Thread by @exppad

Having a lot of fun reproducing @OskSta 's #Townscaper in #unity3d, very instructive exercise!
⬇️ Details in the thread bellow 1/10

Townscapper is based on #MarchingCubes, the traditional algorithm for converting voxel data to polygonal mesh (see also #DualContouring) 🧊
⬇️ We will apply it on a less usual grid though 2/10

Non regular grid generation based on hexagonal tiles with randomly removed edges.
Subdividing ensures that faces are all squares
➡️required to apply marching cubes! 3/10

Marching cubes is already kind of a #DictionaryBased algorithm. Its original "atoms" (or "modules") are very simple 1-4 triangles meshlets.
⬇️ But we can change these atoms 4/10

Custom marching cube atoms are imported from #Blender3D and labeled with the cases of empty/full neighboring #voxels they fit.
⬇️ Nevertheless they cannot be used as is! 5/10

Atoms must be deformed to fit our irregular cells.
We know where to move a few key poitns points based on the grid mesh
➡️use case for cage-based mesh deformation
Many algorithms exist, some of them here: github.com/superboubek/QM… 6/10
(Yes, it's a paper from my research team 😇)

We can use Spherical Mean Value Coordinates because cage faces are planar for sure.
Running real time but could be improved using #ParallelFor jobs. 7/10

For an easy #ProceduralGeneration in #Unity3D, we need a #DataStructure to represent meshes that is more flexible than mesh.vertices[] and mesh.triangles[].
For instance how to quickly find all the faces connected to a vertex? 8/10

I reproduced a basic version of #Blender3D 's #BMesh structure in #Unity3D. A real pleasure to work with!
More about BMesh: wiki.blender.org/wiki/Source/Mo… 9/10

📚 Some other references 📚
Oskar's talk at IndiCade Europe 2019 for technical insights
@OskSta's tweets for inspiration
More about hexagons: redblobgames.com/grids/hexagons/
Can't wait to play with #WaveFunctionCollapse now! 🤩

10/10

This part is now available!

https://twitter.com/exppad/status/1263605678746284033

:)