mirror of
https://github.com/CNCKitchen/stlTexturizer.git
synced 2026-04-07 22:11:32 +00:00
Avatarsia
3c9bcfd75c
Write binary STL directly from BufferGeometry typed arrays using Uint8Array.set() bulk copies. Eliminates the Three.js STLExporter overhead: no Mesh/Material creation, no identity matrix multiplication, no redundant normal recomputation, no per-float DataView calls.
72 lines
2.6 KiB
JavaScript
72 lines
2.6 KiB
JavaScript
/**
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* Fast binary STL exporter — writes directly from BufferGeometry arrays.
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*
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* Eliminates Three.js STLExporter overhead:
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* - No Mesh/Material creation
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* - No identity matrix multiplication per vertex
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* - No redundant normal recomputation
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* - Bulk Uint8Array.set() instead of per-float DataView calls
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*
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* @param {THREE.BufferGeometry} geometry – non-indexed with position + normal
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* @param {string} [filename]
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*/
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export function exportSTL(geometry, filename = 'textured.stl') {
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const posArr = geometry.attributes.position.array;
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const norArr = geometry.attributes.normal
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? geometry.attributes.normal.array
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: null;
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const triCount = (posArr.length / 9) | 0;
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// Binary STL: 80-byte header + 4-byte tri count + 50 bytes per triangle
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const bufLen = 84 + 50 * triCount;
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const buffer = new ArrayBuffer(bufLen);
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const bytes = new Uint8Array(buffer);
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const view = new DataView(buffer);
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// Header: 80 bytes (already zero-filled)
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view.setUint32(80, triCount, true);
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// Reinterpret source arrays as raw bytes for bulk copy
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const posSrc = new Uint8Array(posArr.buffer, posArr.byteOffset, posArr.byteLength);
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const norSrc = norArr
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? new Uint8Array(norArr.buffer, norArr.byteOffset, norArr.byteLength)
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: null;
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for (let i = 0; i < triCount; i++) {
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const dst = 84 + i * 50;
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const srcOff = i * 36; // 9 floats * 4 bytes
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if (norSrc) {
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// Normal: copy first vertex normal (12 bytes) — flat shading, all 3 identical
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bytes.set(norSrc.subarray(srcOff, srcOff + 12), dst);
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} else {
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// Compute face normal from cross product
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const b = i * 9;
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const ux = posArr[b+3]-posArr[b], uy = posArr[b+4]-posArr[b+1], uz = posArr[b+5]-posArr[b+2];
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const vx = posArr[b+6]-posArr[b], vy = posArr[b+7]-posArr[b+1], vz = posArr[b+8]-posArr[b+2];
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const nx = uy*vz-uz*vy, ny = uz*vx-ux*vz, nz = ux*vy-uy*vx;
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const len = Math.sqrt(nx*nx + ny*ny + nz*nz) || 1;
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view.setFloat32(dst, nx/len, true);
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view.setFloat32(dst + 4, ny/len, true);
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view.setFloat32(dst + 8, nz/len, true);
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}
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// Vertices: 36 bytes (3 vertices * 3 floats * 4 bytes)
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bytes.set(posSrc.subarray(srcOff, srcOff + 36), dst + 12);
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// Attribute byte count: 0 (already zero-filled)
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}
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// Download
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const blob = new Blob([buffer], { type: 'application/octet-stream' });
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const url = URL.createObjectURL(blob);
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const a = document.createElement('a');
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a.href = url;
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a.download = filename;
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a.style.display = 'none';
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document.body.appendChild(a);
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a.click();
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document.body.removeChild(a);
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setTimeout(() => URL.revokeObjectURL(url), 10000);
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}
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