inverse disintegration

[sbjones25]

Hello all, I am hoping that someone out there will be able to help me solve my problem. I am trying to do the reverse of a disintegration effect, but have racked my brain for every possible solution. As most have seen sand vase disintegration by Miguel (Attached), I am trying to do the complete opposite. I am trying to have points start out sporadically and based on a mask going across the geometry, integrate (or come together on the surface of the geo) and stay. What is the best possible way of accomplishing this effect? My closest trials have been creating the simulation that I want, in reverse. Bake the particles out, batch rename the baked particle files so that they are running backwards when I pull them back into Houdini. This strategy hasn't been that successful, but it's the closest I've gotten. The problem with this strategy is that I can't use a RenderPOP to render my particles, because they are at the GEO level (once pulled back in), not the POP level. I also don't have any control over the particles once baked out. Time remapping the simulation in post won't work either, because I have camera movements that need match. Attached is the disintegrating vase that I'm using for reference. Any and all help would be greatly appreciated. I know that this is kind of confusing, but I don't know how else to explain it. Hope this makes sense.

Thanks Again,

Stephen

sjones@thedvigroup.com

Any hip files would be most helpful as I am still trying to learn all of the ins and outs of Houdini.

[pencha]

Depending on the trajectory you need, you could do a per-point "blendshape" based on a custom attribute in VOPS, use a POP simulation as a source or just add some layers of noise inside te VOPS and check that the noise amplitude is 0 when the points reach their destination.

[loudsubs]

If you have already created the reverse of the effect you want, just bring that animation into CHOPs with a geometry chop. Under the common tab, change to frames, then under the channel tab, set the start and end range. sample rate is FPS. append a stretch chop and check the "reverse interval" box. This will reverse the animation curves. Bring it back into sops with a channel sop. "Method" for the geometry chop and channel sop should both be "animated".

Would you mind sharing your method for the disintegration effect?

[anim]

if you have already baked your particles you don't need to batch rename the files to get backward effect, just change the expression in file SOP to import them bacwards

it your export sequence is for example $HIP/geo/file$F4.bgeo and range 1-100 it will give files file0001.bgeo - file0100.bgeo

so in File SOP use expression $HIP/geo/file`padzero(4,101-$F)`.bgeo and you'll get file0100.bgeo - file0001.bgeo

then instead of Render POP you can use Primitive SOP and in Particle Tab you have the same controls as in Render POP

but you don't have to use it if you want to render just points, just check Render As Points in your object's Render/Geometry Tab

then for controlling attributes you have many tools in SOPs like Attribute Create, Point SOP, or the most flexible VOP SOP

you can use lifespan and age of the particle to calculate any attribute along particle life (but remember that life now goes backward so count with this)

you can easily negate velocity vectors to give you correct motionblur

you can play with pscale, Cd and many other attributes with high flexibility

i always use SOPs for that, because it gives me control over entire particle sim look without the need of simulating it again

the other way is to use Attractor POP or custom VOP POP to attract particles to form your object

or as others said use blendshape or CHOP techniques, but then you need to have constant particle count across the whole simulation