Merge pull request #168 from ux3d/fix/webGlCheck

Detect WebGL 2 and report if not avialable (GSVN-363)

app_web/src/ui/ui.js

@@ -105,6 +105,14 @@ const app = new Vue({
         // remove input class from color picker (added by default by buefy)
         const colorPicker = document.getElementById("clearColorPicker");
         colorPicker.classList.remove("input");
+
+        // test if webgl is present
+        const context = canvas.getContext("webgl2", { alpha: false, antialias: true });
+        if (context === undefined || context === null) {
+            this.error("The sample viewer requires WebGL 2.0, which is not supported by this browser or device. " + 
+            "Please try again with another browser, or check https://get.webgl.org/webgl2/ " +
+            "if you believe you are seeing this message in error.", 15000);
+        }
     },
     methods:
     {
@@ -140,11 +148,11 @@ const app = new Vue({
                 type: 'is-warning'
             })
         },
-        error(message) {
+        error(message, duration = 5000) {
             this.$buefy.toast.open({
                 message: message,
                 type: 'is-danger',
-                duration: 5000
+                duration: duration
             })
         },
         goToLoadingState() {