Here's my way:
1) emit particles (set an expression or keyframes on velocity so that at a
certain frame velocity becomes 0)
in this example I am setting keyframes, you can see velocity {{curve x1 1
x20 1 x21 0}}
this reminds me to ask to Foundry to add to the ParticleCurve a "vel"
attribute as I prefer to do it there with a real curve.
2) I use a ParticleSpeedLimit to stop particles being emitted (funky way)
3) an expression on ParticleExpression sets vel = 0 after frame 20
frame>20?0:vel
4) an expression on ParticleGravity has them being affected by the field
after frame 40:
frame>40?-1:0
Have fun,
P.
#!
/Applications/Nuke6.3v7/NukeX6.3v7.app/../Nuke6.3v7.app/Contents/MacOS/Nuke6.3v7
-nx
version 6.3 v7
define_window_layout_xml {<?xml version="1.0" encoding="UTF-8"?>
<layout version="1.0">
<window x="0" y="22" w="1680" h="1024" screen="0">
<splitter orientation="1">
<split size="977"/>
<splitter orientation="1">
<split size="40"/>
<dock id="" hideTitles="1" activePageId="Toolbar.1">
<page id="Toolbar.1"/>
</dock>
<split size="933"/>
<splitter orientation="2">
<split size="1002"/>
<dock id="" activePageId="Viewer.1">
<page id="Viewer.1"/>
</dock>
</splitter>
</splitter>
<split size="699"/>
<splitter orientation="2">
<split size="587"/>
<dock id="" activePageId="Properties.1">
<page id="Properties.1"/>
</dock>
<split size="411"/>
<dock id="" activePageId="DAG.1">
<page id="DAG.1"/>
</dock>
</splitter>
</splitter>
</window>
</layout>
}
Root {
inputs 0
name /Users/poli/stop_and_run.nk
format "2048 1556 0 0 2048 1556 1 2K_Super_35(full-ap)"
proxy_type scale
proxy_format "1024 778 0 0 1024 778 1 1K_Super_35(full-ap)"
}
Viewer {
inputs 0
frame 1
input_process false
name Viewer1
xpos -853
ypos -471
}
Sphere {
inputs 0
name Sphere1
xpos -1031
ypos -609
}
push 0
ParticleEmitter {
inputs 2
lifetime 100
velocity {{curve x1 1 x20 1 x21 0}}
name ParticleEmitter1
xpos -1031
ypos -568
}
ParticleSpeedLimit {
minimum 1
maximum 0
name ParticleSpeedLimit1
xpos -1031
ypos -523
}
ParticleExpression {
velexpr frame>20?0:vel
name ParticleExpression1
xpos -1031
ypos -468
}
ParticleGravity {
to {0 {frame>40?-1:0} 0}
name ParticleGravity1
selected true
xpos -1031
ypos -411
}
Scene {
name Scene1
xpos -1117
ypos -394
}
On Thu, May 17, 2012 at 7:44 PM, Sean Brice <[email protected]> wrote:
> If you want to elongate the freeze (taking place at frame 20 in that
> script), you just have to change the ParticleExpression chans knob to tell
> it when you want to place the particles in the 'b' channel being acted on
> by the downstream forces.
>
> i.e. change the 'chans' knob to frame==30 if you want it to freeze for
> 10 frames before the ParticleGravity kicks in.
>
> Cheers,
>
> Sean
>
>
>
>
> Sean Brice wrote:
>
>> Hi Guys,
>>
>> Ari, if I follow you correctly you can use a combination of a
>> ParticleDrag node and a ParticleExpression node (to change the channel the
>> particles are in at a particular frame), then apply the forces to that
>> channel downstream to get what you are after.
>>
>> Have a look at this example Nuke 6.3v7 script. Is that what you want?
>>
>> Cheers,
>>
>> Sean
>>
>>
>>
>> Moritz Moeller wrote:
>>
>>> On 5/17/2012 1:20 PM, Diogo Girondi wrote:
>>>
>>>> A "hold" node for particles would be great.
>>>>
>>>
>>> Can't a particle expression be used to set velocity to zero?
>>>
>>> .mm
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>>>
>>
>>
> --
> Sean Brice, Product Designer
> The Foundry, 6th Floor, The Communications Building
> 48 Leicester Square,
> London, WC2H 7LT, UK
> Tel: +44 (0)20 7968 6828 / Fax: +44 (0)20 7930 8906 / Web:
> www.thefoundry.co.uk
>
> The Foundry Visionmongers Ltd / Registered in England and Wales No: 4642027
>
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>
--
paolo berto durante
space cowboy
/*jupiter jazz*/ visual research — hong kong
http://jupiter-jazz.com
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