Wow, I shouldn't have wrote that late last night, I completely mixed
things up in my previous post, sorry!
I'll try again! With a ramp, you have the source (input) values on the
X axis, and the target (output) values on the Y axis. If either your
source or target values aren't in the range [0, 1], you can remap them
using a simple float parameter (to use as a simple multiplier if your
desired lower bound is 0), or a float2 parameter to precisely control
the desired range.
It seems to be a standard practice in Houdini since they use it for
some built-in nodes, such as the Pyro SHOP.
Andy, the O(N) thing got me thinking and realized that instead of
running the attrib wrangle in detail mode, which uses only a single
thread, it'd be possible to generate say 4 points and, in a point
wrangle, let each of these points process 1/4th of the array, thus
effectively running the same logic on 4 threads! Another attrib
wrangle is then needed in post to sum up the result from each point.
Well, in all honesty I don't think there'll ever be a use case for it :)
On 7 March 2017 at 01:14, Olivier Jeannel <[email protected]
<mailto:[email protected]>> wrote:
Ok we agree.
On Monday, March 6, 2017, Jonathan Moore
<[email protected] <mailto:[email protected]>> wrote:
As far as I understood it Oliver, the spline version of the
Houdini Ramp only operates in the zero to one range. You
re-fit the values pre/post/ or both to suite your needs.
I get that this doesn’t match the UX of FCurves in XSI, but
I’ve always understood Ramp’s in Houdini to be more of a lower
level discrete element in visual programing terms.
*From:*[email protected]
[mailto:[email protected]] *On Behalf Of
*Olivier Jeannel
*Sent:* 06 March 2017 17:31
*To:* Official Softimage Users Mailing List.
https://groups.google.com/forum/#!forum/xsi_list
<https://groups.google.com/forum/#%21forum/xsi_list>
<[email protected]>
*Subject:* Re: houdini question (and where to ask)
Not sure I get it Christopher (not in front of H)
Does your trick actualy change the graph visualy ?
In short, can I see the negative x & y values ?
On Monday, March 6, 2017, Christopher Crouzet
<[email protected]> wrote:
Indeed, which is why I mentioned the “detail” mode which
brings you back to O(N). Not saying that one approach is
better than the other though, only that it is possible.
On 7 March 2017 at 00:12, Andy Nicholas
<[email protected]> wrote:
Yep it is possible, but you wouldn't want to do it
because each calculation of the maximum value would be
running across N points to calculate that. That'd make
it an O(N^2) operation, albeit spread over multiple
threads.
It might seem like a pain to have to do this in
advance using an Attribute Promote, but by doing so,
it's actually forcing you to work in a more efficient
way. Go with it ;)
On 06/03/2017 16:32, Christopher Crouzet wrote:
It /is/ possible to retrieve the maximum value in
a VOP since nothing stops anyone from manually
iterating through all the points of the geometry.
This kind of operation might be more suited in
“detail” mode though.
Also, having the ramp normalized to the [0, 1]
range in both the X and Y axis is usually
“workarounded” by adding a float parameter for the
amplitude (Y axis) that is used as a global
multiplier (making later tweakings convenient!),
and a float2 parameter for the target range (X
axis) that is then remapped using `fit("my_ramp",
0.0, 1.0, range_min, range_max)` (which is also
convenient for later tweakings!).
Now, if you really want to have an actual FCurve,
then just create a simple float parameter, add all
the keys however you want, then query it in using
`chf("my_param", the_time_in_seconds)` in VEX/VOP,
or using the equivalent expression.
On 6 March 2017 at 23:29, Jonathan Moore
<[email protected]> wrote:
Fabricio ,
The Attribute Promote help page has approx 15
examples you can load. Hopefully you might
find something within the examples to inspires
a solution.
*From:*[email protected]
[mailto:[email protected]]
*On Behalf Of *Olivier Jeannel
*Sent:* 06 March 2017 15:56
*To:* Official Softimage Users Mailing List.
https://groups.google.com/forum/#!forum/xsi_list
<https://groups.google.com/forum/#%21forum/xsi_list>
<[email protected]>
*Subject:* Re: houdini question (and where to ask)
You can't get the "get maximum in set" when
inside a vop.
But, you get those options with the promote
attribute sop.
On Monday, March 6, 2017, Oscar Juarez
<[email protected]> wrote:
I would like to be proven wrong, but that
would be the way, I mean in your second
pointvop you don't need to add another
noise, your noise is already saved in an
attribute, when you promote just check off
delete original and you can access the
same noise. Also noises have specific
output ranges, they come in the
documentation, so you can always add a fit
node to change your range to what you
need, in the geometry spreadsheet you can
also sort by value so you can see max and
min.
If you press X with your mouse over the
noise output it will add a visualization
node, you can visualize on the viewport or
in the geometry spreadsheet the values. I
know its not the same but as far as I know
their is no way to do the same as the get
maximum in set node in a vopsop context.
On Mon, Mar 6, 2017 at 3:57 PM, Fabricio
Chamon <[email protected]> wrote:
thanks everyone. The ramp parameter
kind of works but as you say, is not
that user friendly and does not show
the points below 0. (that's ok, but I
wonder if it is possible to write a
custom widget in houdini)
anyway, the thing I could not get
right just yet is that sort of "get
maximum in set" thing. Sorry for using
ICE language, I'm trying to be open
minded here, so please tell me if
that`s not the correct mindset.
so on this graph:
Imagem inline 1
...how could I get the maximum value
of the output noise node and compare
to a single point output of the same node?
From what I can tell, I'd have to:
1- create this pointvop node with a
turbnoise, then store the output noise
into an attribute (via bindexport?)
2- up one level -> drop an attrib
promote (detail), set to maximum
3- drop another pointvop node with
another noise node inside (same
parameters) and compare the result
noise to that found on the atrib
promote node??
I'm 99% sure this is totally
wrong...how would you go about that
single task specifically?
and finally, thanks for the
suggestions on houdini forums and
discord. will try both (although I
pretty much like this list =) )
2017-03-06 15:17 GMT+01:00 gareth bell
<[email protected]>:
yeah - the lack of handles is
frustrating
------------------------------------------------------------------------
*From:*[email protected]<[email protected]>
on behalf of Olivier Jeannel
<[email protected]>
*Sent:* 06 March 2017 14:05:17
*To:* Official Softimage Users
Mailing List.
https://groups.google.com/forum/#!forum/xsi_list
<https://groups.google.com/forum/#%21forum/xsi_list>
*Subject:* Re: houdini question
(and where to ask)
yep but it has no handles
and try to make négative values,
it takes them but wont show on the
curve as it has a 0,1 space.
Unless i'm wrong (which i'd love
to be)
Le 6 mars 2017 14:36, "Olivier
Jeannel" <[email protected]>
a écrit :
in vop, bind and bind export
node will get an set datas.
Ramp Parameters is sort of fcurve.
It's a bit weak in terms of
curve manipulation, but does
the job.
It has 2 modes rgb (ramp) and
spline.
If you use several ramps in
the same vop, name them with
different name or they might
not export.
Le 6 mars 2017 14:28,
"Fabricio Chamon"
<[email protected]> a écrit :
..sorry, hit send too soon.
Question #1: are there any
equivalents to ICE "get
... in set"? or or do I
have to iterate and store
values for later
comparision? In other
words: what is the best or
recommended workflow to
compare single point data
with global point data?
Question #2: any nodes
that resemble a fCurve
node, like we have in ICE?
if not, what is the
alternative?
and finally, I can see
this list is becoming more
and more houdini-esque
than ever..but, what is
the best place to ask
beginner questions like
the above? houdini foruns,
houdini list, odForce...
thanks!
2017-03-06 14:23 GMT+01:00
Fabricio Chamon
<[email protected]>:
Hi, I'm slowly getting
into houdini and this
is my first attempt to
port a really simple
ridged fractal
deformer made in ICE
to houdini (using
pointvop).
Question #1: are there
any equivalents to ICE
"get ... in set"? or
or do I have to
iterate and store
values for later
comparision? In other
words: what is the
best or recommended
workflow to compare
single point data with
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