1 files changed, 49 insertions, 0 deletions
diff --git a/src/Vivant/Shader.hs b/src/Vivant/Shader.hs
new file mode 100644
index 0000000..503d1b7
--- /dev/null
+++ b/src/Vivant/Shader.hs
@@ -0,0 +1,49 @@
+module Vivant.Shader (initShaders) where
+
+import           SDL (($=))
+import qualified Graphics.Rendering.OpenGL as GL
+import qualified Data.ByteString as BS
+import           System.Exit (exitFailure)
+import           System.IO (stderr, hPutStrLn)
+import           Control.Monad (unless)
+import           Paths_vivant (getDataDir)
+
+initShaders :: IO (GL.Program, GL.AttribLocation)
+initShaders = do
+    datadir <- getDataDir
+    -- compile vertex shader
+    vs <- GL.createShader GL.VertexShader
+    vsSource <- BS.readFile $ datadir <> "/shaders/triangle.vert"
+    GL.shaderSourceBS vs $= vsSource
+    GL.compileShader vs
+    vsOK <- GL.get $ GL.compileStatus vs
+    unless vsOK $ do
+        hPutStrLn stderr "Error in vertex shader\n"
+        exitFailure
+
+    -- Do it again for the fragment shader
+    fs <- GL.createShader GL.FragmentShader
+    fsSource <- BS.readFile $ datadir <> "/shaders/triangle.frag"
+    GL.shaderSourceBS fs $= fsSource
+    GL.compileShader fs
+    fsOK <- GL.get $ GL.compileStatus fs
+    unless fsOK $ do
+        hPutStrLn stderr "Error in fragment shader\n"
+        exitFailure
+
+    program <- GL.createProgram
+    GL.attachShader program vs
+    GL.attachShader program fs
+    GL.attribLocation program "coord2d" $= GL.AttribLocation 0
+    GL.linkProgram program
+    linkOK <- GL.get $ GL.linkStatus program
+    GL.validateProgram program
+    status <- GL.get $ GL.validateStatus program
+    unless (linkOK && status) $ do
+        hPutStrLn stderr "GL.linkProgram error"
+        plog <- GL.get $ GL.programInfoLog program
+        putStrLn plog
+        exitFailure
+    GL.currentProgram $= Just program
+
+    return (program, GL.AttribLocation 0)