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Free SDF raymarcher for Godot 4 metaballs that blend colors, in one shader (CC0 + MIT) (programming.dev)
submitted 1 week ago* (last edited 1 week ago) by to c/godot@programming.dev
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Signed distance field raymarching in Godot 4, authored with nodes. Physics-driven metaballs melt into the SDF cubes in one fullscreen pass, and since every CSG op works on (color, distance) pairs, the colors blend along with the shapes.

Two free editions: Standalone shader (CC0): one .gdshader, no scripts paste onto a QuadMesh, edit map(). Godot Shaders https://godotshaders.com/shader/fullscreen-sdf-raymarching-with-smooth-csg-and-depth/

Node-based project (MIT): shapes as Node3D nodes, live editor preview, physics, up to 32 primitives and a write-up. VavLabs Mit
https://vav-labs.com/case-studies/sdf-raymarcher-godot/

Distance functions after Inigo Quilez.

youtube: https://youtu.be/Y1sd9Cx4NAs

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[–] 3 points 1 week ago (1 child)

To my knowledge, this is the first time anyone has done this in Godot, and that in itself is very impressive.

I was fucking around with my own attempt at giving Godot a kind of octree based ... spatial framework, if that makes any sense... I wonder what that and this could do together.

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  • [–] 2 points 1 week ago*

    To my knowledge, this is the first time anyone has done this in Godot

    There is Zylann's godot_sdf_blender. Not sure how it compares, though.

    octree based

    It would be cool to have Cube 2: Sauerbraten map support (I especially like things like arches and other mesh details). Though a lot of the look can be done with meshes+vertex colors (more materials for things like glow, metal) the missing piece for me is the map editing workflow* particularly something more intended for modularity (Godot's gridmap is clunky when it comes to multiple cell sizes).

    * I haven't been able to try the new vertex snapping, nor Trenchbroom/Cyclops

    I wonder what that and this could do together.

    Excavation game? Both in terms of globbing dirt to walls, and dynamically dividing walls down that convert to SDF objects when small enough for digged surface. Actually this seems to exist as well, JorisAR's GDVoxelTerrain:

    This project adds a smooth voxel terrain system to godot. More precisely, it uses an octree to store an SDF, which is then meshed using a custom version of surface nets. Level of detail systems are in place for large viewing distances.

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    • [–] 2 points 1 week ago (1 child)

    up to 32 primitives

    This seems very low unless it's nuanced or multiple tricks can be used. Joined operations/volumes/surfaces, scheduled calculations etc. So I'd like to see what can be implemented in more examples.

    The SIGGRAPH talk for PixelJunk Shooter 2 covers things like this albeit 2D, distance fields are used for the walls (2, static+dynamic, merged into 1), different shader techniques for liquids.

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  • [–] [S] 3 points 1 week ago

    32 is a deliberate ceiling for this edition, not a limit of the technique. The design goal was set no compute no buffers one file shapes travel as uniform arrays, and every primitive adds a distance eval to every march step on every pixel, so a fully analytic field doesn't want hundreds anyway. The scaling tricks are exactly the ones you list bake everything static into a precomputed SDF texture and sample it as a single primitive. That's the natural direction for the node based edition if it grows to v2

    Hadn't seen the liquids part of that SIGGRAPH talk thanks for the pointer, watching it.

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