit size.

Scale per axis, uniformly by one axis, Best Fit, or so that the perimeter, area or volume match.
Justify each axis to the minimum, center or maximum, with an offset.
Stash the transform into a detail attribute and restore it later; vectors and normals are transformed by their type.

matchsize

$Torus deformed by fractal noise$

DEFORM

Mountain

Fractal noise pushes a torus's points along their normals and turns it into an organic shape.

A Unified Noise implementation: Perlin, Simplex, Worley, Alligator, Flow, Sparse and Sinusoid bases.
Fractals: Standard (fBm), Terrain and Hybrid Terrain, with octaves, lacunarity and roughness.
Fold, Complement, Gain/Bias, clipping, Lattice and Gradient Warp; time-dependent noise for animation.

mountain

DEFORM

Bend

A bend deformer applied to a torus inside a capture region, with random per-primitive colors.

Bend by angle or goal direction, plus Twist, Length Scale (with Preserve Volume), Taper and Squish, and a profile ramp.
Capture origin, direction, length and up vector; limit the deformation or deform in both directions.
Vectors, normals and quaternions are transformed through the deformation Jacobian.

bendxform

DEFORM

Path Deform

Lays geometry along curves: its forward axis follows each curve, with stretching, tapering and rolling along the way. Here a box follows a NURBS curve fitted through a few points, its width shaped by a Catmull-Rom scale ramp. Matches Houdini's Path Deform point for point.

Polylines, closed curves (geometry wraps around) and NURBS / Bezier curves; one copy of the geometry per curve, or pieces matched to curves by a piece attribute.
Start and end offsets in curve, geometry or world units; Extend, Clamp or Clip at the ends; uniform scale with Preserve Volume.
Taper and Rotate with ramps and curve attributes; rigid parts kept undeformed, with stretch softening and a mask.
Curve frames from Orient along Curve (up vector, point attributes, constant up, blended tangents); vectors, normals and quaternions follow the deformation.

pathdeform

Sphere with random point colors and geometry spreadsheet

ATTRIBUTES

Attribute Create & Attribute Randomize

Each point of a sphere gets a random color (Cd). The spreadsheet below the viewport reads positions and colors straight from the library.

Point, vertex, primitive and detail attributes: int, float and string, with sizes 1–4 and type info.
Paged, copy-on-write attribute storage shared between nodes; operations are limited to group members.
A HAPI-style attribute API: gnGetAttributeInfo, gnGetAttributeFloatData, …

attribcreateattribrandomize

ATTRIBUTES

Attribute Blur

Smooths point attributes (positions, colors, any float attribute) across the surface.

Laplacian, Volume Preserving (Taubin, no shrinking) or custom odd / even steps; uniform or edge-length weights.
Neighbours by connectivity or by proximity; pinned border points, a weight attribute and a group.
A second input can supply the reference geometry; the result can be blended with the original.

attribblur

GROUPS

Group Range & Group Create

Every second primitive of a box goes into group gr (Select 1 of 2); random colors are then applied to the group alone.

Ranges: start/end, relative, equal partitions, inversion, select N of M with offset.
Per-connected-piece ranges, collision groups and merge methods.
Group Create can filter by bounding region, normal, edge angle/length and random chance; point, primitive and edge groups are supported.

grouprangegroupcreate

Torus, sphere and box with a UV test texture, combined by a merge node

UV

UV Texture

A torus, a sphere and a box each get texture coordinates from their own UV Texture node and are combined into one geometry with Merge. The test texture shows how the UVs are laid out.

Projections: Orthographic, Polar, Cylindrical, Face, Rows & Columns and Modify Source; Uniform, Average and Arc Length spacing for curves.
UVs are stored on points or vertices (or chosen automatically), with scale, offset, rotation and Fix Boundary Seams.
Merge combines up to 10 inputs and unites their attributes, types and groups the way Houdini does.

texturemergetorusspherebox

TOPOLOGY

PolyExtrude

The faces in group gr are extruded with an inset, turning the flat stripes into raised ribs.

Extrudes individual elements or connected components; settings include distance, inset, twist, divisions and thickness/twist ramps.
Can extrude along a curve from the second input; also extrudes open curves into ribbons.
Front, back and side output groups; unwrapped UVs for the sides; vertex normals.

polyextrude

TOPOLOGY

PolyBevel

Every edge of a box is rounded with a 12-division fillet. Corner patches are generated and normals are recomputed afterwards.

Bevels edges and points; fillet shapes are Round, Chamfer, Crease, Solid and None.
Profiles come from a ramp or a curve; sampling can be uniform, adaptive or by control points.
Collision detection, sliding on ring edges and stop-loop limits.

polybevelnormal

TOPOLOGY

Curves

Polylines, NURBS and Bezier curves are first-class primitives: they are built, edited and read through a HAPI-style curve API (gnGetCurveInfo, gnGetCurveKnots, …).

Fit turns polylines into NURBS or Bezier curves: global or local interpolation, breakpoints, or approximation within a tolerance.
Resample splits curves into even segments by length or count, with subdivision curves and distance, tangent and curveu attributes.
Carve cuts out a piece of a curve by parameter or arc length; Join connects curves end to end with blending.
Orient along Curve builds frames along curves (tangent, up, twist, extra rotations) and writes N, up, orient or matrices for Copy to Points.

fitresamplecarvejoinorientalongcurve

TOPOLOGY

Fuse

Merges points that lie close to each other, or snaps them to targets.

Snap by distance (to the least or the closest target point), to points of a second input, to points given by an attribute, or to a grid.
Positions and attributes of merged points are combined by average, min, max, mode, median, first, last and more.
Repeated vertices, degenerate polygons and unused points are removed; affected normals can be recomputed.

fuse

BOOLEAN

Boolean

Boolean operations on polygon meshes, with attributes transferred to the result.

Union, Intersect, Subtract (A − B, B − A or both) and Shatter into pieces of A, B or both.
Point, vertex, primitive and detail attributes and groups are carried over from both inputs, and values are interpolated at the new points along the seam.
An open surface can be cut by a solid or used to split it (Treat As Surface); seam and piece output groups.

boolean

Torus clipped by a plane with filled caps

BOOLEAN

Clip with capping

A torus is cut by a plane and the openings are filled with caps. Only the caps (group filled) are recolored.

Keep above, below or both sides; set origin, direction, distance and snap tolerance.
Attributes are interpolated onto the new points; caps with holes are bridged the same way as in Houdini.
The Normal SOP recomputes point, vertex, primitive or detail normals with a cusp angle.

clipnormal

PARTICLES

Scatter

Thousands of points are spread evenly over a sphere's surface, and each one inherits the color of the surface beneath it.

Sets a total count, a density, or a density attribute; also scatters per primitive or in texture space.
Relax iterations push points apart for an even, blue-noise-like layout, using a parallel BVH.
Transfers attributes and groups from the source surface; writes sourceprim and sourceprimuv.

scatter

IO

File (OBJ)

The File SOP reads Wavefront OBJ files into the graph, so hand-made models can be combined with procedural geometry.

Polygons, polylines, texture coordinates, normals and vertex colors.
uv and N are stored on points or vertices the same way Houdini decides it.
A missing file can be an error or an empty geometry; paths are UTF-8 on every platform.

file

SUBNETWORK

SOP subnets

Parts of a network can be wrapped into a subnet that behaves like a single operator with its own inputs and outputs.

Four inputs, available inside through input nodes, and up to 11 outputs chosen by Output SOPs.
Subnets can be nested; an input nobody reads inside is not cooked, and editing a node that does not feed an output does not recook the subnet.
Null passes geometry through unchanged and is handy as a named reference point.

subnetoutputnull

SCENE

Channels and expressions

An animated castle scene with about 130 nodes. Its timing, tower count, wall radius and wind are read from the channels of the null object ctrl; the parameters highlighted in green there are driven by expressions.

Any parameter component can hold an expression with time variables ($T, $F, $FPS, …) and math functions.
ch() references read other parameters by absolute or relative path, and the paths are updated when a node is renamed.
Changing the time recooks only the nodes that depend on it; object transforms and parenting work as in Houdini.

nullgeoch()$T

SCENE

Spare parameters

Any node can get its own parameters on top of the built-in ones, just like spare parameters in Houdini. A typical use is a control null that collects the high-level controls of a whole scene, which other nodes then read through ch().

Integer, float and vector parameters, toggles, menus, strings and file paths, plus folders, labels and separators for layout.
Each parameter has a default value, a range, Disable When / Hide When conditions and an option to join with the next parameter.
Spare parameters work like built-in ones: they hold expressions, can be referenced with ch(), and are saved with the graph.
Renaming a spare parameter rewrites every ch() reference to it in all nodes.
The API is gnAddSpareParm, gnRenameSpareParm and gnRemoveSpareParm; the client's Edit Parameter Interface dialog is built on these calls.

spare parmsnullch()

Procedural geometry,
live at run time.

What GeoNodus is

API that mirrors HAPI

Run-time parametric modeling

Dynamic, animated scenes

Runs where your app runs

What already works

Scene objects and generators

Copy to Points

Match Size

Mountain

Bend

Path Deform

Attribute Create & Attribute Randomize

Attribute Blur

Group Range & Group Create

UV Texture

PolyExtrude

PolyBevel

Curves

Fuse

Boolean

Clip with capping

Scatter

File (OBJ)

SOP subnets

Channels and expressions

Spare parameters