Sculpting SDF shapes: blends, symmetry, and domain repetition

This module is where a raymarched scene stops looking like floating geometry-demo spheres and starts looking like something you would put on screen at a show. In a live-coding visual set — a fragment shader hot-reloading behind the audio rig — you rarely have time to model anything. Instead you sculpt: a couple of primitives, merged, mirrored, warped, and multiplied until one distance function reads as a creature, a colony, a landscape. Everything here is a transformation of either the distance value or the input coordinate, which is why it stays fast enough to run per-pixel at 60fps.

The arc starts supported. First exercise: take two spheres from your first-SDF-scene module and join them with the smooth minimum, sweeping the blend radius k live to feel how the crease rounds into an organic merge. Then swap a sphere for an ellipsoid via space scaling, and add a feature on one side only — an eye, a fin — and mirror it for free with the abs-symmetry trick, watching for the classic half-shape-on-the-axis pitfall. Next, bend the form itself by perturbing p before evaluation (the displacement atom is your JIT pointer here, including its warning about breaking the distance bound). Finally, wrap the whole sculpt in domain repetition and use the floor-derived cell ID to vary each copy, so the tiled field reads alive rather than synthetic.

The capstone is the same task unsupported: one organic form, blended, mirrored, displaced, tiled with per-cell variation. Each required atom gates one of those verbs — skip any and the capstone visibly fails. The supporting atoms enrich: triplet-based rotations give cheap exact tilts to break symmetry tastefully, and scale-to-zero discard is a neighbouring instancing idea from the mesh world that contextualises why repetition-by-coordinate-folding is such a win.

Runnable examples

Generated from the context/ instrument corpus by concept (redistributable idioms only). Do not edit — regenerate with gen-module-examples.mjs.

tiling-repeat

osc(10).repeat(3, 3).out()

_{hydra-0008 · CC0-1.0}

tile [4,4] (circle 0 0.3) >> add

_{punctual-0020 · CC0-1.0}

radial-symmetry

osc(10).kaleid(5).out()

_{hydra-0010 · CC0-1.0}

// sandbox
osc(10, 0.05, 1.3).kaleid(8).out()
// sandbox

_{p5live-0037 · CC0-1.0}

sdf-shape

circle [0,0] 0.4 >> add

_{punctual-0018 · CC0-1.0}

float d = length(uv) - r;

_{glsl-0003 · public-domain}

mirror

uv = abs(uv);

_{glsl-0010 · public-domain}

osc(10).kaleid(2).out()

_{hydra-0011 · CC0-1.0}

boolean-sdf

float u = min(a, b); float s = max(a, -b);

_{glsl-0006 · public-domain}