flip image at loading, not in shader

renderer-tutorial.cabal

@@ -29,6 +29,7 @@ executable renderer-tutorial
                      , monad-loops
                      , random
                      , JuicyPixels
+                     , JuicyPixels-extra
   other-modules:       BindableClass
                      , BufferClass
                      , VertexBuffer

res/shaders/vert.shader

@@ -8,5 +8,5 @@ out vec2 v_texCoord;
 void main()
 {
   gl_Position = vec4(position, 1);
-  v_texCoord = vec2(texCoord.x, 1.0 - texCoord.y);
+  v_texCoord = texCoord;
 }

shell.nix

@@ -4,8 +4,9 @@ let
 
   inherit (nixpkgs) pkgs;
 
-  f = { mkDerivation, base, bytestring, JuicyPixels, linear
-      , monad-loops, OpenGL, OpenGLRaw, random, sdl2, stdenv, vector
+  f = { mkDerivation, base, bytestring, JuicyPixels
+      , JuicyPixels-extra, linear, monad-loops, OpenGL, OpenGLRaw, random
+      , sdl2, stdenv, vector
       }:
       mkDerivation {
         pname = "renderer-tutorial";
@@ -14,8 +15,8 @@ let
         isLibrary = false;
         isExecutable = true;
         executableHaskellDepends = [
-          base bytestring JuicyPixels linear monad-loops OpenGL OpenGLRaw
-          random sdl2 vector
+          base bytestring JuicyPixels JuicyPixels-extra linear monad-loops
+          OpenGL OpenGLRaw random sdl2 vector
         ];
         license = stdenv.lib.licenses.gpl3;
       };

src/Texture.hs

@@ -5,6 +5,7 @@ import SDL (($=), get)
 import qualified Graphics.Rendering.OpenGL as GL
 
 import Codec.Picture
+import Codec.Picture.Extra
 
 import Data.Either
 
@@ -40,7 +41,7 @@ newTexture :: FilePath -> GL.GLuint -> IO Texture
 newTexture fp slot = do
 
   -- read in image from filesystem
-  img <- convertRGBA8 <$>
+  img <- flipVertically <$> convertRGBA8 <$>
     either (error $ "reading image file " <> fp <> " failed!") id <$>
     readImage fp