(Fixed) [HOU-1371] Simple Smoke Opacity slider in the Volume Grid shader doesn't do anything

[blented]

Assign a Volume Grid shader to a volume, render
Turn Simple Smoke Opacity to .01, render again

I'd expect the smoke to be thinner but it renders the same. This used to control the smoke density / opacity but seems like it's no longer hooked up.

Thanks!

Windows 10
Houdini 17.5.425
VRay 17.5.293_6c36393_5752

[Gosho.Genchev]

Hey, Grant,

long story short - the ramp brought up by the Opacity button below is used, and the mapping is based on the Fields -> Smoke -> Opacity field specified. We'll add a toggle allowing to switch between Simple Smoke Opacity and the Opacity ramp - I hope this will work for you.

All the best!

[LeoYfver]

this is a gui nightmare we had in maya also. Could this be greyed out and only enabled when field is active. Or preferably have it as a multiplier, but i guess thats a core thing

[Gosho.Genchev]

this is a gui nightmare we had in maya also.

We tried really hard to get away from the channel mapping workflow. Is there anything else in the GUI of the shader you guys dislike besides the dysfunctional "Simple Smoke Opacity" ?

Or preferably have it as a multiplier

This can't happen, sadly.

Could this be greyed out and only enabled when field is active.

You mean the Simple Smoke Opacity option? It too uses the field ... it's basically a short-hand option to scale the opacity. If no Smoke Opacity volume is specified, neither the ramp, nor the Simple Smoke Opacity will work.

I really don't want to bore you guys with details as to how things are handled in the background - those "Based on" options you see in the Volume Grid in Maya and Max are still used - there's no way around that. We hid them, and hard-coded them to certain indexes in the cache file. When you hit render, we look up the Fields tab, find the volumes by name, and place them in the correct index position - this is done so you don't have to handle it yourself, as in Maya/Max.


The plan is to leave "Simple Smoke Opacity" as default, with a checkbox used to select whether "Simple Smoke Opacity" or the ramp is used.

[LeoYfver]

makes sense. If i have any suggestions i will tell you. thanks for the response!

Regards Alexis

[blented]

"The plan is to leave "Simple Smoke Opacity" as default, with a checkbox used to select whether "Simple Smoke Opacity" or the ramp is used."

So will Simple Smoke Opacity work and just be on a toggle? I'd say 90% of the time that's all we're after is just the multiplier.

On a positive note, the checkbox to scale for scene units is much appreciated

[Gosho.Genchev]

Yes, it will work.

All the best!

[blented]

Great news Gosho, let us know when it's hooked back up please

[Gosho.Genchev]

blented , the change has been in the nightly builds for a few days now. We've added a toggle "Use Opacity Ramp" parameter in the Smoke roll-out.

I've been trying to come up with a way to update the changelog so it doesn't rely on me trying to track everything manually. I hope very soon we'd be able to update the changelog every day.

All the best!

[blented]

Amazing, thanks Gosho