feat: add STL and OBJ export formats (#175)

Extend the export manager to support STL and OBJ formats in addition to
the existing GLB export. Uses Three.js built-in STLExporter and
OBJExporter - no new dependencies.

STL is the standard format for 3D printing. OBJ is widely used in
rendering pipelines and supports basic materials. Both are requested
in the community discussion on #145.

Changes:
- export-manager.tsx: add STLExporter and OBJExporter, accept format param
- settings-panel: three format-specific export buttons (GLB, STL, OBJ)
- use-viewer store: update exportScene type to accept optional format

The format parameter defaults to 'glb', so existing callers (command
palette) continue to work without changes.

Relates to #145

Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/editor/src/components/editor/export-manager.tsx

@@ -4,13 +4,15 @@ import { useViewer } from '@pascal-app/viewer'
 import { useThree } from '@react-three/fiber'
 import { useEffect } from 'react'
 import { GLTFExporter } from 'three/examples/jsm/exporters/GLTFExporter.js'
+import { STLExporter } from 'three/examples/jsm/exporters/STLExporter.js'
+import { OBJExporter } from 'three/examples/jsm/exporters/OBJExporter.js'
 
 export function ExportManager() {
   const scene = useThree((state) => state.scene)
   const setExportScene = useViewer((state) => state.setExportScene)
 
   useEffect(() => {
-    const exportFn = async () => {
+    const exportFn = async (format: 'glb' | 'stl' | 'obj' = 'glb') => {
       // Find the scene renderer group by name
       const sceneGroup = scene.getObjectByName('scene-renderer')
       if (!sceneGroup) {
@@ -18,20 +20,33 @@ export function ExportManager() {
         return
       }
 
-      const exporter = new GLTFExporter()
       const date = new Date().toISOString().split('T')[0]
 
+      if (format === 'stl') {
+        const exporter = new STLExporter()
+        const result = exporter.parse(sceneGroup, { binary: true })
+        const blob = new Blob([result], { type: 'model/stl' })
+        downloadBlob(blob, `model_${date}.stl`)
+        return
+      }
+
+      if (format === 'obj') {
+        const exporter = new OBJExporter()
+        const result = exporter.parse(sceneGroup)
+        const blob = new Blob([result], { type: 'model/obj' })
+        downloadBlob(blob, `model_${date}.obj`)
+        return
+      }
+
+      // Default: GLB export (existing behavior)
+      const exporter = new GLTFExporter()
+
       return new Promise<void>((resolve, reject) => {
         exporter.parse(
           sceneGroup,
           (gltf) => {
             const blob = new Blob([gltf as ArrayBuffer], { type: 'model/gltf-binary' })
-            const url = URL.createObjectURL(blob)
-            const link = document.createElement('a')
-            link.href = url
-            link.download = `model_${date}.glb`
-            link.click()
-            URL.revokeObjectURL(url)
+            downloadBlob(blob, `model_${date}.glb`)
             resolve()
           },
           (error) => {
@@ -52,3 +67,12 @@ export function ExportManager() {
 
   return null
 }
+
+function downloadBlob(blob: Blob, filename: string) {
+  const url = URL.createObjectURL(blob)
+  const link = document.createElement('a')
+  link.href = url
+  link.download = filename
+  link.click()
+  URL.revokeObjectURL(url)
+}

packages/editor/src/components/ui/sidebar/panels/settings-panel/index.tsx

@@ -202,9 +202,9 @@ export function SettingsPanel({
 
   const isLocalProject = false // Props-based; only show cloud sections when projectId provided
 
-  const handleExport = async () => {
+  const handleExport = async (format: 'glb' | 'stl' | 'obj' = 'glb') => {
     if (exportScene) {
-      await exportScene()
+      await exportScene(format)
     }
   }
 
@@ -318,9 +318,17 @@ export function SettingsPanel({
       {/* Export Section */}
       <div className="space-y-2">
         <label className="font-medium text-muted-foreground text-xs uppercase">Export</label>
-        <Button className="w-full justify-start gap-2" onClick={handleExport} variant="outline">
+        <Button className="w-full justify-start gap-2" onClick={() => handleExport('glb')} variant="outline">
           <Download className="size-4" />
-          Export 3D Model
+          Export as GLB
+        </Button>
+        <Button className="w-full justify-start gap-2" onClick={() => handleExport('stl')} variant="outline">
+          <Download className="size-4" />
+          Export as STL
+        </Button>
+        <Button className="w-full justify-start gap-2" onClick={() => handleExport('obj')} variant="outline">
+          <Download className="size-4" />
+          Export as OBJ
         </Button>
       </div>