diff --git a/apps/jscad-web/main.js b/apps/jscad-web/main.js
index 6a8d602..2ae9bea 100644
--- a/apps/jscad-web/main.js
+++ b/apps/jscad-web/main.js
@@ -13,6 +13,7 @@ import * as remote from './src/remote.js'
 import { formatStacktrace } from './src/stacktrace.js'
 import { ViewState } from './src/viewState.js'
 import * as welcome from './src/welcome.js'
+import { runMain } from '../../packages/worker/worker.js'
 
 export const byId = id => document.getElementById(id)
 const appBase = document.baseURI
@@ -20,6 +21,7 @@ let currentBase = appBase
 const toUrl = path => new URL(path, appBase).toString()
 
 const viewState = new ViewState()
+viewState.onRequireReRender = ()=>paramChangeCallback(lastParams)
 
 const gizmo = (window.gizmo = new Gizmo())
 byId('overlay').parentNode.appendChild(gizmo)
@@ -173,7 +175,7 @@ sendCmdAndSpin('init', {
   },
 }).then(() => {
   if (loadDefault) {
-    runScript({ script: defaultCode })
+    runScript({ script: defaultCode, smooth: viewState.smoothRender })
   }
 })
 
@@ -189,18 +191,18 @@ const paramChangeCallback = async params => {
   working = true
   let result
   try{
-    result = await sendCmdAndSpin('runMain', { params })
+    result = await sendCmdAndSpin('runMain', { params, smooth: viewState.smoothRender })
   } finally{
     working = false
   }
-  handlers.entities(result)
+  handlers.entities(result, {smooth: viewState.smoothRender})
   if(lastParams && lastParams != params) paramChangeCallback(lastParams)
 }
 
 const runScript = async ({ script, url = './index.js', base = currentBase, root }) => {
   currentBase = base
   loadDefault = false // don't load default model if something else was loaded
-  const result = await sendCmdAndSpin('runScript', { script, url, base, root })
+  const result = await sendCmdAndSpin('runScript', { script, url, base, root, smooth: viewState.smoothRender })
   genParams({ target: byId('paramsDiv'), params: result.def || {}, callback: paramChangeCallback })
   handlers.entities(result)
 }
diff --git a/apps/jscad-web/src/viewState.js b/apps/jscad-web/src/viewState.js
index ba54dbe..49b7108 100644
--- a/apps/jscad-web/src/viewState.js
+++ b/apps/jscad-web/src/viewState.js
@@ -16,6 +16,7 @@ export class ViewState {
     const darkMode = byId('dark-mode')
     const showAxis = byId('show-axis')
     const showGrid = byId('show-grid')
+    const smoothRender = byId('smooth-render')
     darkMode.addEventListener('change', () => {
       this.themeName = darkMode.checked ? 'dark' : 'light'
       if (darkMode.checked) {
@@ -25,6 +26,9 @@ export class ViewState {
       }
       this.setTheme(this.themeName)
     })
+    smoothRender.addEventListener('change', () => {
+      this.setSmoothRender(smoothRender.checked)
+    })
     showAxis.addEventListener('change', () => this.setAxes(showAxis.checked))
     showGrid.addEventListener('change', () => this.setGrid(showGrid.checked))
   }
@@ -41,6 +45,12 @@ export class ViewState {
     this.saveState()
   }
 
+  setSmoothRender(smoothRender, fireEvent = true) {
+    this.smoothRender = smoothRender
+    this.saveState()
+    if(fireEvent) this.onRequireReRender()
+  }
+
   setTheme(themeName) {
     if (!themes[themeName]) throw new Error(`unknown theme ${themeName}`)
     this.themeName = themeName
@@ -86,7 +96,7 @@ export class ViewState {
     if (grid) items.push({ id: 'grid', items: grid })
     if (model) items.push({ id: 'model', items: model })
 
-    this.viewer?.setScene({ items })
+    this.viewer?.setScene({ items }, {smooth:this.smoothRender})
   }
 
   setEngine(viewer) {
@@ -108,6 +118,8 @@ export class ViewState {
     byId('show-axis').checked = this.showAxis
     this.showGrid = localStorage.getItem('engine.showGrid') !== 'false'
     byId('show-grid').checked = this.showGrid
+    this.smoothRender = !!localStorage.getItem('engine.smoothRender')
+    byId('smooth-render').checked = this.smoothRender
     const cameraLocation = localStorage.getItem('camera.location')
     this.camera = cameraLocation ? JSON.parse(cameraLocation) : { position: [180, -180, 220] }
   }
@@ -116,5 +128,8 @@ export class ViewState {
     localStorage.setItem('engine.theme', this.themeName)
     localStorage.setItem('engine.showAxis', this.showAxis)
     localStorage.setItem('engine.showGrid', this.showGrid)
+    localStorage.setItem('engine.smoothRender', this.smoothRender)
   }
+
+  onRequireReRender(){}
 }
diff --git a/apps/jscad-web/static/index.html b/apps/jscad-web/static/index.html
index 8644dc0..17e8f24 100644
--- a/apps/jscad-web/static/index.html
+++ b/apps/jscad-web/static/index.html
@@ -82,6 +82,7 @@ <h2>Options</h2>
             <li><label for="dark-mode">Dark Mode</label><input type="checkbox" id="dark-mode"></li>
             <li><label for="show-axis">Show Axis</label><input type="checkbox" id="show-axis" checked></li>
             <li><label for="show-grid">Show Grid</label><input type="checkbox" id="show-grid" checked></li>
+            <li><label for="show-grid">Smooth render</label><input type="checkbox" id="smooth-render" checked></li>
           </ul>
 
           <h2>Documentation</h2>
diff --git a/packages/format-threejs/index.js b/packages/format-threejs/index.js
index 9f1a1cf..8418cf9 100644
--- a/packages/format-threejs/index.js
+++ b/packages/format-threejs/index.js
@@ -25,7 +25,7 @@ export function CommonToThree({
   materials.lines = materials.line
   materials.instance = materials.mesh // todo support instances for lines
 
-  function _CSG2Three(obj, { smooth = true }) {
+  function _CSG2Three(obj, { smooth = false }) {
     const { vertices, indices, normals, color, colors, isTransparent = false, opacity } = obj
     let { transforms } = obj
     const objType = obj.type || 'mesh'
diff --git a/packages/render-threejs/index.js b/packages/render-threejs/index.js
index c0466b3..d66513e 100644
--- a/packages/render-threejs/index.js
+++ b/packages/render-threejs/index.js
@@ -24,6 +24,7 @@ export function RenderThreejs({
   let _camera
   let controls
   let renderer
+  let smooth
   const SHADOW = false
   const shouldRender = Date.now()
   const lastRender = true
@@ -100,6 +101,10 @@ export function RenderThreejs({
     updateView()
   }
 
+  function setSmooth(v){
+    smooth = v
+  }
+
   function setMeshColor(bg = [1, 1, 1]) {
     meshColor = new Color(...bg)
     csgConvert.setDefColor(bg)
@@ -193,7 +198,8 @@ export function RenderThreejs({
     }
   }
 
-  function setScene(scene) {
+  function setScene(scene,{smooth}={}) {
+    console.warn('options', {smooth})
     groups.forEach(group => {
       _scene.remove(group)
     })
@@ -205,7 +211,7 @@ export function RenderThreejs({
       const group = new Group()
       groups.push(group)
       item.items.forEach(obj => {
-        const obj3d = csgConvert(obj, scene, meshColor)
+        const obj3d = csgConvert(obj, { smooth, scene, meshColor})
         if (obj3d) {
           entities.push(obj3d)
           group.add(obj3d)