we can haz GUI?

we can.

src/Main.hs

@@ -5,8 +5,8 @@ import Data.Int (Int8)
 import Graphics.Rendering.OpenGL.GL.Texturing.Specification (TextureSize2D)
 import Graphics.Rendering.OpenGL.GL.PixelRectangles.ColorTable (PixelInternalFormat(..))
 import Graphics.Rendering.OpenGL.GL.Texturing.Specification (texImage2D)
-import Foreign.Marshal.Array (pokeArray)
 import Control.Monad (liftM)
+import Foreign.Marshal.Array (pokeArray)
 import Foreign.Marshal.Alloc (allocaBytes)
 import Graphics.Rendering.OpenGL.GL.Texturing.Parameters (textureFilter)
 import Graphics.Rendering.OpenGL.GL.Texturing.Specification (TextureTarget2D(Texture2D))
@@ -53,7 +53,8 @@ import Graphics.Rendering.OpenGL.Raw.ARB.TessellationShader
 import           Map.Map
 import           Render.Misc                          (checkError,
                                                        createFrustum, getCam,
-                                                       curb, tryWithTexture)
+                                                       curb, tryWithTexture,
+                                                       genColorData)
 import           Render.Render                        (initRendering,
                                                        initMapShader,
                                                        initHud)
@@ -191,7 +192,7 @@ main = do
                         {
                         }
               , _ui                  = UIState
-                        {
+                        { _uiHasChanged        = True
                         }
               }
 
@@ -227,7 +228,10 @@ draw = do
         tessFac  = state ^. gl.glMap.stateTessellationFactor
         window   = env ^. windowObject
         rb       = state ^. gl.glRenderbuffer
+    if state ^. ui.uiHasChanged then
         prepareGUI
+    else
+        return ()
     liftIO $ do
         --bind renderbuffer and set sample 0 as target
         --GL.bindRenderbuffer GL.Renderbuffer GL.$= rb
@@ -470,7 +474,7 @@ adjustWindow = do
                    allocaBytes (fbWidth*fbHeight*4) $ \ptr -> do
                                                                --default to ugly pink to see if
                                                                --somethings go wrong.
-                        let imData = take (fbWidth*fbHeight*4) (cycle [255,0,255,0] :: [Int8])
+                        let imData = genColorData (fbWidth*fbHeight) [255,0,255,0]
                         --putStrLn $ show imData
                         pokeArray ptr imData
                         -- HUD
@@ -486,6 +490,7 @@ adjustWindow = do
                    checkError "setting up HUD-Tex"
                    return renderBuffer
     modify $ gl.glRenderbuffer .~ rb
+    modify $ ui.uiHasChanged .~ True
 
 processEvents :: Pioneers ()
 processEvents = do

src/Render/Misc.hs

@@ -3,6 +3,7 @@ module Render.Misc where
 
 import           Control.Monad
 import qualified Data.ByteString                            as B (ByteString)
+import           Data.Int                                   (Int8)
 import           Graphics.Rendering.OpenGL.GL.Shaders
 import           Graphics.Rendering.OpenGL.GL.StateVar
 import           Graphics.Rendering.OpenGL.GL.StringQueries
@@ -125,3 +126,8 @@ tryWithTexture t f fail' =
                 Just tex -> f tex
                 _ -> fail'
 
+genColorData ::      Int  -- ^ Amount
+                -> [Int8] -- ^ [r,g,b,a], [r,g,b] - whatever should be repeatet.
+                -> [Int8]
+genColorData n c = take ((length c)*n) (cycle c)
+

src/Types.hs

@@ -109,7 +109,7 @@ data GLState = GLState
     }
 
 data UIState = UIState
-    {
+    { _uiHasChanged        :: !Bool
     }
 
 data State = State

src/UI/Callbacks.hs

@@ -6,6 +6,14 @@ import Control.Monad.Trans (liftIO)
 import Types
 import UI.UITypes
 
+import qualified Graphics.Rendering.OpenGL.GL         as GL
+import           Control.Lens                         ((^.), (.~), (%~))
+import           Render.Misc                          (genColorData)
+import           Foreign.Marshal.Array (pokeArray)
+import           Foreign.Marshal.Alloc (allocaBytes)
+import           Control.Monad.RWS.Strict             (get, liftIO, modify)
+
+
 data Pixel = Pixel Int Int
 
 getGUI :: [GUIAny]
@@ -47,12 +55,48 @@ alternateClickHandler :: Pixel -> Pioneers ()
 alternateClickHandler (Pixel x y) = liftIO $ putStrLn $ unwords ["alternate press on (",show x,",",show y,")"]
 
 
--- | informs the GUI to prepare a blitting of state ^. gl.hudTexture
+-- | informs the GUI to prepare a blitting of state ^. gl.glHud.hudTexture
 --
 --TODO: should be done asynchronously at one point.
+--        -> can't. if 2 Threads bind Textures its not sure
+--           on which one the GPU will work.
+--           "GL.textureBinding GL.Texture2D" is a State set
+--           to the texture all following works on.
+--
+--           https://www.opengl.org/wiki/GLAPI/glTexSubImage2D for copy
 prepareGUI :: Pioneers ()
 prepareGUI = do
-                return ()
+                state <- get
+                let tex = (state ^. gl.glHud.hudTexture)
+                liftIO $ do
+                    -- bind texture - all later calls work on this one.
+                    GL.textureBinding GL.Texture2D GL.$= Just tex
+                    mapM_ (copyGUI tex) getGUI
+                modify $ ui.uiHasChanged .~ False
+
+--TODO: Perform border-checking ... is xoff + width and yoff+height inside the screen-coordinates..
+copyGUI :: GL.TextureObject -> GUIAny -> IO ()
+copyGUI tex widget = do
+                        let (xoff, yoff, width, height) = getBoundary widget
+                            int = fromInteger.toInteger --conversion between Int8, GLInt, Int, ...
+                            --temporary color here. lateron better some getData-function to
+                            --get a list of pixel-data or a texture.
+                            color = case widget of
+                                (GUIAnyC _)   -> [255,0,0,128]
+                                (GUIAnyB _ _) -> [255,255,0,255]
+                                (GUIAnyP _)   -> [128,128,128,255]
+                                _             -> [255,0,255,255]
+                        allocaBytes (width*height*4) $ \ptr -> do
+                                --copy data into C-Array
+                                pokeArray ptr (genColorData (width*height) color)
+                                GL.texSubImage2D
+                                        GL.Texture2D
+                                        0
+                                        (GL.TexturePosition2D (int xoff) (int yoff))
+                                        (GL.TextureSize2D (int width) (int height))
+                                        (GL.PixelData GL.RGBA GL.UnsignedByte ptr)
+                        mapM_ (copyGUI tex) (getChildren widget)
+copyGUI _ _ = return ()
 
 --TODO: Add scroll-Handler, return (Pioneers Bool) to indicate event-bubbling etc.
 --TODO: Maybe queues are better?