How's this technique called? And how to achieve it...

Pep_mepla

Hello there!

I was making an environment when I came up with this problem. I want to have something very similar to this (Screenshot from Kirby's Forgotten Land) in which the terrain has a tilable grass texture, but when it reaches the edge, transitions to a similar texture, but with some different details like leaves. I'm pretty sure I've seen better examples somewhere, but I can't find them right now.

I would really appreciate it if anybody could tell me how it is called so I can google for some tutorials, or broadly how would you tackle this thing.

Thanks a lot!

dimwalker

Those could be decals - in simplest form just a plane with transparent texture floating above other geometry.

Joopson

You could also do something similar with an up-vector shader, similar to how snow can be faked (i.e. only on parts of the mesh that face upward)

Klunk

could be a 2 texture alpha blend, or a vertex color alpha blend for 2 textures....


vertex alpha (left) gives a smooth gradient blend dependent on vertex density, texture alpha blending can give much more variation in the blending and is independent of the vertex density

Kligan

On a shader level you could probably do something like this with projection. Triplanar mapping in unreal, for example. 
From top you project grass texture. And from the side - the leafy patches. They would blend at the smooth corners.

okidoki

Maybe just some clever usage of the tiled areas with the mixing parts using some part of the tile and and overlapping (but additional convex) geometry with a ziggyzagged alpha at the borders...

Alex_J

are we certain there is opacity involved?

It's kinda low res image but looks to me like there was just a dark background, leaves painted on top of that, and the geometry is a rectangle just unfolded so that it would fit into image like klunk showed.

poopipe

I presume this is on Switch so they've not exactly got gpu cycles to spare. triplanar projection and alpha are unnecessarily expensive ways to solve the problem so If klunk/alex  aren't correct I would be very surprised

Simply offsetting the UVs used to sample the grass relative to object position can take care of any tiling  issues without the artefacting associated with a simple worldspace projection.
Below is a simple unreal example of the principle 
(A different texture is used in the 3d shot to better demonstrate the effect)

Klunk

another alternative could be 2 textures that match at the seam like a "traditional" tiling terminator  

Eric Chadwick

That’s what I think is going on here. No fancy shader, just highly performant flat textures in trim sheet layout. 

Here’s an example for a Wii game, see the section “Performance & Memory”
https://ericchadwick.com/img/world_of_zoo.html

poopipe

The only reasons I think it needs anything more complex is the high frequency grass stuff -  you'd need fairly large textures to get the information in and it would be tricky (not impossible, but time consuming) to avoid seams at any point where the geometry goes off-grid 

Either would work out fine though I'm sure

pior

I think it's fair to say that after so many helpful replies, it's up to the OP to come back to the thread and make the effort to show more screenshots and videos of the part in question from the Kirby game ...

Eric Chadwick

Some clearer reference, green level starts about 25 minutes in.
https://www.youtube.com/watch?v=iwH49iOMxFY

Pep_mepla

Thanks a lot for your answers, they were very helpful!

I decided to take the tilable texture and mask it with another texture that resembles blades of grass, I think it gives a nice effect. It isnt perfect but does the trick. I'm just testing the uv's on blender for now, but I like it so far.

Seriously thanks! I was at a loss, but with your help was able to see the light

Alex_J

nice i like that look a lot. i think i like it more than the kirby example, however i think the really chonky bevel they used is more attractive.

Klunk

another alternative given your example could an overlap with an alpha


then you can vertex shade the top verts of the mud strip faking an "ambient occlusion" also add some depth