This is a tricky one - decals and displacement

jordank95

I have a snowy terrain that has displacement and character footprint interaction as they move through the snow. I need tire marks to show as well and Im unsure of the best approach here. Using decals doesn't work well because the normal map has issues over tessellated snowy terrain. Using meshes wouldnt work either because the tire track meshes would need to be below the surface of the snow to look correct. What are my options here?

poopipe

there are quite a few well estabished methods - particularly in unreal.  have a google. 

how you implement it depends a lot on scale and whether you need persistence or not

jordank95

@poopipe spent a good amount of time googling. I listed the methods I came across (and have used in the past myself) in my post, but I listed why they arent working for my specific situation...which has all lead me to post here, hah. Scale is first person. This would be something used in multiple places across a snow map. 

okidoki

Haven't used or done anything like this myself yet .. but as i just now  re-searched (a  little) some snow shader setups where the actual player seems "to paint" on some "track" map.. couldn't the tire track "simple" be added to this already ? Or the problem might be somehow more complex as i understood this right now (because you speak of normal map but as far as i yet have seen this those shaders uses an upward displacement ?). 

poopipe

projected decals 'should' work fine with tesselation (haven't tried in unreal) - this is what we do for footsteps etc. in most of our games

perhaps it's worth posting some images illustrating the problem - could just be some maths (can't check because I've uninstalled unreal)

you could try writing into a virtual texture and using that data to modify your various materials - this would give you persistence but could end up being quite costly to do the writing if there are many things making footsteps