stub in menu for normals inversion

src/mesh/api.js

@@ -313,6 +313,12 @@ let tool = {
         }
     },
 
+    invert() {
+        for (let m of selection.models(true)) {
+            m.invert(api.mode.get());
+        }
+    },
+
     analyze(models) {
         models = fallback(models);
         api.log.emit('analyzing mesh(es)...').pin();

src/mesh/build.js

@@ -242,6 +242,7 @@ function ui_build() {
             h.div({ class: "vsep" }),
             h.button({ _: 'duplicate', onclick: tool.duplicate }),
             h.button({ _: 'merge', onclick: tool.merge }),
+            h.button({ _: 'invert', onclick: tool.invert }),
             h.div({ class: "vsep" }),
             h.button({ _: 'analyze', onclick: tool.analyze }),
             h.button({ _: 'repair', onclick: tool.repair }),

src/mesh/model.js

@@ -303,6 +303,18 @@ mesh.model = class MeshModel extends mesh.object {
         }
     }
 
+    // invert normals for entire mesh or selected faces depending on mod
+    invert(mode) {
+        let { modes } = mesh.api;
+        switch (mode) {
+            case modes.object:
+                break;
+            case modes.face:
+                break;
+        }
+    }
+
+    // remove model from group and space
     remove() {
         if (arguments.length === 0) {
             // direct call requires pass through group