use preserveDrawingBuffer in gl tests to make them work on latest firefox

2 files changed, 7 insertions, 1 deletions

diff --git a/src/library_browser.js b/src/library_browser.js
index e9396d69..5b19a360 100644
--- a/src/library_browser.js
+++ b/src/library_browser.js
@@ -204,7 +204,12 @@ mergeInto(LibraryManager.library, {
       var ctx;
       try {
         if (useWebGL) {
-          ctx = canvas.getContext('experimental-webgl', { alpha: false });
+          ctx = canvas.getContext('experimental-webgl', {
+            alpha: false,
+#if GL_TESTING
+            preserveDrawingBuffer: true
+#endif
+          });
         } else {
           ctx = canvas.getContext('2d');
         }
diff --git a/src/settings.js b/src/settings.js
index df9da926..7caa5b92 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -158,6 +158,7 @@ var SOCKET_DEBUG = 0; // Log out socket/network data transfer.
 
 var GL_DEBUG = 0; // Print out all calls into WebGL. As with LIBRARY_DEBUG, you can set a runtime
                   // option, in this case GL.debug.
+var GL_TESTING = 0; // When enabled, sets preserveDrawingBuffer in the context, to allow tests to work (but adds overhead)
 var GL_MAX_TEMP_BUFFER_SIZE = 2097152; // How large GL emulation temp buffers are
 var GL_UNSAFE_OPTS = 1; // Enables some potentially-unsafe optimizations in GL emulation code