Andrei Mikhalenka

Hi everyone,

I’ve been doing a lot of curve-heavy work in Houdini 21 and wanted to propose a couple of quality-of-life improvements for the Curve 2.0 / curve editing tools. The idea is to make drawing and editing curves feel closer to modern spline modeling workflows, while still staying 100% procedural.

1. Shift-drag to duplicate curve / segment “in place”

Right now, if I want to duplicate a curve or part of a curve inside a single SOP, I usually have to:

select the curve / points

Ctrl+C / Ctrl+V and it plase it under the mouse point that not really handy, or

create a Duplicate / Copy & Transform SOP and manage it in the network

It works, but it’s quite a few steps for something that in many DCCs is a simple gesture.

Requested behavior (viewport level, in Curve 2.0 / curve edit state):

With a curve object in edit mode:

If nothing is specifically selected, dragging the transform handle normally just moves the curve.

If I hold a modifier, e.g. Shift (or Shift+Alt), and drag:

Houdini creates a duplicate of the selected elements and moves the copy,

The original curve / segment stays where it was.

This would work at different selection levels:

Primitive / whole curve selection
Shift-dragging would duplicate the entire curve inside the same SOP and move the duplicate.

Segment / edge selection on a curve
Shift-dragging a selected segment would create another segment with the same shape, still part of the same curve object, and move it.

Point / subset of points selection
Shift-dragging selected points would duplicate those points (and connecting segments where possible), keeping the original topology intact.

For people who don’t know 3ds Max:
In Max, when you edit a spline, you can hold Shift while moving a segment or group of vertices, and it creates a new copy of that piece in one gesture. You don’t need to go through a separate “duplicate” tool; the modeling stays very fluid and interactive. The idea is to get a similar feel here, but inside Houdini’s curve states.

Technically it’s just a local duplicate + transform, but as a direct gesture in the viewport it speeds up shaping significantly.

2. “Extrude” curve segments by dragging

The second piece is an “extrude-like” interaction for curves.

Again, thinking in terms of viewport UX rather than nodes:

Requested behavior:

In curve edit mode, when I:

select an end point of an open curve and drag with a modifier, Houdini

creates a new segment,

adds new control points following my drag,

keeps tangents continuous.

optionally, when I select a segment and drag with a modifier, Houdini:

extends the curve by creating a new segment starting from that edge,

similar to extruding an edge on a polygon mesh, but in 2D/curve space.

From a modeling point of view, this lets you:

quickly “grow” roads, paths, outlines of buildings, graphic shapes etc.,

keep working in one curve object instead of constantly adding new nodes,

stay focused in the viewport instead of bouncing between handles and the network.

For users without 3ds Max background:
Think of it as taking an open curve, grabbing its last point or a segment, and pulling out more curve from it, with new points automatically created along your drag direction. No need to manually add points and reconnect them.

Why this would be useful in Houdini’s context

Houdini’s curve toolset is already very strong (Curve 2.0, Draw Curve, Polydraw, etc.). But most of the time, users still do a quick “direct modeling” pass before turning things into more procedural networks.

These two interactions:

Shift-drag duplicate, and

Drag-to-extrude segment / endpoint

would make that initial curve modeling phase much faster and more “sketch-like,” while:

producing the same kind of clean polylines we already work with,

not breaking the procedural nature of the scene (it’s just another edit operation in the Curve/Polydraw state),

and fitting nicely into the existing Python state system for Curve 2.0.

Even a minimal implementation as optional behaviors in the Curve 2.0 state (with checkboxes like “Shift-drag duplicates selection” and “Ctrl-drag extrudes endpoints”) would already be a big boost to the UX.

Thanks for considering it, and I’d love to hear if other people would also find this helpful for their curve workflows.

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