Main.hs

-- Requires installation of SDL2 https://github.com/haskell-game/sdl2
-- and possibly GLUT https://hackage.haskell.org/package/GLUT

-- Using graphics code from https://wiki.haskell.org/OpenGLTutorial1
module Main (main) where

import Control.Monad
import Linear
import Data.StateVar
import Foreign.C.Types (CInt)
import qualified SDL
import Control.Monad.Loops
import qualified Graphics.Rendering.OpenGL as OpenGL
import Data.Text (Text)
import qualified Data.Text as Text

myVertices :: [OpenGL.Vertex3 OpenGL.GLfloat]
myVertices = [ OpenGL.Vertex3 (sin (2*pi*k/12)) (cos (2*pi*k/12)) 0 | k <- [1..12] ]

screenWidth, screenHeight :: CInt
(screenWidth, screenHeight) = (640, 480)

myWindowConfig :: SDL.WindowConfig
myWindowConfig = SDL.defaultWindow { SDL.windowInitialSize = V2 screenWidth screenHeight
                                   , SDL.windowGraphicsContext = SDL.OpenGLContext SDL.defaultOpenGL }

main :: IO ()
main = do
  SDL.initialize [SDL.InitVideo]
  SDL.HintRenderScaleQuality $= SDL.ScaleLinear
  window <- SDL.createWindow (Text.pack "SDL / OpenGL Example") myWindowConfig
  SDL.showWindow window
  SDL.glCreateContext window

  iterateWhile not $
    OpenGL.clear [OpenGL.ColorBuffer]
    >> OpenGL.renderPrimitive OpenGL.Points (mapM_ OpenGL.vertex myVertices)
    >> OpenGL.flush
    >> SDL.glSwapWindow window
    >> any ((== SDL.QuitEvent) . SDL.eventPayload) <$> unfoldM SDL.pollEvent

  SDL.destroyWindow window
  SDL.quit