From 6131427deae168419a31e5c30571ae234365e495 Mon Sep 17 00:00:00 2001
From: Luke Campagnola <luke.campagnola@gmail.com>
Date: Sat, 13 Jul 2013 16:06:48 -0400
Subject: [PATCH] added error message when GL shaders are not available

---
 pyqtgraph/opengl/shaders.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pyqtgraph/opengl/shaders.py b/pyqtgraph/opengl/shaders.py
index b1652850..5ef20776 100644
--- a/pyqtgraph/opengl/shaders.py
+++ b/pyqtgraph/opengl/shaders.py
@@ -1,3 +1,4 @@
+import OpenGL
 from OpenGL.GL import *
 from OpenGL.GL import shaders
 import re
@@ -218,6 +219,8 @@ class Shader(object):
         if self.compiled is None:
             try:
                 self.compiled = shaders.compileShader(self.code, self.shaderType)
+            except OpenGL.NullFunctionError:
+                raise Exception("This OpenGL implementation does not support shader programs; many features on pyqtgraph will not work.")
             except RuntimeError as exc:
                 ## Format compile errors a bit more nicely
                 if len(exc.args) == 3: