Mike_RB
Thanks again for the link. Here's just a ton of particles with 2 layers of wind with thier offsets animated. I love being able to dial up the birthrate to 30000…. nice.
http://www.elementvfx.com/WebDemo/foam.mov [elementvfx.com]

Nice again. Looks like you should be here for a long time now

Personally I hope SESI will provide Point Primitive with CVEX support soon, which would be crucial for such effects. Hopefully…

Personally I hope SESI will provide Point Primitive with CVEX support soon, which would be crucial for such effects. Hopefully…

Me too.

In the mean time you can generate a bunch of particle sprite sequences on disk and instance in to them with your seed particles. Yes you get large ifd's. Yes it is more work. But… You get a ton of control and you can actually prototype exactly what you want.
Then! You can tell us in fine detail what behaviours and controls you would like to see in a particle procedural so there can be good defaults.

Same thing, but with transparency on the particles.

http://www.elementvfx.com/WebDemo/foamarea_vol.mov [elementvfx.com]

Mike_RB
Same thing, but with transparency on the particles.

http://www.elementvfx.com/WebDemo/foamarea_vol.mov [elementvfx.com]

Are you using fields from fluid sim or just a noise pattern? If second is the case, look on Exchange for Ivan DeWolf's divergence-free noise:
http://www.sidefx.com/exchange/info.php?fileid=391&versionid=391 [sidefx.com]
and the paper: http://martian-labs.com/martiantoolz/files/DFnoiseR.pdf [martian-labs.com]

Pretty helpful in fluid-like stuff.

cheers,
sy.

jeff

Personally I hope SESI will provide Point Primitive with CVEX support soon, which would be crucial for such effects. Hopefully…

Me too.

Sounds promising

Grid, wire deformer, pinned corners, and particles. I can't keep some of them from falling through… but still cool…

http://www.elementvfx.com/WebDemo/clothnew.mov [elementvfx.com]

Looks cool

The best thing to do is ensure your cloth grid is made of triangles and turn up your Collision Tolerance a bit.

Jason beat me to it! In addition, you should change the Hint from Static Geometry to Deforming Geometry. It will be slower but hopefully will work better.

Good looking tests so far.

Cheers!
steven

Ill try that.

Can anyone tell me the basics on parenting things like spring constraints and wire pin constriants to animated objects (obj level transforms) (nulls, geometry).

And can someone point me in the right direction for adding a size attribute to particles, and them ramping it up over thier lifetime? Same with fading them out. That would a big help as the size thing seems to be stumping me.

Thanks.

M.

Hi there Mike_RB.

I don't now much (if anything at all) about Houdini, since I'm just beginning to learn it, but I've found it to be a very powerful 3d app. In my quest for learning material I ran into several sites with very good video tutorials. The first one is digitaltutors:
http://www.digitaltutors.com/digital_tutors/tutorials.php?cat=houdini [digitaltutors.com]
You can check most of their tuts through their “free tutorials” link. Or if you want the more advanced stuff you could order/download one of their CDs.

The other one is the video course available at 3dbuzz (you need to create an account in order to be able to downlaod their videos):
http://www.3dbuzz.com/vbforum/sv_dl_tr.php [3dbuzz.com]
Though the videos are for an older version of Houdini you can still follow and learn a lot form them.

I'm sure someone with your talent and experience will take very good advantage of those videos.

best regards,

Alvaro

Thanks for the links. I'm still in the play around phase mostly, but I'm sure I'll get to those eventually.

Here is a quick water sim using a particle fluid SOP to skin the particle system.

http://www.elementvfx.com/WebDemo/liquid_h9.mov [elementvfx.com]

Worked pretty well except you lose volume where they hit the wire object (cloth like grid below… thanks for the collision tips above seems to do a much better job). Is there a simple particle pressure or min distance I can add to force them apart so they don't bunch up?

Thanks again guys for all the tips. I'm already seeing how houdini could be used for some of the trickier stuff we run into, and with Eetu's .mdd plugins on odforce it should be easy to get geometry back and forth from LW/modo.

Is there a giant cache all to disk button somwhere? So I can render stuff out of order or rerender stuff and not have the sim change? Or does it have to be done piece by piece and/or even have the cached geo/sims imported back into the scene?

Thanks.

M.

I just found the interact behaviour. That should help my fluid volume problem I hope….

Hey Mike,

Mike_RB
Can anyone tell me the basics on parenting things like spring constraints and wire pin constriants to animated objects (obj level transforms) (nulls, geometry).

You can look into using the Rivet Object or Object Merge SOPs to read in the Geometry with World Space transforms with the centroid() function. Not real constraints like in other packages but should get the job done.

There are constraints in DOPs but that's simulation so might not be what you want. Else, please provide specific examples of what you want to do & we should be able to provide more information.

And can someone point me in the right direction for adding a size attribute to particles, and them ramping it up over thier lifetime? Same with fading them out. That would a big help as the size thing seems to be stumping me.

Look into using a Property POP, Misc tab & turn on Uniform Scale. You can use an expression like fit($LIFE,0,0.5,0.1,1) where $LIFE is in seconds or fit($AGE*$FPS,0,5,0.1,1) where $AGE*$FPS returns frame number which is easier to think in terms of, IMHO.

The same applies to Alpha but you can use the Colour POP with a Ramp control. Be aware of the Lookup parameter where it's based on the total number of frames so you should change it to $LIFE.

As usual, there are many ways to do what you want in Houdini so you can put down a Point SOP and control Alpha & Particle Scale too.

In each OPerator, you can click on the ? button in the parameters to get Help where there should be examples.

Hope the above helps!

Cheers!
steven

Mike_RB
Is there a giant cache all to disk button somwhere? So I can render stuff out of order or rerender stuff and not have the sim change? Or does it have to be done piece by piece and/or even have the cached geo/sims imported back into the scene?

For POPs, you will have to use a Cache SOP but everytime you change something, you will have to remember to hit “Clear Cache”.

Else, you can connect a ROP Output Driver to the POPnet or put down a Geometry ROP in the out network, write it to disk and read in with a File SOP. The File SOP has Read/Write options which is new in 9.1 but I don't ever use it.

Cheers!
steven

thanks for the particle and cache info, I'll try it out. Here is my smoke rerendered a little less thick. Pretty nice result and it renders decently fast.

The flickeryness is from the compresssion….

http://www.elementvfx.com/WebDemo/smoke_2nd.mov [elementvfx.com]

Simple RBD sim. Works nicely.

http://www.elementvfx.com/WebDemo/fall.mov [elementvfx.com]

stevenong
The same applies to Alpha but you can use the Colour POP with a Ramp control. Be aware of the Lookup parameter where it's based on the total number of frames so you should change it to $LIFE.

I can get a ramp set to color to affect the particles, but it seems like no matter what I put in the alpha ramp section my alpha is always pure white on the particles….. thoughts?

Hey Mike,

Someone had this same issue which I answered here [forums.odforce.net].

Cheers!
steven

Mike, food for thought. You may want to try playing with the particle fluids in DOPs if you want a more liquidy look than you had in your pops->particle fluid surfacer test.