Deborah R. Fowler
Houdini Tips and Tricks related
to modeling / procedural modeling / procedural animation:
Posted 2013
Updated on Nov 5 2024
Files created by Deborah R. Fowler unless
otherwise noted. Click on
Picture for sample hipnc file
See also modeling
overview section
TIP:
add node can be used for many purposes. A better roof
example uses the add node as well (For other roofs see
below)
add node for deleting all but points
add node for following geometry
(we will use this extensively with animation).
alembic files - when exporting from
Houdini - use an rop alembic node to export - when
reading back into houdini use an import and be sure to grab
the correct path. More information about alembics here
animation misc - curve
movement
attribute
paint and the bend node H18 -
following Jeff Lait's
Masterclass on Attribute Paint - quick sample file - more info here
bend
with variation in a for-each pigFlower.hipnc
(H18.5)
boolean
booleanExampleH19.hipnc
box
(Polygon) geometry: If your corners look soft - like this you can check off the consolidate
corner points to get a more normal looking render like this. there of course are other ways
to deal with this - the Houdini theme - there is more than
one right way - it depends on what you are trying to do.
You can turn off consolidate points or you can use an
edgecusp. See hipnc for multiple solutions
bbox function
- like the point function, the bounding box function
can give you access to information you may need (see also
intersection analysis)
callback scripts - very simple example in
hscript and python of a callback script. A more advanced
python version exists on my python page here (see
Adding callback scripts). Another example DoorPlacementWithCallback.zip
callback to reset
parameters in the GUI (also included: how to make a
parameter disappear based on another)
-
cull geometry points by camera
frustrum (several videos exist on youtube, but here is a sample
file - see also Complex
Scene Tips -
table
legs example using ch reference or add 
CHOPS hints. The
limit node can come in handy (thank Ian), however there
usually is a mathematical way to achieve the same purpose
(both included in the hipnc file) - the goal was to flatten
the peak of a sine curve).
In
addition, you can use chops and take the information
to create a curve to build geometry (updated with pointwrangle
and op: format)
Here is a simple wing animation
using chops compared with expressions (updated using
for each in place of copy stamp)-
chops
combine for pause effect on sine function
chramp color
function additional file now in 19.5
chramp
float function in both hscript and vex now in 19.5
clip node
color node with
Attribute Create can also be used for similar control to the
chramp example above
color
variation using for-each (see also looping overview) exampleOptionsColorVariation.hipnc
(H18.5)
color
variation using for-each tint texture (see also looping overview) colorVariation.hipnc
(H18.5)
- [Tips for] Complex Scenes (Includes brief Render Description)
copy node - simple examples
(remember to use packed primitives or instancing - see
instancing)
copy node overview for
beginners (version 19.5) at Overview-CopyNodes.html
copy node
variation without stamping
copy by for each
with differing floor sizes - similar to the snowman/building
pointwrangle example
copy by for each with differing width
(similar to above but perhaps buildings)
copy
increase/decrease - now with for-each forEachIncreaseDecrease19.5.hipnc
creep sop (hint - inside this
file is a link to a forum post where they create a chain). More on creep here.
-
delete attributes (or
Attribute rename)
delete
or blast You can delete
or blast including
the second input for a bounding geometry object
- edgecusp
- see entry under Box above. Edgecusp, facet and vertex can
all be used to "sharpens edges by uniquing their points and
recomputing point normals". Also from sidefx documentation stairsFromSidefxDocumentation.hipnc
labs grab an edge
- if you have SideFXLabs loaded use edge group to curve,
you can create geometry from an edge labsGrabACurve.hiplc
font
node - should you ever need to randomize alphabetical
characters here are some expressions you may find useful- for-each nodes page containing multiple example files see Overview-Looping.html
- also loopForEachVaryStacks.hipnc
- simple example of randLineLength.hiplc and with sweep/polyspline nodes randLineLength.hiplc
fuse node can
be very useful to get rid of duplicate points - note H18 -
fuse behavior has changed - See below
fuse node H18 turn off everything
except Fuse Snapped Points
gears
- example using polyextrude, boolean, groups
glass - dealing
with glass? check out
the troubleshooting page
groups
can be very useful- FOR HEIGHTFIELD example files see here
Hscript
- including multi-line, comments and the for loop in a
parameter expression. There is a very useful forum post here
as well.
Hscript - example
above extended to a modular version
Hscript
- introducing some examples using C++ like hscript as
well as introducing pointWrangle (lecture example)
Hscript versus python
intersection
analysis
intersection
analysis for procedural animation
intersection
analysis for procedural animation
object
merge is
very useful to have tidy networks and reference geometry
without bringing all the nodes into the current container- Orient objects or profiles to a curve? copy to curves is not the only option
orient PolyFrame from above
video
orient PointWrangle from above
video
polyframe
or pointwrangle works, below are polyframe and for pointwrangle
click here- also now we have copy to curves node polyframeVSpointwrangleNCopyToCurve.hipnc (H18 and up)
- if you need meta data, instead of copy to curves, use orientAlongCurve.hipnc
(H19 and up) and copy to points
polyframe is
your friend (sometimes)
also orienting along a circle
tube geometry 
copy
onto curves configured in any "tube" shape
this works too - center of each
face (facet node used)
in more detail using lines or
expressions - (measure node used)
this works for
angled tubes as well (facet node, tube node)
- you can also use the sweep node
- (for H18 see attribute paint above) paint node can be used for layout - it is a very powerful technique, especially when combined with the scatter node. See attributePaintLayout.hiplc.
point
function
is an extremely useful function that you should be
aware of to get even more information- polyextrude - more info here
- points from volume -
more
info here
polyfill (polycap) roundedFace.hiplc
(H19)
polyspline
post placement
Building -
simple examples of placing posts on a platform both from an
edge or from the center- python versus hscript expressions
- PYTHON IN HOUDINI
rand
- (H19 file) seed can vary
(point wrangle, create attribute, attribute randomize)
roof -
fancy and also roofsFancyMore.hipnc
with a reamp controled version of a roof
sample windows Building (see
also building video) - windows using expressions and
lines and **pointwrangles** see also Building
Overview
sample side windows Building - side window (on depth) example
- using expressions and lines - two
solutions (in H13)
sample side door Building - side door using
lines (in H18) Click here for more on the point wrangle
version
sample
door (based on copynum) or a fancier one using callbacks
DoorPlacementWithCallback.zip- scatter node can be very useful for layout. Particularly when combined with the paint node (see above under paint) [scatter node has changed in H14 ... or the nearest neighbor information to control clumping/intersections (see scatterSolution.hipnc under instancing examples).] You can also scatter in a volume (using isooffset with scatter or pointsfromvolume)
- scatter (new in H15 behavior and ocean) - NewScatterAndOceanH15.hipnc uses attribute interpolate node to ensure points follow surface
- sample side justify sideJustify.hiplc
timeshift
-
stairs
- switch node switchNodeExample.hipnc
- transformation order matters (and remember to model at the origin, not off in space). See transformOrderMatters.hipnc.
transform teapots (order matters)
TeapotTransforms.hipnc
(H18.5)
- trim versus cookie. Nurbs are your friend. Here is an example file using project, trim, bridge and skin. A simple example is given as well as one I made for a student to show the differences between cookies and trim. (Cookies are fine but can sometimes create poor topology.) Here is a simple example of using trim trimCurves.hipnc and a bit more complex one trimmedNurbVersusCookie.hipnc (as pictured)
- visualize an attribute see here
and here
- wire example using a lattice node (thanks to Nate and Zak) and my version springTest.hipnc using a wiredeform node
