AA battery pair

const MATERIAL={"schemaVersion": 3, "model": "pbrMetallicRoughness", "name": "Fictional battery cream and dark green labels", "roughness": 0.7, "metalness": 0.12, "emissiveIntensity": 1, "alphaMode": "opaque", "alphaCutoff": 0.5, "doubleSided": false, "textures": {"baseColor": {"kind": "resource", "resourceId": "kiln.library.40df14512765020548fa35dee36441e252843352d8cdcd7a8252a51ee049d07f.base-color", "sampler": {"minFilter": "nearest", "magFilter": "nearest", "wrapS": "clamp-to-edge", "wrapT": "clamp-to-edge"}}}};
const meta={name:'AA battery pair',role:'prop'};
// Real 50mm tall cells, 14mm nominal diameter. Presentation enlargement is consumer-only.
const PROFILE=[[0,.0066],[.0007,.007],[.047,.007],[.048,.0066]];
function buffer(){return {p:[],uv:[]};}
function tri(o,p,uv){for(let k=0;k<3;k++){o.p.push(...p[k]);o.uv.push(...uv[k]);}}
function quad(o,p,uv){tri(o,[p[0],p[1],p[2]],[uv[0],uv[1],uv[2]]);tri(o,[p[0],p[2],p[3]],[uv[0],uv[2],uv[3]]);}
function ring(x,z,y,r){return Array.from({length:8},(_,k)=>{const a=k*2*Math.PI/8-Math.PI/2;return[x+Math.cos(a)*r,y,z+Math.sin(a)*r];});}
function cap(o,x,z,y,r,up,region){const p=ring(x,z,y,r);for(let k=1;k<7;k++){const ids=up?[0,k+1,k]:[0,k,k+1];tri(o,ids.map(i=>p[i]),ids.map(i=>[.5+.4*Math.cos(i*2*Math.PI/8),region[0]+(region[1]-region[0])*(.5+.4*Math.sin(i*2*Math.PI/8))]));}}
function cell(o,x,z){const rings=PROFILE.map(([y,r])=>ring(x,z,y,r));for(let k=0;k<3;k++)for(let i=0;i<8;i++){const q=(i+1)%8,lo=k===1?.05:.635,hi=k===1?.455:.735;quad(o,[rings[k][i],rings[k+1][i],rings[k+1][q],rings[k][q]],[[i/8,lo],[i/8,hi],[(i+1)/8,hi],[(i+1)/8,lo]]);}cap(o,x,z,0,.0066,false,[.51,.615]);cap(o,x,z,.048,.0066,true,[.51,.615]);const a=ring(x,z,.048,.0028),b=ring(x,z,.050,.0028);for(let i=0;i<8;i++){const q=(i+1)%8;quad(o,[a[i],b[i],b[q],a[q]],[[.2,.51],[.2,.615],[.8,.615],[.8,.51]]);}cap(o,x,z,.050,.0028,true,[.51,.615]);}
function band(o){const d=.007*Math.SQRT1_2,outline=[[-.007,-.0076],[-d,-.0076-d],[0,-.0146],[d,-.0076-d],[.007,-.0076],[.007,.0076],[d,.0076+d],[0,.0146],[-d,.0076+d],[-.007,.0076]],bottom=.019,top=.029;for(let i=0;i<outline.length;i++){const a=outline[i],b=outline[(i+1)%outline.length];quad(o,[[a[0],bottom,a[1]],[a[0],top,a[1]],[b[0],top,b[1]],[b[0],bottom,b[1]]],[[i/outline.length,.758],[i/outline.length,.995],[(i+1)/outline.length,.995],[(i+1)/outline.length,.758]]);}}
async function build(){const root=createRoot('BatteryPair'),mat=await compilePortableMaterialSpecV3(MATERIAL),o=buffer();cell(o,0,-.0076);cell(o,0,.0076);band(o);const g=new THREE.BufferGeometry();g.setAttribute('position',new THREE.Float32BufferAttribute(o.p,3));g.setAttribute('uv',new THREE.Float32BufferAttribute(o.uv.map((v,i)=>i%2?1-v:v),2));g.computeVertexNormals();const mesh=new THREE.Mesh(g,mat);mesh.name='BatteryPair_CellsAndPaperBand';root.add(mesh);markOpenShell(mesh,'Intentional thin open paper strap around two closed cell bodies; overlaps attach the band, no manufacturing-solid claim.');for(const [name,pos]of [['pickup_root',[0,0,0]],['display_center',[0,.025,0]],['cell_left_positive',[0,.050,-.0076]],['cell_right_positive',[0,.050,.0076]]]){const a=new THREE.Object3D();a.name=name;a.position.set(...pos);root.add(a);}root.userData.batteryPickup={version:1,cellNominalDimensions:[.014,.050,.014],cellCount:2,canonicalScale:1,suggestedConsumerPresentationScale:2.5,axes:'+X forward,+Y cells up,+Z right',band:'thin fictional paper label strap',runtimeOnly:'Floating rotation/pickup collision/inventory are scene-owned; canonical AA dimensions are preserved.'};return root;}