There are many ways to generalize the Hilbert curve to three dimensions. We chose the approach that came with code. stackoverflow 
const s = .2 // size of box const n = 2**2 // number of hilbert recursions let k = 45 // down counting limit to boxes
We had geometry, material and mesh to place boxes that came out of the hilbert function. Following that logic we drew a bar with all but the first box.
We sought help again positioning that bar in the right place and pointing it in the right direction. stackoverflow
let last = null const geo = new THREE.BoxGeometry(s,s,s) const bar = new THREE.BoxGeometry(s/2,s/2,1) bar.translate(0, 0, 1/2) const mat = new THREE.MeshNormalMaterial() const box = point => { if (k-- > 0) { let box = new THREE.Mesh(geo, mat) box.position.set(...point) scene.add(box) if(last) { box = new THREE.Mesh(bar, mat) box.position.set(...last) box.lookAt(...point) scene.add(box) } last = point } }
h3(n,0,0,0,1,0,0,0,1,0,0,0,1) function h3(s,x,y,z,dx,dy,dz,x2,y2,z2,x3,y3,z3){ if(s==1){ box([x,y,z]) } else { s/=2; if(dx<0) x-=s*dx; if(dy<0) y-=s*dy; if(dz<0) z-=s*dz; if(x2<0) x-=s*x2; if(y2<0) y-=s*y2; if(z2<0) z-=s*z2; if(x3<0) x-=s*x3; if(y3<0) y-=s*y3; if(z3<0) z-=s*z3; h3(s,x,y,z,x2,y2,z2,x3,y3,z3,dx,dy,dz); h3(s,x+s*dx,y+s*dy,z+s*dz,x3,y3,z3, dx,dy,dz,x2,y2,z2); h3(s,x+s*dx+s*x2,y+s*dy+s*y2,z+s*dz+s*z2, x3,y3,z3,dx,dy,dz,x2,y2,z2); h3(s,x+s*x2,y+s*y2,z+s*z2,-dx,-dy,-dz, -x2,-y2,-z2,x3,y3,z3); h3(s,x+s*x2+s*x3,y+s*y2+s*y3,z+s*z2+s*z3, -dx,-dy,-dz,-x2,-y2,-z2,x3,y3,z3); h3(s,x+s*dx+s*x2+s*x3,y+s*dy+s*y2+s*y3, z+s*dz+s*z2+s*z3, -x3,-y3,-z3,dx,dy,dz,-x2,-y2,-z2); h3(s,x+s*dx+s*x3,y+s*dy+s*y3,z+s*dz+s*z3, -x3,-y3,-z3,dx,dy,dz,-x2,-y2,-z2); h3(s,x+s*x3,y+s*y3,z+s*z3,x2,y2,z2, -x3,-y3,-z3,-dx,-dy,-dz); } }
controls.autoRotate = false
//wiki.ralfbarkow.ch/assets/pages/snippet-template/save.html HEIGHT 420
control-drag to center image.