module Graphics.Rendering.Rect.Backgrounds(Backgrounds(..), renderBackgrounds) where

import Graphics.Rendering.Rect.CSS.Backgrounds
import Graphics.Rendering.Rect.Types
import qualified Data.ByteString.Char8 as B8
import Linear (M44)
import Control.Monad.IO.Class (MonadIO(..))
import Data.Maybe (fromMaybe, listToMaybe)

baseFragmentShader = B8.pack $ unlines [
    "#version 330 core",
    "out vec4 fcolour;",
    "uniform vec4 colour;",
    "void main() { fcolour = colour; }"
  ]

renderBackgrounds :: (MonadIO m, MonadIO n) =>
    n (Backgrounds -> Rects -> M44 Float -> m ())
renderBackgrounds = do
    base <- renderRectWith baseFragmentShader ["colour"]
    return $ \self -> base [c $ background self] $ headDef borderBox $ clip self

headDef def = fromMaybe def . listToMaybe