[Sidefx-houdini-list] Spare ramp param question

Alex Czetwertynski alex at franktheplumber.com
Tue Jul 20 19:00:10 EDT 2010


Ahh!
That definitely helps, I was misinterpreting the docs, I thought the second
value needed to indicate the position of the point on the ramp you wanted to
use, but using $LIFE or another time based param makes sense.  Still getting
those concepts to burn into my brain.

Thanks a lot



On 7/20/10 3:50 PM, "Stephen Tucker" <stucker at allegrodigital.com> wrote:

> 
> ramps map values between 0 and 1,
> so for example if you wanted to map the Alpha of a particle over it's
> lifespan, in a point sop you could use:
> 
> chramp("rampparameter", $LIFE, 0)
> 
> where:
> - rampparameter is the path to your ramp parameteter
> - $LIFE is the normalized age/lifespan attribute that you get for free with
> particles
> - 0 is the index of the ramp (rgb = 0,1,2)
> 
> If you want it to map with Time, which maps between 0 and 1 over the course of
> the first second and afterward will give you bogus values as far as your ramp
> is concerned... you need to find a way of normalizing your time to be in the
> range of 0 to 1, by using another expression such as $T/$TEND as your seed.
> 
> Hope that helps
> 
> 
> 
> 
>> From: alex at franktheplumber.com
>> To: sidefx-houdini-list at sidefx.com
>> Date: Tue, 20 Jul 2010 22:41:01 +0000
>> Subject: Re: [Sidefx-houdini-list] Spare ramp param question
>> 
>> Thanks Steve and Alex, that was quick!
>> I guess my question might not be as simple as I thought...I was under the
>> impression I could simply refer the External Force to the Ramp, and it would
>> evaluate it over time..But it looks like chramp() only takes one particular
>> position on the given Ramp?
>> 
>> Thanks
>> Alex
>> 
>> 
>> On 7/20/10 3:31 PM, "Alex Lim" <list at poh-yee.com> wrote:
>> 
>>> Hi Alex. Perhaps chramp() is what you're after?
>>> 
>>> Cheers, Alex
>>> 
>>> 
>>> 
>>> On 7/20/2010 3:28 PM, Alex Czetwertynski wrote:
>>>> Hello
>>>> 
>>>> I'm trying to create a simple channel reference to a spare ramp param I
>>>> created in a POP SOP.  I basically am linking the External Force to a ramp
>>>> I
>>>> created and using ch("./myramp") in the Y value of the External Force.
>>>> What I can see is that the value I'm getting out of that is 2, which I
>>>> assume it is getting from the number of points in my ramp, not the ramp
>>>> values....What am I doing wrong?
>>>> 
>>>> Thanks
>>>> Alex
>>>> 
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