Hi..

First of all… I have to say im new in houdini

Im driving myself crazy over here…

I have a bunch of geometry created by a copy sop… This creates me different circles/squares with randoms colors… (color points)

Now… i Would like to use this geometry as a volume emiter… and in each shape emit the smoke with the color of the shape…

Im in the point where i have all the volume in white… Is there a simple and effective way to do this?

Cheers

Probably a better way, but off the top of my head did it like this..

Hi Mr. Dean

I think i didn't explain myself…

I want to use the color not in a smoke object… I want to use it in a smoke simulation… That still image is from the dopnet!

In my ignorance, for testing, i create a color node after the fluid source, and put it red… but in the dopNet it remains being white!

This thread might be what you are looking for:-

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&p=117893&sid=741a85ec08611f6aa476910eed25e6b0 [sidefx.com]

Hi Mr Dean.

Thanks for your reply again

Yes… i assume thats the solution… However i dont understand it!

I dont have any clue how the Sop Vector Fiel, Vector Fiel visualization and Gas Advect works…!!

Is a lot of new stuff i dont have a clue… And the info provided by the Houdini Help icon doesnt explain to much either!!

Ill keep trying this method and ill Keep you posted!!!!

Again, a Trizillion Thanks!

Hi again

I've trying to replicate node by node and nothing

I did manage to transfer some color but it doesnt remain in the color… as soon the smoke is out of the emission volume it goes white

Also.. when i create a dop import for the smoke object it remains being white!!!!!!!!!

This is driving me crazy

What should i've been missing?

It can be a dozen*) different things - best to attach your scene file so we can take a look.

*) with “dozen” I mean a hundred

Here is the smoke part of the scene!!

Thanks to all in advance

Anyone ? :cry: :cry: :cry: :cry:

So correct me if I am wrong, you would like volume to inherit color from the emmiters and simulation to carry that information and maybe blend colors etc.

There are several examples out there, which i cannot find right now. but there is usually a two way of doing this. one as a volume attribute, for example like temperature. the other one is more simple, do your simulation first , then use your simulation to advect points with the proper color inherited from the emitters and sample colors from these points into your volume sim.

Hi tricecold!

Yes.. i want to do exactly that!!

i've only found and example of the gas advect, and the result of that is my example above…!!

The second option looks very awsome!!! But i dont know how to use the simulation to advect the points!…

BTW AWSOME reel!!!!!!!!!!!!!

Cache your fluid simulation first
then make a new popnet
Use your emittion geometry as source for points and if source is colored particles will inherit the color

after the source node for pops use a popadvectbyvolumes and play wwith the settings to make particles follow the volume.

This method will not blend the colors
after cache the points,
and in volume shader u can use pointcloud to sample colors

Wow… Didnt think of that!

I'll try it and i'll keep you posted!!

Thank you very very very very MUCH!

Just a little thing to add, which hopefully clarifies a small part of the issues you are running into. All volumes use voxels to store the data moving through them, and each voxel can have only a single value.
At the sop level, if you hold the middle mouse button on your fluid source sop you will see a list of Volume Resolutions. If you have a basic emitter with density, temperature and velocity, you should see them all listed. Strangely velocity is 3 separate volumes. But actually, it isn't that strange when you remember the previous rule: each voxel can have only a single value.
If you truly wanted to simulate mixing fluid colors you would need to create it as 3 separate volumes.

Density being white by default, is just that, the default. You could view it as any color, but since it's only a single volume it can't be anything more than that.

The last step you mentioned, getting your color data OUT of the DOP network to render is just a matter of setting your dop import fields node to import the right volumes. By default is isn't looking for a color volume. But if you have it in DOPs you can get it out by specifying it on the import node.

There are some great ideas posted here, which may seem tricky to wrap your head around, I am just trying to help explain “why” its so tricky.
The best solution is probably to not simulate the color volumes at all and use something like tricecold suggested.

Hi tricecold!

I did everything you told me!!

I already have the particles cached with the color advected by the volume

However… Didnt get it to work the sample color in the shader!!!

I have been on it for days and…. nothing!!

great, now you can follow this forum

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&p=121161&sid=81aef4ab6769acafc88af4b872053485 [sidefx.com]

and this one

http://forums.odforce.net/topic/13899-vex-volume-procedural/ [forums.odforce.net]

to get more of an idea how this might work.

THAAANK YOU!!!!