Smooth Pyro Dissolve

[thomas67]

This is roughly what I'm trying to create, only with a smoother transition. In the example, the smoke is being generated by an animated gradient ramp, and the opacity of the text geometry is controlled with another ramp at render time.

With Houdini, I want to utilize another workflow, I'm importing the whole text in my pyro sim as a fog vdb. But I don't want the whole text to be affected at once, I want to gradually dissolve the text from left to right, similar to the shown example.

  1.  (How) Can I drive the 'activeness' of the pyro solver with an attribute?
  2.  How can I make my density text vdb as opaque, as if it would be an sdf?

Thank you in advance!

[nuki]

you could use a scalar field (eg. with an animated 0-1 ramp) and multiply turbulence/vel with

Edited March 14, 2020 by nuki

[Atom]

One way is to control the temperature field. In this setup, two animation control the result . One is an animated Clip node, that removes the density from the source while the other is an attribute transfer node that grabs the newly transferred color and supplies it as temperature to the remaining clipped surface. The blend width of the attribute transfer is used to precede the clip, increasing the temperature ahead of it. Once the temperature is above zero, the smoke starts to rise.

And the smoke only.

 

ap_up_in_smoke_031420.hiplc

Edited March 14, 2020 by Atom

[thomas67]

Thank you very much Atom!

[thomas67]

 

On 14.3.2020 at 9:07 PM, nuki said:

you could use a scalar field (eg. with an animated 0-1 ramp) and multiply turbulence/vel with

This sounds good, I tried controlling the turbulence and dissipation with it, but I have no clue how to use a scalarfield, I tried mapping an attribute to it, which I rasterized in sop and connected to  the dopnet, but it doesn't work. Would it be possible that you show me the proper way? 

 

 

Edited March 17, 2020 by thomas67