Is animating the RGB of smoke possible?

[BeneZ]

Hello,

here my next question
I was thinking to change the color of smoke, after it is emitted (and not "born" anything new). Ideally also driven by UV-texture.

I have seen the tutorial about changing smoke color (https://docs.chaosgroup.com/display/...+RGB+Workflows).
In chapter 5 there is a description with a Vray Distance Texture. But this is - as far as I understand - not using originals Objects UV-placement, but a RGB of a new object.

There is now a new UVW Texture, which I still did not learn in detail
(just waiting for the announced "updated" tutorial on this for phoenix 4.10. And also for the "thin smoke tutorial", which was in the new phoenix4 demo).

But one short general question I currently have is, could I then change color with UVW in a way like an image sequence would work?
Do the "voxels" store UV position from their birth and can update therefore the RGB?
Or is the smoke after it is emitted not more controlled by the UVWtexture?
(not asking for how to do it in detail, I will wait for the tutorials...)

Thanks

[Svetlin.Nikolov]

Yup, that's it - the new TexUVW is the way to go.

Voxels and particles store the UVW at the moment of their birth, and it could remain unchanged forever, or it might get updated over time with new values depending on the TexUVW options under the Dynamics rollout.

Cheers!

[coolhand78]

Can someone elaborate on exactly how to do this? ie. animate the change in smoke colour?
thanks

[georgi.zhekov]

Well it depends on how you want to animate the color change?

1. You can animate the RGB color or if you use a texture for the RGB channel you can do this during the simulation.
2. If you're using Phoenix 4 - you can simulate first with a certain RGB texture just like the tutorial mentioned in the first post. Just make sure to turn on the TexUVW channel in the output rollout before running the sim. Then after the sim is done you can set the Smoke color in the Volumetric options to be based on a Texture. In the texture slot you can plug a Mix texture. For one of its inputs plug a Phoenix Grid Texture, that reads the RGB channel from the simulator and for the second input plug another texture (Noise texture for example) - just make sure this is set to Explicit mapping so it can read the TexUVW data. Then using the Mix texture's Mix amount you can control which texture shows up. You can animate this value.
3. You can check our Template scene for Animating the smoke color by age - https://docs.chaosgroup.com/display/...mokecolorbyage

Cheers!

[BeneZ]

Hi georgi.zhekov
I tested again the volumetric smoke color and did not succeed:

- When I feed in exactly the same texture, that created the RGB-channel into the "Smoke color", then I don't get the UVWtex
I tried everything, but mainly
Modulate activated & Texture (instead RGB).
There is no difference when I toggle "modulate" (which is the button to load the texUVW position as far as I know)
Is there anything else to do? Is it a special mapping channel?

- When I create a PhoenixFDTexmap (oder Gridmap) node and try to connect the simulator (with Pick) nothing happens.
3dsMax nearly freezes until I press escape.
Is there also a hidden trick?

(otherwise I need to run a test with a simple fresh scene)

Thanks

[Svetlin.Nikolov]

Hi georgi.zhekov
There is no difference when I toggle "modulate" (which is the button to load the texUVW position as far as I know)

Let me just quickly drop in on this - this is not correct. TexUVW works both when Based On set to Texture, or when Modulate by texture is checked. Modulate means "multiply the Based On choice by a texture", so this way you can get based on smoke, modulated by a noise, etc.

[BeneZ]

So I have prepared a very simple example scene, where I maybe am doing something wrong.
I have sent it to you now. There is screenshot and PHX cache already in, so you could just jump in.

Please have a look and let me know your mysterious secret
THX

[georgi.zhekov]

We can't find the scene in our system for some reason - can you give us the ticket number or may be you sent it to some other mail address different from the support one?

Thanks!

[BeneZ]

You are right, sorry, I had a typo in the emailaddress
Now I have sent correctly to support@chaosgroup.com
Thanks
ticket number is: 300-506-4933 

[georgi.zhekov]

Got the scene - we'll let you know once we have more info.

Thanks!

[georgi.zhekov]

Your scene seems to be working correctly.

It's just that if you use the same texture for the RGB simulation channel and then for recoloring using the TexUVW channel you will get similar results.

The idea behind the TexUVW channel is that you can use another texture and when your smoke color is set to Texture or you use the modulate option - the texture will flow with the smoke correctly, instead of just staying in one place.
This way you don't have to resimulate again just to change the color of your smoke.

In your scene if you plug a checker or a noise texture in the texture slot you can notice the texture will flow with the smoke.

Hope this helps!

Cheers!

[BeneZ]

Hello,
georgi.zhekov
unfortunatley it does not help:
I wonder if we are talking about the same, because the results are completely different and this is what I tried to achieve since some days.

To make it more visible I have here attached another render (changed the setting without turbulence and used a clearer picture for comparison).

I thought the sense of TexUVW is, that I can exchange anytime the texture and get the same result, like it was rendered in the beginning with that texture.
But it looks not the same.

EDIT: wait there is was wrong setting, I will update. But it will stay the same problem...

[BeneZ]

georgi.zhekov So here the correct comparison: It's definetely not the same
Original RGB looks more washed out and the same map used as "texture" looks much more sharp and colorful.
(no difference for texture, if "modulate" is on or off)

[BeneZ]

Just in case: I have put also this file and texture into the exchange link

[Svetlin.Nikolov]

Okay, check it out, I think we've mentioned this at least twice, so I'll try to put it differently

"Modulate" does not activate TexUVW. It's active as long as you have TexUVW in the loaded cache.