Smoke questions..

[crahzz]

Hey Folks,

It's been a few days mucking about with the smoke system in Houdini. I'm still trying to achieve a somewhat realistic simulation of how a space nebula would work. However I've run into some problems which I cant seem to fix, its become too specific for tutorials.

The thing is - I have 3 emitters, for 3 types of elements, and I want them to each emit a different density of smoke. Now, the only way I've been able to do this is to create 3 different popnetworks and linking those in 3 different smoke systems (all within one autodop) However, splitting the popnets apart made me lose the ability to use the proximity node (which I intend to use to create some forms of gravity - the heavier elements pulling in the smaller ones (even though at this point I dont know how)). But - if I put all the particles into 1 popnet Im no longer able to give it different densities.

So I'm stuck with either trying to visualize the particles correctly - but having incorrect motion or the other way around. I've attached the file what I have so far so you guys can take a look =)

Cheers

nebula_SmokeLarge.hipnc

Edited September 24, 2010 by crahzz

[tony]

Hi,

If you put all of your POP networks inside one and use a collect node at the end to link them all together you should be able to use the proximity node. Then after your POP network you can delete points based on their birth groups (for example delete everything but the helium particles). Now you can feed these separate groups of particles into DOPS. I've added an altered version of your hip file to do this. Hopefully it's what your after.

Cheers

Tony

nebula_SmokeLarge_ALTERED.hipnc

[crahzz]

Thanks tony. In the meantime I found another way to do it but this seems to be pretty clean and effective - Probably going to build on that. Currently however Im stuck with coloring the smoke - because I have no idea how to; seems it keeps rendering it as white smoke which is not what I want. Can anyone tell me where to properly set smoke color so it will show up in the render?

[bunker]

Simply create 3 scalar fields ( Cd.x Cd.y Cd.z ) in SOPs

or in DOPs, create a vector field named Cd

merge these 3 fields with your density

The color is then picked up by the standard smoke shaders

Thanks tony. In the meantime I found another way to do it but this seems to be pretty clean and effective - Probably going to build on that. Currently however Im stuck with coloring the smoke - because I have no idea how to; seems it keeps rendering it as white smoke which is not what I want. Can anyone tell me where to properly set smoke color so it will show up in the render?

[ikarus]

Simply create 3 scalar fields ( Cd.x Cd.y Cd.z ) in SOPs

or in DOPs, create a vector field named Cd

merge these 3 fields with your density

The color is then picked up by the standard smoke shaders

on top of this all you need to do is then transfer the Cd attribute from the particles to the color field, using a pointcloud lookup or one of the new H11 sops

[crahzz]

Thanks for the help guys - I appreciate it. I looked into the pointcloudlookup (which in h11 is now a rather complex VEX network - and by that I mean too complex for me) so I'm not sure how to figure this one out. So that kind of makes me stuck again haha. I'll just wrestle with it again and hope I win this time =)

[crahzz]

Just figured I'd attach the file in case someone was feeling especially generous haha.

In case people are wondering - this is the last thing I need to do before I can graduate as a concept artist from a dutch game design school - Some of my work can be found here: www.crahzz.com So as a mere 2D simpleton all this houdini stuff stresses my brain out. Already a big thanks to everyone who replied and lend me a hand.

TLunter_Nebula_Sep28_2.hipnc