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Question Why do my additive materials make the mesh glow when color value is 0?

Discussion in 'High Definition Render Pipeline' started by PolarbombVFX, Jan 26, 2024.

  1. PolarbombVFX

    PolarbombVFX

    Joined:
    Aug 22, 2023
    Posts:
    14
    Hello!

    I ran into a problem with how additive transparent materials were rendering in my version of Unity - 2023.1.13f1

    The problem looks like this with a black and white texture:
    upload_2024-1-26_13-45-25.png

    It's not because the texture has color values in it covering the entire square.
    If I multiply it's color with 0 I still have the glowing square.
    upload_2024-1-26_13-47-11.png

    I have this very basic test shader in Shader Graph that looks like this:
    upload_2024-1-26_13-43-48.png

    The VFX Graph example is using its standard shader so I don't think it's me doing anything funny with the shader.

    If I turn off Bloom in the post process the problem goes away. But I also don't get bloom, which is a problem.
    I can increase the threshold for the bloom but as more transparent surfaces get stacked on eachother they overcome that threshold at some point, so also not an option.
    Not using fog has or setting the material to not receive fog doesn't do anything.

    Setting the alpha of the material or in VFX Graph makes it disappear, which isn't how it should work. I shouldn't have to turn down both color values and alpha value to fade an additive particle away.

    Any ideas what could be causing this?
     
  2. PolarbombVFX

    PolarbombVFX

    Joined:
    Aug 22, 2023
    Posts:
    14
    Why do VFX Graph particles with its standard shader set to additive start blooming the entire quad of the particle even if the texture is black? It really makes no sense.

    I've tried turning pretty much everything off in post process and rendering except transparent objects and bloom and the issue is still there.

    The image above with glowing particles are a couple of particles stacked ontop of each other to make the issue more visible.

    To test this:
    Make sure post process and bloom is on.

    1- Make new VFX Graph
    2- Make sure to output "Output Particle Quad" and set the rendering to Additive.
    3- You can use a black texture or a white texture where you set the color to black through VFX Graph
    4- Stack a couple of particles on top of eachother and notice how the entire particle blooms.