[Sidefx-houdini-list] POP particles rotation situation here...

Javier Meroño javiermerono at hotmail.com
Thu Jul 14 15:45:15 EDT 2011


It makes sense. Thanks guys.

regards,

Javier Meroño

> Date: Thu, 14 Jul 2011 08:04:32 -0700
> From: tstexture at gmail.com
> To: sidefx-houdini-list at sidefx.com
> Subject: Re: [Sidefx-houdini-list] POP particles rotation situation here...
> 
> Yep,
> 
> To put it another way - with each cook of a POP network you sometimes
> want to add new values to the values from the previous cook:
> 
> $VX + $ADDX
> $VY + $ADDY
> $VZ + $ADDZ
> 
> Otherwise you are replacing the values built up over all previous
> cooks with new values.
> 
> Cheers
> 
> 
> 2011/7/14 Pablo Giménez <pablogipi at gmail.com>:
> > Well in big and small productions is handle in the same way: smart
> > expressions :)
> > AS far as I remember, I dont have houdini in front of me at the moment, what
> > I do to accumulate a values is always use the local variable and then add my
> > stuff, this will carry on the values for the next operators.
> > Rotation POP and Torque POP are complitelly different things. All operators
> > that modifies forces just pick up the current accel values and add it's own
> > force, this is the reason because you can mix them in the same network.
> > Different thing is for operators that directly sets an attribute. Like
> > velocity or rotation. It doesnt matter if you use expressions or a VOP POP
> > you have to carry on the previous values.
> > If you want to do this for the rotation angle in a rotation POP you have to
> > do something like: $ROTA + [myStuff]. And it should be able to concatenate
> > several rotation POP.
> > Same for other values.
> > For instance if you want to animate this rotation angle you can do it in two
> > ways:
> > $FF % 360
> > $ROTA + 5
> > Both eorks but the first just override the currentvalu with something that
> > is getting bigger in a sequence [0-359], the second add to the current value
> > 5 degrees. For me the second option is much better.
> > Well this what I remember now on top of my head, hope this helps.
> >
> > 2011/7/14 Javier Meroño <javiermerono at hotmail.com>
> >
> >>
> >> Here´s an interesting one I just bumped into.
> >>
> >>
> >>
> >> I want to add several (different) rotations to my POP particles. I
> >> noticed you can´t chain several Rotation POPs: it only applies the last
> >> one. My best guess being the reason for this is the Rotation POP assigns
> >>  the actual rotations to the particles, just like the velocity assigns
> >> velocity as opposed to being a force that adds to it.
> >>
> >>
> >>
> >> Hence, I go for the Torque POP, which indeed does work and allows several
> >> of them to be concatenated as they are forces.
> >>
> >> BUT, obviously I want to limit the Torque to one or two frames.
> >> Otherwise it adds up every frame and I get too much angular velocity.
> >> The problem being my particles are "activated" by putting them inside a
> >> group which is preserved.
> >>
> >> I solved the situation by adding another non-preserved group that activated
> >> the torque force.
> >>
> >>
> >>
> >> Is this how you usually deal with several rotations?
> >>
> >>
> >>
> >> Also, I would like the angular velocity to to get increasingly higher as
> >>  the particle moves more, so I add an angular velocity node and use
> >> something along the lines of
> >>
> >>
> >>
> >> $WA*(0.3*vlength(vector3($VX,$VY,$VZ)))
> >>
> >>
> >>
> >> which more or less works, with the exception of one or two particles that
> >> would require some "individual" love.
> >>
> >>
> >>
> >> All of this seems a tad messy and unelegant to me. How do you usually
> >> deal with this....do you go the VOP POP route? Just trying to understand
> >>  how it is usually done in big productions....
> >>
> >>
> >>
> >> regards,
> >>
> >>
> >>
> >> Javier Meroño
> >> _______________________________________________
> >> Sidefx-houdini-list mailing list
> >> Sidefx-houdini-list at sidefx.com
> >> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >>
> >
> >
> >
> > --
> > Un saludo
> > Best Regards
> > Pablo Giménez
> > _______________________________________________
> > Sidefx-houdini-list mailing list
> > Sidefx-houdini-list at sidefx.com
> > https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >
> 
> 
> 
> -- 
> =======================================
> Andrew D Lyons | Digital Artist | http://www.tstex.com
> =======================================
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