i made a simple smoke simulation in embergen and exported the sequence as VDB files.
Now i`d like to fade out the smoke stream at the beginning and the end of it.
Tried it with a gradient ramp, but i only get a hard cut ( see attached screenshots where i marked the position on the gradient and the corresponding position on the volumetric.
Also this gradient is only mapped horitontally and not following the curvature / path of the volume grid.
Also tried to draw in the opacity diagramm , but this had no effect at all.
any help is really appreciated on this, thx.
Robin
This is because your Gradient Ramp’s mapping is set to Explicit Map Channel, something that generally isn’t exported from simulations, unless set up to do so (at least in Phoenix). Here’s how you do it in PhoenixFD. This method will be a bit of extra work, since you would need to play a lot around with how the Gradient Ramp gets projected so as to affect only the start/end of the smoke sim.
The easiest way I could think of is to use a VRayDistanceTex for the Gradient Ramp’s mapping. This way, you’ll have control over where the fading is happening. The problem is that if the smoke is, f.e, moving, you will need to animate the distance tex’s geo as well.
The diagram works when you’re basing the Smoke opacity on a certain channel (Smoke, Fuel, Temperature, etc.), and that curve will be applied, so to speak, as a multiplier on that channel. Sorry to say, we don’t we have a node analogous to the HairInfoTex (where you can map something across/along a strand) for simulations.
