htanks/Render.hs

module Render ( setup
              , resize
              , render
              ) where


import Game
import Level
import Tank
import Texture

import Control.Monad.State

import Data.Fixed
import Data.Maybe
import Data.Ratio
import qualified Data.Map as M

import Bindings.GLPng

import Graphics.Rendering.OpenGL.GL (($=), GLfloat, GLdouble, Capability(..), Vector3(..))
import Graphics.Rendering.OpenGL.GL.BeginEnd (renderPrimitive, PrimitiveMode(..))
import Graphics.Rendering.OpenGL.GL.CoordTrans (matrixMode, MatrixMode(..), viewport, Position(..), Size(..), loadIdentity, ortho, translate, rotate)
import Graphics.Rendering.OpenGL.GL.Framebuffer (clear, ClearBuffer(..))
import Graphics.Rendering.OpenGL.GL.PerFragment (blend, blendFunc, BlendingFactor(..))
import Graphics.Rendering.OpenGL.GL.Texturing.Application (texture)
import Graphics.Rendering.OpenGL.GL.Texturing.Objects (textureBinding, TextureObject(..))
import Graphics.Rendering.OpenGL.GL.Texturing.Parameters (Repetition(..), Clamping(..), TextureFilter(..), MinificationFilter, MagnificationFilter)
import Graphics.Rendering.OpenGL.GL.Texturing.Specification (TextureTarget(..))
import Graphics.Rendering.OpenGL.GL.VertexSpec


texturePath :: Texture -> String
texturePath t
    | t == TextureWood = "tex/Wood.png"
    | t == TextureTank = "tex/Tank.png"

getTexture :: Texture -> Game TextureObject
getTexture t = do
  ts <- gets textures
  let tobj = M.lookup t ts
  
  if (isJust tobj)
      then
          return $ fromJust tobj
      else do
          tex <- liftIO $ pngBind (texturePath t) BuildMipmap Alpha (Repeated, Repeat) (Linear', Just Linear') Linear' >>= return . TextureObject . fromIntegral . fst
          modify $ \state -> state {textures = M.insert t tex ts}
          return tex
                                               

setup :: Int -> Int -> Game ()
setup w h = do
  resize w h
  liftIO $ do
    blend $= Enabled
    blendFunc $= (SrcAlpha, OneMinusSrcAlpha)
  
  -- cache textures
  getTexture TextureWood
  getTexture TextureTank
  
  return ()

resize :: Int -> Int -> Game ()
resize w h = do
  let wn = fromIntegral w
      hn = fromIntegral h
      aspect = fromReal (wn/hn)
  
  lvl <- gets level
  let s = max (0.5*(fromIntegral $ levelWidth lvl)/aspect) (0.5*(fromIntegral $ levelHeight lvl)) :: GLdouble
  
  liftIO $ do
    matrixMode $= Projection
    loadIdentity
    ortho (-s*aspect) (s*aspect) (-s) s (-1) 1
    
    matrixMode $= Modelview 0
    
    viewport $= ((Position 0 0), (Size (fromIntegral w) (fromIntegral h)))


render :: Game ()
render = do
  tank <- liftM head $ gets tanks
  let x = fromReal . posx $ tank
      y = fromReal . posy $ tank
  (lw, lh) <- gets level >>= \l -> return (fromIntegral . levelWidth $ l :: GLfloat, fromIntegral . levelHeight $ l :: GLfloat)
  
  textureWood <- getTexture TextureWood
  textureTank <- getTexture TextureTank
  
  liftIO $ do
           clear [ColorBuffer]
           
           loadIdentity
           
           texture Texture2D $= Enabled
           textureBinding Texture2D $= Just textureWood
           
           renderPrimitive Quads $ do
             texCoord $ TexCoord2 (0 :: GLfloat) (0 :: GLfloat)
             vertex $ Vertex2 (-0.5*lw) (-0.5*lh)
             
             texCoord $ TexCoord2 0 lw
             vertex $ Vertex2 (-0.5*lw) (0.5*lh)
             
             texCoord $ TexCoord2 lh lw
             vertex $ Vertex2 (0.5*lw) (0.5*lh)
             
             texCoord $ TexCoord2 lh (0 :: GLfloat)
             vertex $ Vertex2 (0.5*lw) (-0.5*lh)

           
           textureBinding Texture2D $= Just textureTank
           
           translate $ Vector3 x y (0 :: GLfloat)
           rotate (90 + (fromReal . dir $ tank)) $ Vector3 0 0 (1 :: GLfloat)
           
           renderPrimitive Quads $ do
             texCoord $ TexCoord2 (0 :: GLfloat) (0 :: GLfloat)
             vertex $ Vertex2 (-0.5 :: GLfloat) (-0.5 :: GLfloat)
             
             texCoord $ TexCoord2 (0 :: GLfloat) (1 :: GLfloat)
             vertex $ Vertex2 (-0.5 :: GLfloat) (0.5 :: GLfloat)
             
             texCoord $ TexCoord2 (1 :: GLfloat) (1 :: GLfloat)
             vertex $ Vertex2 (0.5 :: GLfloat) (0.5 :: GLfloat)
             
             texCoord $ TexCoord2 (1 :: GLfloat) (0 :: GLfloat)
             vertex $ Vertex2 (0.5 :: GLfloat) (-0.5 :: GLfloat)

fromReal :: (Real a, Fractional b) => a -> b
fromReal = fromRational . toRational