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Question What output type for smoke/steam?

Discussion in 'Visual Effect Graph' started by dgoyette, Jul 3, 2020.

  1. dgoyette

    dgoyette

    Joined:
    Jul 1, 2016
    Posts:
    4,003
    I'm trying to make a fairly simple effect, just some steam coming out of a pipe:

    upload_2020-7-3_1-4-29.png

    Initially I "Output Particle Quad", but found that the downside to that output is that the steam is full-color even in low-light situations, which looks pretty silly. Here's that same steam, but with the lights turned off:

    upload_2020-7-3_1-6-3.png

    So I figured I could just use "Output Lit Particle Quad". But now the problem is, unless the steam is receiving direct light, it appears to be black. Here's what that same steam looks like if I move the camera down one meter:

    upload_2020-7-3_1-7-2.png

    This looks really bad when moving up and down, without changing anything in the VFX:

    Steam.gif

    So, either I essentially have emissive steam with the Unlit output, or I have this weird behavior where the steam turns black unless a light is hitting the steam directly.

    Do I have other options?
     
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  2. JulienF_Unity

    JulienF_Unity

    Unity Technologies

    Joined:
    Dec 17, 2015
    Posts:
    284
    Hi, to give more sense of volume to your smoke and less uniform reaction to light, you can use normal bending option in output inspector to get your quads react to light more like a bent plane (and then tweak the bending factor). You can possibly add a normal map too.

    However lit quad output is not free (especially when there's lot of overdraw). To optimize this, you can use simple lit mode and toggle on/off lighting options you need. You also can use half res rendering on this particular system. All this is also accessible from the output inspector.

    I believe we have some smoke examples in our samples (spaceship demo and a bonfire in official samples)

    We will be working on dedicated lit models for smoke in the future too.
     
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  3. dgoyette

    dgoyette

    Joined:
    Jul 1, 2016
    Posts:
    4,003
    Oh, wow. The big thing you just taught me is that there's stuff in the inspector when using VFX graph... :

    upload_2020-7-3_10-20-19.png

    I guess I just assumed everything in VFX was self-contained in the one editor window, and I actually had that window floating above the inspector, so I never noticed there were further options. Thanks for pointing that out. I wonder if there's a way to make that more obvious, or if I just had bad luck with my workflow that I didn't notice it.
     
  4. JulienF_Unity

    JulienF_Unity

    Unity Technologies

    Joined:
    Dec 17, 2015
    Posts:
    284
    All nodes in VFX Graph have potential options in the inspector. But yes, we are aware there is a discoverability issue here and are working on a solution. You're not the only one to have never noticed the inspector...
     
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