renderer-tutorial/src/Main.hs

264 lines
7.1 KiB
Haskell

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE Strict #-}
module Main where
import SDL (($=), get)
import qualified SDL
import qualified SDL.Raw.Video as SDL (glSetAttribute)
import qualified SDL.Raw.Enum as SDL
import qualified Graphics.Rendering.OpenGL as GL
import qualified Graphics.GL as GLRaw
import Control.Concurrent.MVar
import Control.Monad
import Control.Monad.Loops
import Foreign hiding (void)
import Foreign.Ptr
import Foreign.Marshal.Array
import Foreign.Storable
import Data.Word
import qualified Data.ByteString as B
import qualified Data.ByteString.Char8 as B8
import qualified Data.List as L
import System.Random (randomRIO)
main :: IO ()
main = do
-- -- INITIALIZATION
-- Initialize all the things! (including wacky stuff like joysticks and so on)
SDL.initializeAll
-- create an actual window with OpenGL 3.3
window <- SDL.createWindow "renderer" (SDL.defaultWindow
{ SDL.windowGraphicsContext = SDL.OpenGLContext SDL.defaultOpenGL
{ SDL.glProfile = SDL.Core SDL.Normal 3 3
}
}
)
-- enable context sharing (this is not absolutely neccessary)
void $ SDL.glSetAttribute SDL.SDL_GL_SHARE_WITH_CURRENT_CONTEXT 1
-- create ancutal context
context <- SDL.glCreateContext window
-- window should be a window, not fullscreen or so
SDL.setWindowMode window SDL.Windowed
-- synchronize buffer swapping with monitor's vsync
SDL.swapInterval $= SDL.SynchronizedUpdates
-- show the window
SDL.showWindow window
-- print OpenGL version of active context
version <- peekArray0 (0 :: Word8) =<< GLRaw.glGetString GLRaw.GL_VERSION
print (B.pack version)
-- -- VERTICES
-- first, create and bind a vertex array object
bo <- GL.genObjectName
GL.bindVertexArrayObject $= Just bo
-- define vertices (positions of the triangle corners) as List of Floats
let vertexPositions =
[ (-0.5), (-0.5) -- 0
, 0.5 , (-0.5) -- 1
, 0.5 , 0.5 -- 2
, (-0.5), 0.5 -- 3
] :: [GL.GLfloat]
-- create draw order indices
indices = [0, 1, 2, 2, 3, 0] :: [GL.GLuint]
-- create and bind buffer for vertices
buf <- GL.genObjectName
GL.bindBuffer GL.ArrayBuffer $= Just buf
-- put vertices into the buffer
-- turn the list into a pointer
withArray vertexPositions $ \ptr ->
-- Feed the data to the buffer
GL.bufferData GL.ArrayBuffer $=
-- how much bytes of memory we are going to write (as an Int32)
( fromIntegral $ length vertexPositions * sizeOf (undefined :: GL.GLfloat)
-- The pointer to the data
, ptr
-- The data's usage
, GL.StaticDraw
)
-- enable and specify data layout of the in-memory vertices
GL.vertexAttribPointer (GL.AttribLocation 0) $=
( GL.ToFloat
, GL.VertexArrayDescriptor
-- There are 2 components (Floats) to our attribute
2
-- They are Floats
GL.Float
-- ???
0
-- our attribute is directly at the beginning of each vertex
(plusPtr nullPtr 0)
)
GL.vertexAttribArray (GL.AttribLocation 0) $= GL.Enabled
-- create and bind buffer index buffer
ibo <- GL.genObjectName
GL.bindBuffer GL.ElementArrayBuffer $= Just ibo
-- put indices into index buffer
-- turn the list into a pointer
withArray indices $ \ptr -> do
-- Feed the data to the buffer
GL.bufferData GL.ElementArrayBuffer $=
-- how much bytes of memory we are going to write (as an Int32)
( fromIntegral $ length indices * sizeOf (undefined :: GL.GLuint)
-- The pointer to the data
, ptr
-- The data's usage
, GL.StaticDraw
)
-- -- SHADERS
-- read in shaders from source file
vertSrc <- B.readFile "./res/shaders/vert.shader"
fragSrc <- B.readFile "./res/shaders/frag.shader"
sp <- createShaderProgram vertSrc fragSrc
GL.currentProgram $= Just sp
-- -- UNIFORMS
-- get the uniform's location out of the shader program
uniLoc <- get $ GL.uniformLocation sp "u_color"
-- write data to the uniform
GL.uniform uniLoc $= (GL.Color4 1 0.5 0 1 :: GL.Color4 GL.GLfloat)
err <- get GL.errors
print $ "pre-loop errors: " <> show err
-- -- EVENTING AND DRAWING
-- initial poll for events
evs <- newMVar =<< SDL.pollEvents
-- Loop running until window closes
whileM_ (notElem (SDL.WindowClosedEvent (SDL.WindowClosedEventData window))
<$> map SDL.eventPayload <$> readMVar evs) $ do
-- poll again
void $ swapMVar evs =<< SDL.pollEvents
-- -- OBEY THE HYPNOTOAD!
-- clearcol <- GL.Color4
-- <$> (randomRIO (0, 1))
-- <*> (randomRIO (0, 1))
-- <*> (randomRIO (0, 1))
-- <*> pure 1
-- GL.clearColor $= clearcol
-- clear buffers before drawing
GL.clear [GL.ColorBuffer]
-- the actual drawing happens here
void $ get GL.errors
GL.drawElements GL.Triangles 6 GL.UnsignedInt nullPtr
err <- get GL.errors
when (not $ null err) (print $ "loop errors: " <> show err)
-- make GL finish things up
-- GL.flush
-- draw context on screen
SDL.glSwapWindow window
-- -- CLEAN UP
-- wrapping things up
putStrLn "loop exited. shutting down."
-- delete context
SDL.glDeleteContext context
-- destroy window
SDL.destroyWindow window
-- quit SDL
SDL.quit
-- This is the end.
putStrLn "Bye!"
----------------------- Supplemantary functions -------------------------------
-- | create the actual Shader programs from source
createShaderProgram
:: B.ByteString -- ^ vertex shader source
-> B.ByteString -- ^ fragment shader source
-> IO GL.Program
createShaderProgram vertSrc fragSrc = do
-- create program Object
program <- GL.createProgram
-- create shaders from the source codes given
vs <- compileShaderSource GL.VertexShader vertSrc
fs <- compileShaderSource GL.FragmentShader fragSrc
-- attach, link and validate the shader program
GL.attachedShaders program $= [vs, fs]
GL.linkProgram program
GL.validateProgram program
ok <- get (GL.validateStatus program)
if ok
then
putStrLn "Shaderprogram linked successfully!"
else do
info <- get (GL.programInfoLog program)
putStrLn "Shaderprogram linking failed!\nInfo log says:"
putStrLn info
GL.deleteObjectName program
-- throw away the shaders, since they are linked into the shader program
mapM_ (\s -> GL.deleteObjectName s) [fs, vs]
return program
-- | compile a shader from source
compileShaderSource
:: GL.ShaderType -- ^ what type of shader we are compiling
-> B.ByteString -- ^ its source code
-> IO GL.Shader
compileShaderSource type_ source = do
-- create shader object of specified type
shaderObject <- GL.createShader type_
-- assign source code to shader object
GL.shaderSourceBS shaderObject $= source
-- actually compile the shader
GL.compileShader shaderObject
-- error handling
ok <- GL.compileStatus shaderObject
if ok
then
putStrLn (show type_ ++ ": compilation successfull!")
else do
info <- get (GL.shaderInfoLog shaderObject)
putStrLn (show type_ ++ ": compilation failed!\nInfo log says:")
putStrLn info
GL.deleteObjectName shaderObject
return shaderObject