Hi Tim,
Did you notice that you can do per-point array attributes in VEX?
There's nothing stopping you setting up position vector arrays on each
point, just like in ICE, and then using a Point Wrangle at the end to
use that array to generate a polyline. The problem is that you then have
to write all those handy ICE nodes like "Simulate Strands", etc. yourself.
That's why generally, you're better off just trying to use polylines as
a primitive as they're more supported by Houdini's other frameworks
(e.g. wire solver) and constraints.
A
On 02/03/2017 12:19, Tim Bolland wrote:
Thank you guys this was just what I was after. I'm aware that
ICE Strands are just arrays, but after playing around with Houdini's
VEX/VOPs framework I'm even more impressed by the way ICE handles the
per-point / per-point-array / per-cloud context switches. Houdini
seems kind of limiting in how you can't set global arrays within a
loop running over over the points or prims. I realise that there's a
detail mode, but doesn't help if your doing per point stuff as well.
Anyway, I diverge. I'm going to crack on and see what I can come up
with. I'm not such a fan of the solver/add point method as I like to
keep things as interactive as possible.
Also, I've found this... Has anyone seen it yet? It's a rewrite of
Kristinka but for Houdini.
https://www.sidefx.com/forum/topic/42665/
kristinka and few questions | Forums | SideFX
<https://www.sidefx.com/forum/topic/42665/>
www.sidefx.com
Hello, first of all, something I believe it is a good news. I'm close
to finish a ‘port’ of Softimage ICE hair styling system called
Kristinka Hair, to Houdini.
Cheers,
Tim
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<[email protected]>
*Sent:* 02 March 2017 12:01
*To:* Official Softimage Users Mailing List.
https://groups.google.com/forum/#!forum/xsi_list
*Subject:* Re: [Houdini] Working with strands the Softimage way
One other thought with regards to Strands in Houdini is that the
Softimage concept of Strands is supported via Redshift (with all the
same Strand primitive types). This stops you from having to use a
Polywire to create geometry from your curves and is far more efficient
as the Polywire SOP is quite slow.
Most of the tried and trusted methods for the creation of trails in
Houdini rely on the Point and Solver SOP's in combination with an Add
SOP. They work well but the Point Sop is single threaded and has been
replaced with the Attribute Expression SOP which is VEX driven rather
than HScript and fully multithreaded.
http://www.sidefx.com/docs/houdini/nodes/sop/attribexpression
Nils Prayer uses trails techniques a lot in his work and had a great
site - Scatter (a lot like Entagma) that shares some great techniques
that can be adapted for Redshift (you can of course follow the Mantra
way of doing things too).
http://www.scattertuts.com/tutorials/
<http://www.scattertuts.com/tutorials/>
Tutorials — SCATTER <http://www.scattertuts.com/tutorials/>
www.scattertuts.com
Behind the scenes News Downloads
The H16 build of Redshift only works with the initial release builds
not the nightly builds so H15.5 and Point SOP may be your best option
at this stage for trails/strands using Redshift but H16's certainly
worth a play if you don't mind keeping multiple builds of Houdini
installed (they're all discrete and don't interfere with each other).
https://www.redshift3d.com/forums/viewthread/11210/
On 2 March 2017 at 11:29, Tim Borgmann <[email protected]
<mailto:[email protected]>> wrote:
From what I discovered so far in Houdini I would say there are a
lot of different ways to create something like strands. The main
difference is that there isn't something like an array of
strandpositions (or an array of what ever strandproperties).
Instead there are simple point positions which are connected. That
means that if you want to control each strand and it's positions
(or whatever properties) seperately you have to asign something
like a strand ID by yourself. An easy way to do this is by using
the resample node for example. You set a 'curve number attribute'
with it. Also it has the nice 'curve u attribute' (same as strand
ratio / length).
So I would say the main difference is that you do not deal with
arrays (of strandproperties) but with normal point properties
which you have to organize by yourself.
A very basic way to create strands is the volume trail (you
mentioned) or also by using a simple solver to build up something
like the generate strands trail ICE node (than you can use the
original point ID as strand ID). Also the use of the basic add
node is possible to connect the points. But there are so many more
ways in H as usual :)
Also regarding the polywire, depending on the renderengine you
plan to use and the look you are after you don't have to use the
polywire at all, but can render the curves directly.
Best
Tim
Am 02/03/17 um 12:05 schrieb Tim Bolland:
Hey guys, I'm after a little advice. I'm currently looking at
building a some nice fluffy clouds made up of strands and from
what I can see there a load of different ways to achieve
something like this Houdini. Quite of few of the results I've
seen demonstrated online are achieved by creating a velocity
volume and drawing these the velocities out. These look nice but
I cant really figure out a way to edit them afterwards. Other
methods I've seen that look promising take points and running
them through a Polywire, however there seem to a load of ways to
group these points together and nothing is as succinct at
position / strandposition
What I'm wondering is what do you recommend? Is there a method of
strand creation / manipulation that gives you a nice amount of
flexibility and control? I've always been a huge fan of ICE
strands, and the concept of starting with some points, building
up strandpositions a long these points and controlling the
properties of the strands by either the point ID or the
strandposition ID.
From what I can see there is not equivalent workflow that I can
find, at least not out of the box. I can make polywires with ID's
and manipulate this, but I'm still a little confused about the ID
vs strandID context equivalent and how to manipulate each of
them. Any advice would be appreciated.
Cheers,
Tim
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