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Is there a reason Decals are two-sided?

Discussion in 'High Definition Render Pipeline' started by dgoyette, Oct 31, 2019.

  1. dgoyette

    dgoyette

    Joined:
    Jul 1, 2016
    Posts:
    4,193
    I have some decal prefabs I use to put stuff on walls. I use them rarely enough that I always forget whether I set things up for the prefab's "forward" direction to face into the surface or out of the surface. For some decals, it's really obvious when I have it flipped 180', but for other decals it's more subtle. It's always the case that having the decal flipped 180' results in it looking wrong, and eventually I figure it out and flip it.

    My question is: is there a strong reason why decals were made to be two-sided, such that if it's flipped 180' it will render, but with inverted normals? It seems it would be much more convenient if the decal only rendered in one orientation, so I don't have to judge whether I've got it reversed or not. I don't see an option to turn off this two-sidedness in the material or the projector.
     
  2. Agoxandr

    Agoxandr

    Joined:
    Aug 16, 2014
    Posts:
    49
    Where decals are projected is usually limited by an angle. As far as I know HDRP decals are not limited by an angle. It's not implemented.
     
  3. dgoyette

    dgoyette

    Joined:
    Jul 1, 2016
    Posts:
    4,193
    I agree that there currently isn't an angle limit with HDRP decals. (FWIW, one of the devs recently mentioned that this was something they're hoping to add in the future.) I'm trying to decide whether this is just an angle-limit issue, as you mention, or something more weird that could be resolved without an angle limit. It seems like it would be ideal if the material could be set to not be two-sided, though I don't know if it really is two-sided in the normal sense, or whether it's something else.
     
  4. qsp18

    qsp18

    Joined:
    Apr 27, 2020
    Posts:
    1
    In unity 2021 its now implemented (i am using 2021.3.14f)