Additive Alpha Blend in Unity? {{ShaderForge}}

[colossaladvent]

@CellarPhantom Ah gotcha. That makes sense because it does disappear if the RGB is a value of black.
@DedRed Ok I’ll try that out! Thanks.

[Torbach]

popcorn wiki has a comprehensive visual to explain but I’ll elaborate
http://wiki.popcornfx.com/index.php/Particle_tutorial_smoke#Setting_up_the_billboard_renderer

note alpha channel acts like a mask: as @Sirhaian called AddMul

if you network like @DedRed

Vertex.Alpha * source.RGB = emission

you re-create [SrcAlpha] [OneMinusSrcAlpha] and cannot use particle system vertex.alpha to lerp styles.
You still get addBlend according to alpha channel but imo it’s not the same

It comes down to preference

• alpha acting like opacity …? or strictly controlling ‘Additivity’

One OneMinusSrcAlpha power imo comes from being able to lerp alpha <-> additive and in shaderforge the nodes would be

• vertex.RGB * texture.RGB = emission
• vertex.Alpha * texture.Alpha = opacity
  

so as @CellarPhantom pointed out you can’t use Alpha for opacity; the textures opacity is controlled by ‘fading out’ both Color and Alpha

to visualize you can imagine photoshop…

1. Texture.RGB is a dodge channel
2. Texture.Alpha [inverted] is a multiply channel

then you can mix-n-match styles: alphy, semi-additive, fully additive, /w full transparency etc…

whew, is this more clear?

[q7204k]

Sorry for necroposting, but I’m trying to create this shader and have an odd bug - the texture is stretched out (?):

monosnap.com

No idea why and how to fix it (but several textures are fine). I use Unity 5.6 and Shader Forge 1.38

[Torbach]

Adobe Photoshop PNG will compress RGB like that and not save an Alpha channel for “blendAdd”

use Super PNG
http://www.fnordware.com/superpng/

• you have to make a proper alpha channel
• your RGB (texture) must be on a black background

[KaguKin]

Hey, sorry for bringing this back from the dead, but i’ve been staring at this thread all day trying to wrap my head around it.

I’ve got some help from a friend of mine and made a shader like this using code, but it won’t work with hdrp annoyingly, so I’m currently trying to recreate it in either shadergraph or amplify, but I just can’t seem to get it right.

Has anyone had any success making a AddBlend shader like this using Shadergraph or Ammplify?

((Alternatively knows how to get custom shaders to work with hdrp properly))

[JoanP]

Here is how I see it in Shadergraph

Difference on a Bright Surface Beetween ADD and BlendADD

[KaguKin]

Looks really interesting, i’ll try that out for sure.
I’d love for regular written shaders to be used again tho, as I’ve got a couple ones i wanna reuse, but don’t really have the experience with shadergraph to recreate just yet

[Torbach]

helps to know ; prevent miscommunication +help you find what you want

BLEND-ADD (as Julian Love called it in GDC 2013) is …

pre-multiplied Alpha blending

• Microsoft Document
• Nvidia Document

since ‘Alpha blending’

= (Color * Alpha) + (background * [1 - Alpha])

you can toss out that bold instruction (Color * Alpha) in your engine because ‘pre-multiply’ obviously implies the work was already done — you now save the computer instruction overhead

shaderGraph (many tools that offer this in a pulldown or in a default material setting) use this nomenclature : well… obviously because it is technical tools created by Tech companies

this is basics
Texture.RGBA * TINT.RGBA (or Vertex.RGBA)
just split the Alpha out when done
choose blend and the pre-mult operation

JoanP what does Red channel HDR * Alpha do? confused me

[JoanP]

Well you can use RGBA, i’m doing this for the background of a texture when you import one as black or transparent from PS.