perf(obj-serializer): improved performance by using Map for unique vertices

Author: ZephyrRaine

packages/io/obj-serializer/index.js

@@ -69,8 +69,8 @@ const serialize = (options, ...objects) => {
   // construct the contents of the OBJ file
   let body = '# Wavefront OBJ file generated by JSCAD\n'
 
-  // find unique vertices
-  const vertices = []
+  // find unique vertices - use Map for O(1) lookup instead of O(n) indexOf
+  const vertexMap = new Map() // vertex string -> index (1-based)
 
   // convert objects
   // TODO: group objects together
@@ -86,9 +86,10 @@ const serialize = (options, ...objects) => {
     polygons.forEach((polygon) => {
       polygon.vertices.forEach((vertex) => {
         const vertexString = convertVertex(vertex)
-        if (vertices.indexOf(vertexString) < 0) {
+        if (!vertexMap.has(vertexString)) {
           // add unique vertices
-          vertices.push(vertexString)
+          const index = vertexMap.size + 1 // OBJ uses 1-based indexing
+          vertexMap.set(vertexString, index)
           body += `${vertexString}\n`
         }
       })
@@ -99,7 +100,7 @@ const serialize = (options, ...objects) => {
     polygons.forEach((polygon) => {
       // convert vertices to indices
       const indices = polygon.vertices
-        .map((v) => vertices.indexOf(convertVertex(v)) + 1)
+        .map((v) => vertexMap.get(convertVertex(v)))
       // set face color
       const color = getColorName(polygon) || objectColor || 'default'
       if (color !== previousColor) {