finished episode 27

src/Scenes/Texture2D.hs

@@ -97,10 +97,6 @@ instance SceneClass Texture2D where
       [ ShaderSource GL.VertexShader "./res/shaders/vert.shader"
       , ShaderSource GL.FragmentShader "./res/shaders/frag.shader"
       ]
-      [ "u_color"
-      , "u_texture"
-      , "u_mvp"
-      ]
     bind sp
     setUniform sp "u_texture" (texSlot tex)
 

src/Shader.hs

@@ -16,6 +16,8 @@ import qualified Data.ByteString as B
 
 import Data.Maybe (fromJust)
 
+import Control.Concurrent.MVar
+
 import Linear
 
 import Foreign.Marshal.Utils (with)
@@ -28,7 +30,7 @@ import BindableClass
 data Shader = Shader
   { shaderId :: GL.Program
   , shaderSources  :: [ShaderSource]
-  , shaderUniforms :: [ShaderUniform]
+  , shaderUniforms :: MVar [ShaderUniform]
   }
 
 -- make Shader Bindable
@@ -75,8 +77,8 @@ isRowMajor :: GL.MatrixOrder -> GL.GLboolean
 isRowMajor p = if (GL.RowMajor == p) then 1 else 0
 
 -- create new data object of type Shader
-newShader :: [ShaderSource] -> [String] -> IO Shader
+newShader :: [ShaderSource] -> IO Shader
-newShader shaderSrc uniforms = do
+newShader shaderSrc = do
   -- create program Object
   program <- GL.createProgram
 
@@ -110,27 +112,37 @@ newShader shaderSrc uniforms = do
   -- throw away the shaders, since they are linked into the shader program
   mapM_ (\s -> GL.deleteObjectName s) (map snd compilates)
 
-  -- retrieve locations of all uniforms and store them
-  uniLocs <- mapM
-    (\name -> do
-      loc <- get $ GL.uniformLocation program name
-      return (ShaderUniform name loc)
-      )
-    uniforms
-
   -- return data object
-  return (Shader program shaderSrc uniLocs)
+  Shader program shaderSrc <$> newMVar []
 
 -- pass uniform values into Shader program
 setUniform :: (GL.Uniform a) => Shader -> String -> a -> IO ()
-setUniform shader uniname data_ = do
+setUniform (Shader shaderProgram _ shaderUniforms) uniname data_ = do
-  -- retrieve uniform location
+  -- check if uniform location is already cached
-  let [ShaderUniform _ loc] = filter
+  locs <- readMVar shaderUniforms
-        (\(ShaderUniform name _) -> name == uniname)
-        (shaderUniforms shader)
 
-  -- set the data
+  -- retrieve uniform location
-  GL.uniform loc $= data_
+  let unilocs = filter
+        (\(ShaderUniform name _) -> name == uniname)
+        locs
+
+  case unilocs of
+    [] -> do
+      print ("Unknown uniform: " <> uniname)
+      print "Retrieving uniform location from shader program"
+      loc@(GL.UniformLocation locNum) <- get $ GL.uniformLocation shaderProgram uniname
+      if locNum < 0
+      then
+        print ("Uniform does not exist in shader program: " <> uniname)
+      else do
+        -- set the data
+        GL.uniform loc $= data_
+        -- add uniform to cache
+        modifyMVar_ shaderUniforms
+          (\list -> return $ ShaderUniform uniname loc : list)
+    [ShaderUniform _ loc] ->
+        -- set the data
+        GL.uniform loc $= data_
 
 -- | compile a shader from source
 compileShaderSource