Tricky gradient mapping? Changing color of complicated textures

AlexandrL

Hi guys! :)

Found this one on artstation: https://www.artstation.com/artwork/o2Wgam

I know there was some gradient palette mapping technique back in the days for pixel art games.

That video explain that a bit: https://www.youtube.com/watch?v=Cx9Xu_54GOU

But im not sure how it was maded by Pawel Kostecki.

Maybe some one can show some more examples and explain this?

Fabi_G

Hi! The example from artstation looks like a linear interpolation, blending two inputs by grayscale mask. Check out Lerp/UE documentation. On a second look, I was mistaken, seems to involve gradient mapping, not just a simple lerp, oops :P

Only watched a snipped of the video. In Unreal Engine you can do this by creating a gradient (curve asset), assign it to a curve atlas, to then use it inside a material to color a grayscale input by the gradient. Check out Curve Atlases in UE. You could then lerp the gradient mapped result with the original texture based on a grayscale mask?

poopipe

You don't lerp. You index into the array using the grayscale value of the pixel.

If the pixel has a value of 0.4 it uses the color 40% along the array

You can take this sort of thing quite a long way if you move out of RGB space.

Eg. In hsv space you can remap or replace just the hue component of a color image .

I've built systems based on this idea to support player customisation a couple of times now - when arranged right it's pretty efficient and as a bonus is low effort in terms of authoring.

Noors

Yeah that's my guess aswell. You can have a look a this video, he's setting indexes for a normal maps array instead of colors but it's the same principle

https://youtu.be/avZ26yW2KBw?list=PL78XDi0TS4lEBWa2Hpzg2SRC5njCcKydl&t=1047

Eric Chadwick

Another good example, nicely explained

https://polycount.com/discussion/174377/witcher-3-blood-and-wine-architectural-material/p1

poopipe

https://polycount.com/discussion/comment/2778255#Comment_2778255

that's quite neat - I mucked around with something similar that made use of texture arrays a little while back but abandoned it because there simply wasn't time to go back and add vertex color/textures to the meshes involved.

Should work brilliantly if you plan your work out ahead of time though

AlexandrL

Thank you guys :) Im basically was a bit confused about lerp which was mentioned on artstation, and was trying to figured out where and how the lerp might help.