1 files changed, 45 insertions, 0 deletions

diff --git a/Spear/GLSL/Error.hs b/Spear/GLSL/Error.hs
new file mode 100644
index 0000000..7865996
--- /dev/null
+++ b/Spear/GLSL/Error.hs
@@ -0,0 +1,45 @@
+module Spear.GLSL.Error
+(
+    getGLError
+,   printGLError
+,   assertGL
+)
+where
+
+
+import Spear.Setup
+
+import Graphics.Rendering.OpenGL.Raw.Core31
+import System.IO (hPutStrLn, stderr)
+
+
+-- | Get the last OpenGL error.
+getGLError :: IO (Maybe String)
+getGLError = fmap translate glGetError
+    where
+        translate err
+            | err == gl_NO_ERROR          = Nothing
+            | err == gl_INVALID_ENUM      = Just "Invalid enum"
+            | err == gl_INVALID_VALUE     = Just "Invalid value"
+            | err == gl_INVALID_OPERATION = Just "Invalid operation"
+            | err == gl_OUT_OF_MEMORY     = Just "Out of memory"
+            | otherwise                   = Just "Unknown error"
+
+
+-- | Print the last OpenGL error.
+printGLError :: IO ()
+printGLError = getGLError >>= \err -> case err of
+    Nothing  -> return ()
+    Just str -> hPutStrLn stderr str
+
+
+-- | Run the given 'Setup' action and check for OpenGL errors.
+-- If an OpenGL error is produced, an exception is thrown
+-- containing the given string and the OpenGL error.
+assertGL :: Setup a -> String -> Setup a
+assertGL action err = do
+    result <- action
+    status <- setupIO getGLError
+    case status of
+        Just str -> setupError $ "OpenGL error raised: " ++ err ++ "; " ++ str
+        Nothing  -> return result