[Sidefx-houdini-list] sweep

François Duchesneau sidefx at trinix.ca
Tue Oct 11 11:38:37 EDT 2011


You can also use my Tx Curve Attrib tool that has a ramp to control any 
float attribute you add along a curve. You can visualize the result. If 
it's a vector, you can use it as a multiplier. It works with either the 
parametric position or the ratio current point/total nbr of point.

It's on www.trinix.ca under Tx Toolkit.

François

Jeff Wagner wrote:
> Look at the help for the Sweep SOP. There are some nice local 
> variables that allow you to process multiple curves easily.
>
> $PT returns the current vertex point along each backbone from 0 to n-$NPT
> $NPT returns the total number of points in each backbone curve.
> $PATH returns the primitive number if you want for example a random 
> seed for each backbone curve.
> $PCT is the percentage along the backbone for each curve.
>
>
> So in scale you could add a slight bit of randomness for each profile by:
>
> $PCT + if($PCT==0, 0, rand($PT + $PATH))*0.1
>
> with the if() statement to make sure that you add no random scale 
> value at the start of the curves.
>
> To make cubic tapered ends, you can gang two smooth() functions 
> together like this:
>
> (smooth($PCT, 0, 0.1) - smooth($PCT, 0.7, 1)) * 0.5
>
>
>
> -jeff
>
> On 11-10-07 3:39 PM, zoran arizanovic wrote:
>> thanks larry
>> :)
>>
>> On Fri, Oct 7, 2011 at 9:29 PM, Larry 
>> Giunta<larry at gcreativestudios.com>wrote:
>>
>>> Hey Zoran,
>>>
>>> If I understand correctly, I've done something like this before by 
>>> adding
>>> an expression in the scale parameter on the Sweep SOP.
>>>
>>> In my case I needed it to be consistent for most of the curve, then 
>>> scale
>>> to a zero at the end. So I enclosed it in a clamp function.
>>> Something like this.
>>> clamp(($PT*.1), 0, 1.5)
>>>
>>> Larry
>>>
>>> -- 
>>> Larry Giunta
>>> Creative Director
>>> G Creative Studios
>>> (978)276-0600
>>> www.gcreativestudios.com
>>>
>>>
>>>
>>> On Oct 7, 2011, at 3:03 PM, zoran arizanovic wrote:
>>>
>>>> hi
>>>> I would like to control thickness-diameter of crosssection circle
>>>> I have a circlethrough sweep sop  along dynamic curves and would 
>>>> like to
>>>> control it so  it goes gradually to zero on the top of a curve
>>>> so the sweeped geo would be the thickest at point0 and  zero scale at
>>> point
>>>> X-end point
>>>> thanks
>>>>
>>>>
>>>> -- 
>>>> Zoran Arizanovic
>>>> vfx reel : http://vimeo.com/28605448
>>>> http://www.imdb.com/name/nm2902303/
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>>
>>
>
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