Spline Decals?

[KristyDoe]

This is the latest version of the tool i created. If it helps any1. You can use it with multiple St Meshes and/or decals. You may have to move the spline points to get the result you need. Try it. I helps you good. It doesn't

I tried importing this into my project file, and it never appears.

[Manoel.Neto]

DecalActors use depth-based projections. Which means the world position of the pixels inside the decal area are used to calculate the UVs for the decal texture. Using the same approach for a spline instead of a box is not feasible, because you'd have to convert world coordinates into spline coordinates and there's no analytical algorithm that can do that, so it would be a messy and expensive shader full of iterations that may or may not work.

So the only practical way is to lay over geometry along the spline and try to match it to whatever is underneath it. That's what CryEngine does, BTW.

[Deathrey]

So the only practical way is to lay over geometry along the spline and try to match it to whatever is underneath it. That's what CryEngine does, BTW.

Myth about fancy spline projected decals had been around as long as this thread.
While there are ways to project UVs from arbitrary geo into the world, they all more or less revolve around splitting everything up into prisms and having an insane per fragment cost at grazing angles.

I think I did already post somewhere here, that the essence of this thread is request expand functionality of landscape splines to produce a proper mesh, that is a result of intersecting splinemesh and landscape LOD0(or optionally, scene geometry LOD0).

[Maximum-Dev]

Even if we have proper spline decals, landscape tessellation would still be a problem, since decals don't support displacement, decal would be project on the underneath deformations making it look very wrong. Pretty far from hoping to see all this situation improve by Epic.

[Deathrey]

Even if we have proper spline decals, landscape tessellation would still be a problem, since decals don't support displacement, decal would be project on the underneath deformations making it look very wrong. Pretty far from hoping to see all this situation improve by Epic.

Not exactly the case. You are supposed to paint a layer, that has no displacement under spline decal. Then decal itself can be tessellated and positively displaced.

But yeah, that is all a terrible raindance, when compared to freedom one has with decals when working with PVT and with all that in mind, whole landscape system in UE4 is a bit dated by modern standards and slight improvements to landscape splines aren't going to upgrade it noticeably.

[muchcharles]

Myth about fancy spline projected decals had been around as long as this thread.
While there are ways to project UVs from arbitrary geo into the world, they all more or less revolve around splitting everything up into prisms and having an insane per fragment cost at grazing angles.

I think I did already post somewhere here, that the essence of this thread is request expand functionality of landscape splines to produce a proper mesh, that is a result of intersecting splinemesh and landscape LOD0(or optionally, scene geometry LOD0).

Now that they are starting to add virtual texturing (lightmaps only in 4.21), if they add it to landscapes in a dynamic way you could do expensive decal projection operations just on a local area, with cost divided over frames:

https://www.gdcvault.com/play/102176...e-Rendering-in
https://80.lv/articles/landscape-and...con-wildlands/

Maybe precompute all of the ones at lower mips up to some storage budget, then draw in the nearby higher mips dynamically.

[Manoel.Neto]

Now that they are starting to add virtual texturing (lightmaps only in 4.21), if they add it to landscapes in a dynamic way you could do expensive decal projection operations just on a local area, with cost divided over frames:

https://www.gdcvault.com/play/102176...e-Rendering-in
https://80.lv/articles/landscape-and...con-wildlands/

Maybe precompute all of the ones at lower mips up to some storage budget, then draw in the nearby higher mips dynamically.

With virtual texturing all you'd have to do is render the spline geometry into the landscape VT as a render target. That's how it works in Far Cry 4/5, where they can use a large amount of decals because they cost nothing after they get "baked" the first frame they appear. If Epic is working on modernizing the landscape, using virtual textures is the way to go, since it also eliminates the cost of blending terrain layers at run-time.

[Staazvaind]

holy **** !

coming from cryengine this is a must-have for any engine nowadays.
cant even believe whats been happening here:
maximum-dev had enough supporters on this matter and the ticket gets deleted ???

this one thread really makes me rethink going back to CE or lumberyard.

i have always asked myself why so many devs place decals manually over maps
to crack up roads... now i know... jesus

[jojo8026]

holy **** !

coming from cryengine this is a must-have for any engine nowadays.
cant even believe whats been happening here:
maximum-dev had enough supporters on this matter and the ticket gets deleted ???

this one thread really makes me rethink going back to CE or lumberyard.

i have always asked myself why so many devs place decals manually over maps
to crack up roads... now i know... jesus

Good Job Epic you officially drove a potential customer away because the engine isn't up to modern standards

[KristofMorva]

Good Job Epic you officially drove a potential customer away because the engine isn't up to modern standards

Even worse, it's not even a modern feature :'D

[jojo8026]

Even worse, it's not even a modern feature :'D

I know right lol

[Jörmongandr]

Spline decals would be super helpful for so many developers. I've been working on two separate games and I've needed this but I haven't had the time or talent to do it myself. I don't even know where to start on something like that. It would be a big boost to everyone else that is the same situation. It's one of those features that not that many people would think about and ask for, but if presented would become wildly popular and used all over the place.

[ElegantSquid]

I didnt see this method mentioned, so maybe ill chime in. you could potentially use mesh spline and use materials to project down onto the below surface similar to a decal. Ryan Bruck's even made a node from this, as mentioned in his bullet train demo talk.

[Vertex Soup]

Shameless bump after rereading whole thread again (maybe like 5th time). I'm working on large scale city scene and roads are major issue. I went though all posts in forums that touch on road topic and none of solutions works good enough to be usable on larger scale without crazy amount of manual labor that totally kills any creative soul and makes them hate their job. I'm expecting Epic to implement better decal handling with upcoming megatexture feature as that would make use of decals on larger scale nearly free. I would welcome tech similar to FarCry decal pipeline as it is just logical way of doing things.
I hope that one day in not that distant feature we can have this ISSUE solved and Unreal Engine will again become tool that brings you smile and joy not frustration and insanity doing trivial daily game dev tasks.

And cheers to everyone on staff who even bother to read my comment, that's a good start!

[Staazvaind]

Shameless bump after rereading whole thread again (maybe like 5th time). I'm working on large scale city scene and roads are major issue. I went though all posts in forums that touch on road topic and none of solutions works good enough to be usable on larger scale without crazy amount of manual labor that totally kills any creative soul and makes them hate their job. I'm expecting Epic to implement better decal handling with upcoming megatexture feature as that would make use of decals on larger scale nearly free. I would welcome tech similar to FarCry decal pipeline as it is just logical way of doing things.
I hope that one day in not that distant feature we can have this ISSUE solved and Unreal Engine will again become tool that brings you smile and joy not frustration and insanity doing trivial daily game dev tasks.

And cheers to everyone on staff who even bother to read my comment, that's a good start!

not shameless at all ! (y)