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Posted by imagiro 1/8/2026

I'm making a game engine based on dynamic signed distance fields (SDFs) [video](www.youtube.com)
451 points | 78 comments
turtledragonfly 1/11/2026|
This is super cool, and I like the no-nonsense presentation.

I'm curious to know where he takes the gameplay. He mentions it being digging-focused, and also mentions the digging/terrain deformation aspects in other games like No Man's Sky are relatively low-fidelity. I wonder what a "high-fidelity digging game" looks like (:

Aside, if I may self-plug: I wrote a small series on SDFs, for those who might be interested[1]. I'm also using them in my game engine (though it's 2D, for me).

[1]

* https://festina-lente-productions.com/articles/sdfs-1/

* https://festina-lente-productions.com/articles/sdfs-2/

* https://festina-lente-productions.com/articles/sdfs-3/

nnevatie 1/12/2026||
Seems you're not familiar with how game projects with a custom engine typically go. Let me elaborate on this - the steps involved are:

1. Create a custom game engine.

turtledragonfly 1/12/2026|||
Why must you attack me personally like this?! ⠀(:
nnevatie 1/12/2026||
Heh, I'm as guilty of this myself. Here's one example of mine: https://github.com/nnevatie/paybacktime
AlienRobot 1/12/2026||||
"Is rust good for game development? Rust is good for everything. There are currently... 5 games written in rust. And 50 game engines."[0]

[0] https://www.youtube.com/watch?v=TGfQu0bQTKc

account42 1/12/2026||||
So similar to the average game project with an off the shelf engine, just with an additional fun step.
ux266478 1/12/2026|||
That's how the overwhelming majority of all game projects go, custom engine or not.
plagiarist 1/12/2026||
I am interested in the small series and also the game engine (if not covered in the series). I will read these, thank you for sharing.
mbullington 1/11/2026||
Go Mike! Been seeing his progress for a while on Bluesky, I knew exactly (and who) what this was when I saw it on HN.

I was rendering-curious when we overlapped together at Figma. Mike was super patient and giving with his time, answering all my dumb questions and aiding with my Maker Week projects. Excited to see him take on something so ambitious next.

rjh29 1/8/2026||
Really impressive work. He covers it at the end, but being able to create tunnels into terrain, walk through them and then make the terrain disappear. Or make holes in the ground and move them around to suck items in. Or dynamically erase or add to any terrain in real time. A lot of interesting gameplay opportunities here and surprisingly performant!
program_whiz 1/12/2026||
I really respect his work on the engine, the math, and the engineering is excellent, but I'm not sure it makes for an interesting game above and beyond what we already have.

Adding additional smoothness to existing voxel engines I'm not sure would have much effect, unless you have something specific like moving a ball on a smooth surface (but the SDF I'm seeing here wouldn't support that either).

As for "create a hole, then close it behind you", this is about as game-changing as open/closing doors (or tunnels with doors). I'm open to suggestion, but honestly this is amazing tech, I just don't think it will create very fun games.

Kind of feel the same about the demos I see of spherical or non-euclidean geometry games. Its very interesting, and impressive, but seems like it is an engine in search of a game.

hahn-kev 1/12/2026|||
Yeah that's what I felt watch that video.
mikkupikku 1/12/2026|||
HyperRogue pulled it off.
program_whiz 1/12/2026||
Maybe one other thing to consider -- I think its usually best to have a killer game idea that seems fun, then design around it (and select the proper engine), rather than simply "I want to build an engine with some capabilities, then I'll figure out what games to make later."

Have seen this with a lot of software "frameworks" (web, game, graphics, etc.). Nothing wrong with writing an amazing tech demo just for the hell of it, but then when it comes time to do "real world" tasks, the frameworks are often in search of a fitting problem.

msephton 1/9/2026||
Great video. A new game engine powered by SDFs is the sort of thing I want to find out about. Not the next game in a long running franchise that looks the same as all the others that preceded it. One for the from-scratch game dev nerds like myself!
rendaw 1/12/2026|
Tangentially related, but here's another game based on SDFs and geometry manipulation, for 4D movement: https://www.youtube.com/watch?v=yeCqfqE4ylk

Stylistically there are similarities...

yunruse 1/8/2026||
The physics engine mentioned towards the end, Jolt Physics [0] is used in the frankly blockbuster games Horizon: Forbidden West and Death Stranding 2 and yet opens its description with

> Why create yet another physics engine? Firstly, it has been a personal learning project.

which is really rather wonderful and inspiring to see.

[0] https://github.com/jrouwe/JoltPhysics

armada651 1/11/2026||
Its use in those games is no mere coincidence though, the creator of that physics engine, Jorrit Rouwé, has worked at Guerilla Games since the Killzone days.

https://jrouwe.nl/games.php

V__ 1/11/2026|||
It has also become the default physics engine in Godot.
thom 1/11/2026||
Also increasingly well integrated into Godot.
num3ric 1/11/2026||
I wonder if ReLU fields could help reduce cache grid resolution while improving reconstruction precision? See https://arxiv.org/abs/2205.10824
tamat 1/12/2026||
the problem with SDF engines is that you have to reinvent everything, as current pipelines rely on triangles.

That means:

- Software to model using SDF (like Womp)

- Technique to animate skeletons using SDFs

- Tool to procedural texture surfaces using SDFs

At least he solved the physics part, which is also complex.

And also, his way of carving is by instantiating new elements, which works for small carves, but if you plan to have lots of tunels, then the number of instances is going to skyrocket.

andybak 1/12/2026|
Although a decent chunk of modern tooling is there to handle the limitations of triangles. And modelling is often using higher-level abstractions that are only turned into triangles at the end of the process.
cyber_kinetist 1/12/2026||
That's true if you're using a CAD-like tool, but that's typically not used for art (more for engineering / mechanical design)

Game / VFX artists heavily use mesh-based tools such as Maya or Blender.

andybak 1/16/2026||
Both have many tools that aren't raw triangle editing
cubefox 1/11/2026||
Almost every 3D game uses textured polygons almost everywhere (except sometimes for fog or clouds), so this SDF engine is nice to see.

However, he doesn't mention animations, especially skeletal animations. Those tend to work poorly or not at all without polygons. PS4 Dreams, another SDF engine, also had strong limitations with regards to animation. I hope he can figure something out, though perhaps his game project doesn't need animation anyway.

01HNNWZ0MV43FF 1/11/2026||
His SDF probably puts out a depth buffer, so with some effort (shadows might be hard?) you can just mix it with traditional polygons. The same way raytracing and polygons mix in AAA games.

He's using the SDFs to fill a space sort of like Unreal's Nanite virtual geometry. Nanite also doesn't support general animation. They only recently added support for foliage. So you'd use SDF / Nanite for your "infinite detail" / kit-bashing individual pebbles all the way to the horizon, and then draw polygon characters and props on top of that.

In fact I was surprised to see that Nanite flipped from triangle supremacy to using voxels in their new foliage tech. So maybe the two technologies will converge. The guy who did the initial research for Nanite (his talk also cites Dreams ofc) said that voxels weren't practical. But I guess they hit the limits of what they can do with pixel-sized triangles.

cubefox 1/12/2026||
I think they do now support skeletal meshes with virtual geometry: https://dev.epicgames.com/documentation/en-us/unreal-engine/...

Though it says "experimental". Unclear what that means in practice.

This also mentions "skinning": https://dev.epicgames.com/documentation/en-us/unreal-engine/... I believe thats just another term for skeletal meshes / "bones".

Boxxed 1/11/2026||
I'm not super familiar with this area so I don't follow... Why is animation any more difficult? I would think you could attach the basic 3D shapes to a skeleton the same way you would with polygons.
dahart 1/11/2026||
There are lots of reasons you don’t see a lot of SDF skeletal rigging & animation in games. It’s harder because the distance evaluations get much more expensive when you attach a hierarchy of warps and transforms, and there are typically a lot of distance evaluations when doing ray-marching. This project reduces the cost by using a voxel cache, but animated stuff thwarts the caching, so you have to limit the amount of animation. Another reason it’s more difficult to rig & animate SDFs is because you only get a limited set of shapes that have analytic distance functions, or you have primitives and blending and warping that break Lipschitz conditions in your distance field, which is a fancy way of saying it’s easy to break the SDF and there are only limited and expensive ways to fix it. SDFs are much better at representing procedural content than the kind of mesh modeling involved in character animation and rendering.
MITSardine 1/12/2026||
One possibility, a little backwards maybe, is to produce a discrete SDF from e.g. a mesh, by inserting it in an octree. The caching becomes the SDF itself, basically. This would let rendering be done via the SDF, but other logic could use the mesh (or other spatial data structure).

Or could the engine treat animated objects as traditional meshed objects (both rendering and interactions)? The author says all physics is done with meshes, so such objects could still interact with the game world seemingly easily. I imagine this would be limited to characters and such. I think they would look terrible using interpolation on a fixed grid anyways as a rotation would move the geometry around slightly, making these objects appear "blurry" in motion.

Jarmsy 1/12/2026||
Sampling an implicit function on a grid shifts you to the world of voxel processing, which has its own strengths and weaknesses. Further processing is lossy (like with raster image processing), storage requirements go up, recovering sharp edges is harder...
MITSardine 1/12/2026||
But isn't this what the author is doing already? That's what I got from the video. SDF is sampled on a sparse grid (only cells that cross the level set 0) and then values are sampled by interpolating on the grid rather than full reevaluation.
deckar01 1/11/2026||
Dreams on PS4 had an SDF modeler, but I’m not sure if the runtime was SDF. Now that I think about it, the rendering engine had a Gaussian splat look to it years before that paper.
turtledragonfly 1/11/2026||
The Dreams team made a nice talk at SIGGRAPH 2015, if you want to check it out:

* Slides (good notes): https://advances.realtimerendering.com/s2015/AlexEvans_SIGGR...

* video: https://www.youtube.com/watch?v=u9KNtnCZDMI

koolala 1/11/2026||
They discuss Dreams in the video and even explain Brick rendering.
jacobgorm 1/11/2026|
GameGlobe from Haptico and Square Enix, the engine of which also powered Project Spark from Microsoft, also used an SDF engine. Former colleagues of mine built the tech in Copenhagen and I remember getting a super impressive demo back then. This was the first time I heard of SDFs.
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