fix(webgl): webgl force context reload

Author: BryonLewis

src/vgl/renderWindow.js

@@ -126,9 +126,11 @@ vgl.renderWindow = function (canvas) {
    * Create the window.
    *
    * @param {vgl.renderState} renderState
+   * @param {boolean} forceContextChanged
+   *   If true, force a context change even if the context is the same as the old context.
    * @returns {boolean}
    */
-  this._setup = function (renderState) {
+  this._setup = function (renderState, forceContextChanged) {
     var oldContext = m_context;
     m_context = null;
 
@@ -138,6 +140,9 @@ vgl.renderWindow = function (canvas) {
       m_context = m_canvas.getContext('webgl') ||
             m_canvas.getContext('experimental-webgl');
       var didContextChange = !!oldContext && oldContext !== m_context;
+      if (forceContextChanged) {
+        didContextChange = true;
+      }
 
       // Set width and height of renderers if not set already
       var i;

src/webgl/webglRenderer.js

@@ -34,6 +34,7 @@ var webglRenderer = function (arg) {
       m_contextRenderer = null,
       m_viewer = null,
       m_lastZoom,
+      m_contextLost = false,
       m_updateCamera = false,
       s_init = this._init,
       s_exit = this._exit;
@@ -92,13 +93,19 @@ var webglRenderer = function (arg) {
     m_viewer.init();
     m_contextRenderer = m_viewer.renderWindow().activeRenderer();
     m_contextRenderer.setResetScene(false);
-    canvas.get(0).addEventListener('webglcontextlost', (evt) => evt.preventDefault(), false);
+    canvas.get(0).addEventListener('webglcontextlost', function (evt) {
+      m_contextLost = true;
+      evt.preventDefault();
+    }, false);
     canvas.get(0).addEventListener('webglcontextrestored', function () {
       if (!m_viewer) {
         return;
       }
+      m_contextLost = false;
       // Reinitialize GL objects, then force a camera sync before redraw.
-      m_viewer.renderWindow()._setup();
+      // While the context is lost and restored it could be the same context,
+      // so we need to force a context change for gpu resources to be re-created.
+      m_viewer.renderWindow()._setup(undefined, true);
       m_updateCamera = true;
       m_this._render();
     }, false);
@@ -162,6 +169,9 @@ var webglRenderer = function (arg) {
    */
   this._renderFrame = function () {
     if (m_viewer) {
+      if (m_contextLost) {
+        return;
+      }
       if (m_updateCamera) {
         m_updateCamera = false;
         m_this._updateRendererCamera();