add grid lines toggling

src/mesh/api.js

@@ -267,6 +267,14 @@ let api = mesh.api = {
         ));
     },
 
+    grid(state = {toggle:true}) {
+        if (state.toggle) {
+            space.platform.showGrid(!space.platform.isGridVisible());
+        } else {
+            space.platform.showGrid(state);
+        }
+    },
+
     wireframe(state = {toggle:true}, opt = {opacity:0.15}) {
         for (let m of api.model.list()) {
             m.wireframe(state, opt);

src/mesh/build.js

@@ -179,6 +179,7 @@ function ui_build() {
             h.button({ _: 'analyze', disabled: true }),
             h.button({ _: 'repair', onclick: api.tool.repair }),
             h.div({ class: "vsep" }),
+            h.button({ _: 'gridlines', onclick() { api.grid() } }),
             h.button({ _: 'wireframe', onclick() { api.wireframe() } }),
         ]),
     ]);