Curves in Houdini


use Bezier curve if handles and precise control is needed!! (nurbs curves have no handles!!)



connect 2 curves to single curve

add 2 curves (or labs spiral) add fuse node group: select the 2 endpoints uncheck snap distance

check if multiple primitives

click on display primitives numbers icon (on right side of viewport) add polypath node to connect the 2 curves

create rounded corners from pointy shape

add bezier curve node then click a couple of times to draw something hit F key and select a point click on Create Rounded Corners Icon then drag the big middle point to set a corner radius then adjust shape by moving points, which will keep radius!

adjust radius to relative value

hold down crtl and drag middle point

remove the rounded corners

click on remove rounded corner button

convert to adjustable points (with handles)

select points parameters -> rounded corners (at bottom) -> click bake selected rounded corners

use for:

quick bottle shapes, organic shapes architecture, mechanical stuff use this to create a bottle shape really fast, by clicking together a couple of points, then selecting all points and round them

draw curve

add curves node primitive type: bezier hit ENTER when done hold down crtl + shift to change corner from bezier to square hold down A key to get arc

edit/move points

hit F key, then click on points and move them (don't use edit SOP) shift + click on curve to select all points

quickly change tangents

hit F, select a point then use shortcut 1 2 3 to Make Corner / smooth / balanced hold down crtl + shift to only adjust length of handle hold crtl to break tangent

add points

holding crtl and clicking on curve

add new points at beginning or end

hit G, then click on end point to continue drawing

join curves

add 2 curves hit F key, right click -> join points


add merge node then in viewport editor add join node


add fillet curve to join 2 curves with a new segment

move curve

hold shift and click drag press K to bring up transform tool ... add another curve node for easy editing

prepare curve for sweep node

(polyextrude does resample automatically, but not sweep) create curve for cross section and another where it should flow use transform node to align the cross section curve feed them into sweep node (click display primitive hulls icon on right side of viewport to see the control polygon that is used for the cross section) add resample node (this converts the bezier curve into a polygon curve) uncheck maximum length check maximum segments (convert node works too) add refine node (removes points which are not needed, lower res) first U: 0 second U: 1 unrefine tab -> tolerance U: 0.001 (adjust this parameter until points only remain on curve and none on straight lines)

for adjustments of curves

add another curve node below original one


use Edit node (if using older Houdini Verions < H19)

flattening curve on one axis

add transform node scale: 1 0 1 (to flatten Y axis)

draw curve through specific points

check Auto Bezier Draw mode and click on points

cut away a part of curve

add carve node use FirstU and Second U for start/end points alternatively use clip/knife node (also add a resample node because clip/knife can only operate on a polycurve)

create a cross profile with 2 curves

add 2 curves, one for top view and one for side view add resample node after both curve nodes (this converts the bezier curve into a polygon curve) uncheck maximum length check maximum segments add them to skin node

extract or copy a curve from geo

press 3 to go into line selection mode make a selection (shift + a) tab -> edge group to curve node (labs tools) (easier to use than dissolve node)

Published: August, 2022