GL: If GL version is too old, let the user know.

kivy/core/gl/__init__.py

@@ -6,9 +6,12 @@ Select and use the best OpenGL library available. Depending on your system, the
 core provider can select an OpenGL ES or a 'classic' desktop OpenGL library.
 '''
 
-# Right now, only PyOpenGL
 from os import environ
 
+
+MIN_REQUIRED_GL_VERSION = (2, 0)
+
+
 if 'KIVY_DOC' not in environ:
 
     from kivy.logger import Logger
@@ -21,7 +24,29 @@ if 'KIVY_DOC' not in environ:
         print_gl_version()
 
     def print_gl_version():
-        Logger.info('GL: OpenGL version <%s>' % str(glGetString(GL_VERSION)))
+        # As per http://www.opengl.org/resources/faq/technical/extensions.htm
+        # the format for the string is:
+        # """The first part of the return string must be of the form
+        # [major-number].[minor-number], optionally followed by a release
+        # number or other vendor-specific information.
+        version = str(glGetString(GL_VERSION))
+        try:
+            majorminor = version.split()[0]
+            major, minor = majorminor.split('.')
+        except:
+            # We don't want to bail out here if there is an error while parsing
+            # Just raise a warning (God knows what vendors return here...)
+            Logger.warning('GL: Error parsing OpenGL version: %s' % version)
+        else:
+            # If parsing went without problems, let the user know if his
+            # graphics hardware/drivers are too old
+            if (major, minor) < MIN_REQUIRED_GL_VERSION:
+                msg = 'GL: Minimum required OpenGL version (2.0) NOT found! ' \
+                      'Try upgrading your graphics drivers and/or your ' \
+                      'graphics hardware in case of problems.'
+                Logger.critical(msg)
+
+        Logger.info('GL: OpenGL version <%s>' % version)
         Logger.info('GL: OpenGL vendor <%s>' % str(glGetString(GL_VENDOR)))
         Logger.info('GL: OpenGL renderer <%s>' % str(glGetString(GL_RENDERER)))