How can I achieve this faded concrete paint effect with vertex blending?

TBAXTER

Hello Polycount, I have been looking for a solution to this for a little while now, basically i need to find a way to achieve this faded paint on concrete effect as shown in the image above with vertex blending.

I know the typical approach for texture blending is to use a Height-map as a Blend-mask, but since the concrete height texture doesn't have much height variation it doesn't really work & vertex blending on its own is too soft and low res by default.

What are my possible options here?

thanks.

Benjammin

Assuming you're talking about Unreal - Same principle applies, but you'd multiply your vert color with a new texture map that has that kind of noise pattern. You may need to pass the result through a power node to increase contrast.

Eric Chadwick

Yup. Some visual examples: https://polycount.com/discussion/174377/witcher-3-blood-and-wine-architectural-material

poopipe

I often prefer this approach over multiplying a noise over my vertex color gradient
This isn't "better" - its just different 

The main benefit to me is that it centers the noise around the mid point of your gradient rather than only eating into the higher values and also gives you more contrast. 
(example in designer but the maths will translate directly to unreal cos i did them all by hand)





I've used a simple contrast function to manipulate the incoming gradient (vertex color in your case) which allows me to tighten up the 'edge' . 
This is quite a lot cheaper than a pow() operation and in many cases offers more control but it is linear and will break more readily than using a curve (eg pow)

this input and a cloud noise  

contrast set to 3 gets you this output :

contrast set to 1 gets you this:

Eric Chadwick

Wow, thanks for sharing. I remember having to avoid POW when writing shaders for a mobile game, just using ADD/SUB/MULT but my blends ended up being much more fiddly and hard to finesse. Nice technique.

poopipe

tbh outside of Switch you probably don't have to worry at all about using pow() these days but it's worth second guessing whether you need to or not  just in case you feel the need for a pat on the head from a render programmer. 

you could certainly insert a curve in place of the contrast function if that hit your visual target better - the main thing really is the remap -> add vs multiply

Eric Chadwick

iPhone and Android perf limits were definitely a thing when I was working on it, back in 2016.

poopipe

Eric, I'm sad to say that 2016 isn't 'these days' anymore

Eric Chadwick

Haha, did I say these days?! I haven't been in game dev anymore, for quite a while now.