add changelog; see changelog <3

1 files changed, 89 insertions, 0 deletions

diff --git a/src/Game/Internal/LoadShaders.hs b/src/Game/Internal/LoadShaders.hs
new file mode 100644
index 0000000..ded2da9
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+++ b/src/Game/Internal/LoadShaders.hs
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+--------------------------------------------------------------------------------
+-- |
+-- Module      :  LoadShaders
+-- Copyright   :  (c) Sven Panne 2013
+-- License     :  BSD3
+--
+-- Maintainer  :  Sven Panne <svenpanne@gmail.com>
+-- Stability   :  stable
+-- Portability :  portable
+--
+-- Utilities for shader handling, adapted from LoadShaders.cpp which is (c) The
+-- Red Book Authors.
+--
+--------------------------------------------------------------------------------
+
+module Game.Internal.LoadShaders (
+   ShaderSource(..), ShaderInfo(..), loadShaders
+) where
+
+import Control.Exception
+import Control.Monad
+import qualified Data.ByteString as B
+import Graphics.Rendering.OpenGL
+
+--------------------------------------------------------------------------------
+
+-- | The source of the shader source code.
+
+data ShaderSource =
+     ByteStringSource B.ByteString
+     -- ^ The shader source code is directly given as a 'B.ByteString'.
+   | StringSource String
+     -- ^ The shader source code is directly given as a 'String'.
+   | FileSource FilePath
+     -- ^ The shader source code is located in the file at the given 'FilePath'.
+   deriving ( Eq, Ord, Show )
+
+getSource :: ShaderSource -> IO B.ByteString
+getSource (ByteStringSource bs) = return bs
+getSource (StringSource str) = return $ packUtf8 str
+getSource (FileSource path) = B.readFile path
+
+--------------------------------------------------------------------------------
+
+-- | A description of a shader: The type of the shader plus its source code.
+
+data ShaderInfo = ShaderInfo ShaderType ShaderSource
+   deriving ( Eq, Ord, Show )
+
+--------------------------------------------------------------------------------
+
+-- | Create a new program object from the given shaders, throwing an
+-- 'IOException' if something goes wrong.
+
+loadShaders :: [ShaderInfo] -> IO Program
+loadShaders infos =
+   createProgram `bracketOnError` deleteObjectName $ \program -> do
+      loadCompileAttach program infos
+      linkAndCheck program
+      return program
+
+linkAndCheck :: Program -> IO ()
+linkAndCheck = checked linkProgram linkStatus programInfoLog "link"
+
+loadCompileAttach :: Program -> [ShaderInfo] -> IO ()
+loadCompileAttach _ [] = return ()
+loadCompileAttach program (ShaderInfo shType source : infos) =
+   createShader shType `bracketOnError` deleteObjectName $ \shader -> do
+      src <- getSource source
+      shaderSourceBS shader $= src
+      compileAndCheck shader
+      attachShader program shader
+      loadCompileAttach program infos
+
+compileAndCheck :: Shader -> IO ()
+compileAndCheck = checked compileShader compileStatus shaderInfoLog "compile"
+
+checked :: (t -> IO ())
+        -> (t -> GettableStateVar Bool)
+        -> (t -> GettableStateVar String)
+        -> String
+        -> t
+        -> IO ()
+checked action getStatus getInfoLog message object = do
+   action object
+   ok <- get (getStatus object)
+   unless ok $ do
+      infoLog <- get (getInfoLog object)
+      fail (message ++ " log: " ++ infoLog)