new model viewer

src/client/viewer/main.ts

@@ -179,6 +179,24 @@ function makeMaterial(color: [number, number, number] | null): THREE.MeshStandar
   })
 }
 
+// ---- Binary decode helpers (geometry v2) ---------------------------------
+
+function b64ToFloat32(b64: string): Float32Array {
+  const bin = atob(b64)
+  const buf = new ArrayBuffer(bin.length)
+  const u8  = new Uint8Array(buf)
+  for (let i = 0; i < bin.length; i++) u8[i] = bin.charCodeAt(i)
+  return new Float32Array(buf)
+}
+
+function b64ToUint32(b64: string): Uint32Array {
+  const bin = atob(b64)
+  const buf = new ArrayBuffer(bin.length)
+  const u8  = new Uint8Array(buf)
+  for (let i = 0; i < bin.length; i++) u8[i] = bin.charCodeAt(i)
+  return new Uint32Array(buf)
+}
+
 // ---- STEP/STP loader (geometry JSON, pre-processed server-side) ----------
 
 async function loadStepGeometry(): Promise<void> {
@@ -193,28 +211,64 @@ async function loadStepGeometry(): Promise<void> {
     throw new Error(`Could not load geometry (HTTP ${res.status})`)
   }
 
-  setLoading('Building 3D scene…')
-  const data = await res.json() as GeometryFile
+  // Stream the response body so there is visible activity during large downloads
+  let text: string
+  if (res.body) {
+    const reader = res.body.getReader()
+    const chunks: Uint8Array[] = []
+    let loaded = 0
+    while (true) {
+      const { done, value } = await reader.read()
+      if (done) break
+      chunks.push(value)
+      loaded += value.byteLength
+      setLoading(`Downloading geometry… ${Math.round(loaded / 1024)} KB`)
+    }
+    setLoading('Parsing geometry…')
+    text = new TextDecoder().decode(
+      chunks.reduce((acc, c) => { const m = new Uint8Array(acc.length + c.length); m.set(acc); m.set(c, acc.length); return m }, new Uint8Array(0))
+    )
+  } else {
+    text = await res.text()
+  }
+
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const data = JSON.parse(text) as GeometryFile & { version: number; meshes: any[] }
 
   if (!data.meshes || data.meshes.length === 0) {
     throw new Error('Geometry file contains no meshes.')
   }
 
+  setLoading('Building 3D scene…')
   const group = new THREE.Group()
+  const isV2  = data.version >= 2
 
   for (const mesh of data.meshes) {
     const geo = new THREE.BufferGeometry()
-    geo.setAttribute('position', new THREE.Float32BufferAttribute(mesh.positions, 3))
 
-    if (mesh.normals && mesh.normals.length > 0) {
-      geo.setAttribute('normal', new THREE.Float32BufferAttribute(mesh.normals, 3))
+    let positions: Float32Array
+    let normals:   Float32Array | null
+    let indices:   Uint32Array  | null
+
+    if (isV2) {
+      positions = b64ToFloat32(mesh.positions)
+      normals   = mesh.normals ? b64ToFloat32(mesh.normals) : null
+      indices   = mesh.indices ? b64ToUint32(mesh.indices)  : null
+    } else {
+      // Legacy v1: plain number arrays
+      positions = new Float32Array(mesh.positions as number[])
+      normals   = mesh.normals ? new Float32Array(mesh.normals as number[]) : null
+      indices   = mesh.indices ? new Uint32Array(mesh.indices as number[])  : null
     }
 
-    if (mesh.indices && mesh.indices.length > 0) {
-      geo.setIndex(new THREE.Uint32BufferAttribute(mesh.indices, 1))
+    geo.setAttribute('position', new THREE.Float32BufferAttribute(positions, 3))
+    if (normals && normals.length > 0) {
+      geo.setAttribute('normal', new THREE.Float32BufferAttribute(normals, 3))
     }
-
-    if (!mesh.normals || mesh.normals.length === 0) {
+    if (indices && indices.length > 0) {
+      geo.setIndex(new THREE.Uint32BufferAttribute(indices, 1))
+    }
+    if (!normals || normals.length === 0) {
       geo.computeVertexNormals()
     }
 

src/server/services/stepConverter.ts

@@ -3,14 +3,14 @@ import fs from 'fs'
 import path from 'path'
 
 export interface GeometryMesh {
-  positions: number[]
-  normals:   number[] | null
-  indices:   number[]
+  positions: string              // base64-encoded Float32Array
+  normals:   string | null       // base64-encoded Float32Array
+  indices:   string              // base64-encoded Uint32Array
   color:     [number, number, number] | null
 }
 
 export interface GeometryFile {
-  version:    1
+  version:    2
   sourceFile: string
   meshCount:  number
   meshes:     GeometryMesh[]
@@ -45,15 +45,20 @@ export async function convertStepFile(
   }
 
   const geo: GeometryFile = {
-    version:    1,
+    version:    2,
     sourceFile: path.basename(inputPath),
     meshCount:  result.meshes.length,
-    meshes: result.meshes.map(mesh => ({
-      positions: Array.from(mesh.attributes.position.array),
-      normals:   mesh.attributes.normal ? Array.from(mesh.attributes.normal.array) : null,
-      indices:   Array.from(mesh.index.array),
+    meshes: result.meshes.map(mesh => {
+      const pos = mesh.attributes.position.array
+      const nor = mesh.attributes.normal?.array
+      const idx = mesh.index.array
+      return {
+        positions: Buffer.from(pos.buffer, pos.byteOffset, pos.byteLength).toString('base64'),
+        normals:   nor ? Buffer.from(nor.buffer, nor.byteOffset, nor.byteLength).toString('base64') : null,
+        indices:   Buffer.from(idx.buffer, idx.byteOffset, idx.byteLength).toString('base64'),
         color:     mesh.color ? [mesh.color[0], mesh.color[1], mesh.color[2]] : null,
-    })),
+      }
+    }),
   }
 
   fs.writeFileSync(outputPath, JSON.stringify(geo))

src/server/services/thumbnailGenerator.ts

@@ -60,8 +60,10 @@ export function thumbnailOutputPath(uploadsDir: string, modelId: number | bigint
 export function geometryToTriangles(geo: GeometryFile): ThumbTri[] {
   const tris: ThumbTri[] = []
   for (const mesh of geo.meshes) {
-    const pos  = mesh.positions
-    const idx  = mesh.indices
+    const posBuf = Buffer.from(mesh.positions, 'base64')
+    const idxBuf = Buffer.from(mesh.indices,   'base64')
+    const pos = new Float32Array(posBuf.buffer, posBuf.byteOffset, posBuf.byteLength / 4)
+    const idx = new Uint32Array(idxBuf.buffer,  idxBuf.byteOffset,  idxBuf.byteLength / 4)
     const r   = mesh.color ? Math.round(mesh.color[0] * 255) : 136
     const g   = mesh.color ? Math.round(mesh.color[1] * 255) : 153
     const b   = mesh.color ? Math.round(mesh.color[2] * 255) : 170