add error message if webgl is not supported

src/core/Markdown.js

@@ -89,8 +89,8 @@ export default class MarkdownParser {
       // beginning of line
       const paraLineStart = iter;
       if (indent && this.getIndent(text, paraLineStart) <= indent) {
-        //smaller indent occured
-        
+        // smaller indent occured
+
       }
       iter = this.skipSpaces(text, iter);
       if (stoppingCondition(text, iter)) {

src/core/utils.js

@@ -316,3 +316,16 @@ export function createNameRegExp(name: string) {
   if (!name) return null;
   return new RegExp(`(^|\\s+)(@${escapeRegExp(name)})(\\s+|$)`, 'g');
 }
+
+/*
+ * check if webGL2 is available
+ * @return boolean true if available
+ */
+export function isWebGL2Available() {
+  try {
+    const canvas = document.createElement('canvas');
+    return !!(window.WebGL2RenderingContext && canvas.getContext('webgl2'));
+  } catch {
+    return false;
+  }
+}

src/ui/renderer.js

@@ -6,15 +6,22 @@
  * @flow
  */
 
-import Renderer2D from './Renderer2D';
+import { t } from 'ttag';
 
-let renderer = {
+import Renderer2D from './Renderer2D';
+import { sweetAlert } from '../actions';
+import { isWebGL2Available } from '../core/utils';
+
+const dummyRenderer = {
+  is3D: null, 
   render: () => null,
   destructor: () => null,
   renderPixel: () => null,
   updateCanvasData: () => null,
 };
 
+let renderer = dummyRenderer;
+
 function animationLoop() {
   renderer.render();
   window.requestAnimationFrame(animationLoop);
@@ -24,10 +31,20 @@ animationLoop();
 export async function initRenderer(store, is3D: boolean) {
   renderer.destructor();
   if (is3D) {
-    /* eslint-disable-next-line max-len */
-    const module = await import(/* webpackChunkName: "voxel" */ '../ui/Renderer3D');
-    const Renderer3D = module.default;
-    renderer = new Renderer3D(store);
+    if (!isWebGL2Available()) {
+      store.dispatch(sweetAlert(
+        t`Canvas Error`,
+        t`Can't render 3D canvas, do you have WebGL2 disabled?`,
+        'error',
+        'OK',
+      ));
+      renderer = dummyRenderer;
+    } else {
+      /* eslint-disable-next-line max-len */
+      const module = await import(/* webpackChunkName: "voxel" */ '../ui/Renderer3D');
+      const Renderer3D = module.default;
+      renderer = new Renderer3D(store);
+    }
   } else {
     renderer = new Renderer2D(store);
   }