butterflies (empty) → 0.3.0.1

raw patch · 13 files changed

+1271/−0 lines, 13 filesdep +GLUTdep +OpenGLRawdep +OpenGLRaw21setup-changedbinary-added

Dependencies added: GLUT, OpenGLRaw, OpenGLRaw21, base, butterflies, bytestring, gl-capture, repa, repa-devil

Files

Geometry/Class.hs +15/−0
Geometry/Flat/ThreeD/Space.hs +46/−0
Geometry/Flat/TwoD/Space.hs +48/−0
Geometry/Flat/TwoD/Tessellation/Triangular.hs +68/−0
Geometry/Hyperbolic/TwoD/HalfSpace.hs +109/−0
Geometry/Utils.hs +10/−0
LICENSE +675/−0
README +28/−0
Setup.hs +2/−0
butterflies.cabal +55/−0
data/butterfly.png binary
data/palette.png binary
flat/Main.hs +215/−0

+ Geometry/Class.hs view

@@ -0,0 +1,15 @@+{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies #-}+module Geometry.Class where++class Geometry point geodesic | point -> geodesic, geodesic -> point where+  distance :: point -> point -> Double+  angle :: point -> point -> point -> Double+  geodesic :: point -> point -> geodesic+  rotate :: Double -> point -> point -> point+  translate :: Double -> geodesic -> point -> point+  midpoint :: point -> point -> point+  midpoint p q = translate (distance p q / 2) (geodesic p q) p++class Embedding model point where+  embed :: point -> model+  model :: model -> Maybe point

+ Geometry/Flat/ThreeD/Space.hs view

@@ -0,0 +1,46 @@+{-# LANGUAGE MultiParamTypeClasses #-}+module Geometry.Flat.ThreeD.Space+  ( Point(..)+  , Geodesic(..)+  ) where++import Geometry.Class+import qualified Geometry.Flat.TwoD.Space as E++data Point = Point{ pX, pY, pZ :: !Double } deriving Show+data Geodesic = Geodesic{ gO :: !Point, gX, gY, gZ :: !Double } deriving Show+  +instance Geometry Point Geodesic where++  distance (Point u v w) (Point x y z) =+    let dx = x - u+        dy = y - v+        dz = z - w+    in  sqrt (dx * dx + dy * dy + dz * dz)++  angle _ _ _ = error "Geometry.Flat.ThreeD.Space.angle"++  geodesic p@(Point u v w) (Point x y z) =+    let dx = x - u+        dy = y - v+        dz = z - w+        d = sqrt (dx * dx + dy * dy + dz * dz)+    in  Geodesic p (dx / d) (dy / d) (dz / d)++  rotate _ _ _ = error "Geometry.Flat.ThreeD.Space.rotate"++  translate d (Geodesic _ dx dy dz) (Point x y z) =+    Point (x + d * dx) (y + d * dy) (z + d * dz)++  midpoint (Point u v w) (Point x y z) =+    Point (0.5 * (u + x)) (0.5 * (v + y)) (0.5 * (w + z))++instance Embedding Point Point where+  embed = id+  model = Just++instance Embedding Point E.Point where+  embed (E.Point x y) = Point x y 0+  model (Point x y z)+    | z == 0 = Just (E.Point x y)+    | otherwise = Nothing

+ Geometry/Flat/TwoD/Space.hs view

@@ -0,0 +1,48 @@+{-# LANGUAGE MultiParamTypeClasses #-}+module Geometry.Flat.TwoD.Space+  ( Point(..)+  , Geodesic(..)+  ) where++import Geometry.Class+import Geometry.Utils (fixAngle)++data Point = Point{ pX, pY :: !Double } deriving Show+data Geodesic = Geodesic{ gO :: !Point, gX, gY :: !Double } deriving Show+  +instance Geometry Point Geodesic where++  distance (Point u v) (Point x y) =+    let dx = x - u+        dy = y - v+    in  sqrt (dx * dx + dy * dy)++  angle (Point p q) (Point u v) (Point x y) =+    let du = u - p+        dv = v - q+        dx = x - p+        dy = y - q+        uv = atan2 dv du+        xy = atan2 dy dx+    in  fixAngle (xy - uv)++  geodesic p@(Point u v) (Point x y) =+    let dx = x - u+        dy = y - v+        d = sqrt (dx * dx + dy * dy)+    in  Geodesic p (dx / d) (dy / d)++  rotate a (Point u v) (Point x y) =+    let co = cos a+        si = sin a+        p = x - u+        q = y - v+    in  Point (u + co * p - si * q) (v + si * p + co * q)++  translate d (Geodesic _ dx dy) (Point x y) = Point (x + d * dx) (y + d * dy)++  midpoint (Point u v) (Point x y) = Point (0.5 * (u + x)) (0.5 * (v + y))++instance Embedding Point Point where+  embed = id+  model = Just

+ Geometry/Flat/TwoD/Tessellation/Triangular.hs view

@@ -0,0 +1,68 @@+module Geometry.Flat.TwoD.Tessellation.Triangular+  ( tessellate+  , Triangle(..)+  , Vertex(..)+  ) where++import Geometry.Flat.TwoD.Space++data Triangle a = Triangle a a a deriving Show++data Vertex = Vertex{ vPos, vTex :: !Point, vSpots, vWings, vBody :: !Double }+  deriving Show++tessellate :: Int -> Int -> Double -> Point -> Point -> [Triangle Vertex]+tessellate p q s (Point lx ly) (Point hx hy) =+  let t = s * sqrt 3 / 2+      y = floor (ly / t)+      x = floor (lx / s)+      w = ceiling ((hx - lx) / s)+      h = ceiling ((hy - ly) / t)+      g = grid p q+      pc u v = (Point (s * (fromIntegral u + fromIntegral v / 2)) (t * fromIntegral v), g u v)+      b (p0@(Point x0 y0), h0) (Point x1 y1, h1) (Point x2 y2, h2) =+        let pTL = p0+            pTM = Point ((2 * x0 + x1) / 3) ((2 * y0 + y1) / 3)+            pTR = Point ((x0 + 2 * x1) / 3) ((y0 + 2 * y1) / 3)+            pBL = Point ((2 * x0 + x2) / 3) ((2 * y0 + y2) / 3)+            pBR = Point ((x0 + x1 + x2) / 3) ((y0 + y1 + y2) / 3)+            tTL = Point 0    1+            tTM = Point 0.5  1+            tTR = Point 1    1+            tBL = Point 0.25 0+            tBR = Point 0.75 0+            v pp tt = Vertex pp tt h0 h2 h1+            vTL = v pTL tTL+            vTM = v pTM tTM+            vTR = v pTR tTR+            vBL = v pBL tBL+            vBR = v pBR tBR+        in  [ Triangle vTL vTM vBL+            , Triangle vTM vTR vBR+            , Triangle vBL vTM vBR+            ]+      bs v0 v1 v2 = concat+        [ b v0 v1 v2+        , b v1 v2 v0+        , b v2 v0 v1+        ]+      tris u v = concat+        [ bs (pc u v) (pc (u+1) v) (pc u (v+1))+        , bs (pc (u+1) v) (pc (u+1) (v+1)) (pc u (v+1))+        ]+  in  concat+        [ tris (u - z) v+        | v <- [y .. y + h]+        , let z = (v + 1) `div` 2+        , u <- [x .. x + w]+        ]++grid :: Int -> Int -> Int -> Int -> Double+grid p q =+  let n = p * p + q * q + p * q+      i = p `gcd` q+      j = n `div` i+      o = head [ o' | o' <- [0 .. j - 1], (p + q) `mod` j == (o' * i * (q `div` i)) `mod` j ]+  in \x y ->+        let d = i * (y `div` i)+        in  fromIntegral (((x + o * d) `mod` j) + j * (y `mod` i))

+ Geometry/Hyperbolic/TwoD/HalfSpace.hs view

@@ -0,0 +1,109 @@+{-# LANGUAGE MultiParamTypeClasses #-}+module Geometry.Hyperbolic.TwoD.HalfSpace+  ( Point(..)+  , Geodesic(..)+  ) where++import Data.Fixed (mod')++import Geometry.Class+import qualified Geometry.Flat.TwoD.Space as E++data Point = Point{ pX, pY :: !Double } deriving Show++data Geodesic+  = Line{ gDir :: !Bool, gCX :: !Double }+  | Arc { gDir :: !Bool, gCX :: !Double, gR :: !Double }+  deriving Show++instance Geometry Point Geodesic where++  distance p q = case geodesic p q of+    Line{}  -> abs (log (pY p / pY q))+    g@Arc{} ->+      let a = gCX g - gR g+          b = gCX g + gR g+          pa = sqrt ((pX p - a) * (pX p - a) + pY p * pY p)+          pb = sqrt ((pX p - b) * (pX p - b) + pY p * pY p)+          qa = sqrt ((pX q - a) * (pX q - a) + pY q * pY q)+          qb = sqrt ((pX q - b) * (pX q - b) + pY q * pY q)+      in  abs (log ((pa / pb) / (qa / qb)))++  angle _ _ _ = error "Geometry.Hyperbolic.TwoD.HalfPlane.angle"++  geodesic p q+    | abs (pX p - pX q) < eps =+            Line{ gCX = 0.5 * (pX p + pX q), gDir = pY p < pY q }+    | otherwise =+        let cx = 0.5 * (pX q * pX q + pY q * pY q - pX p * pX p - pY p * pY p) / (pX q - pX p)+            r = sqrt ((pX p - cx) * (pX p - cx) + pY p * pY p)+        in  Arc{ gCX = cx, gDir = pX p < pX q, gR = r }++  rotate a p q =+    let g = geodesic p q+        b = angleAt g p+        h = fromPointAngle p (b + a)+        d = distance p q+    in  translate d h p++  translate d g p = atDist g p (abs d) (d >= 0)++instance Embedding Point Point where+  embed = id+  model = Just++instance Embedding E.Point Point where+  embed (Point x y) = E.Point x y+  model (E.Point x y)+    | y > 0     = Just (Point x y)+    | otherwise = Nothing++eps :: Double+eps = 1e-12++atParam :: Geodesic -> Double -> Point+atParam g@Line{} t = Point (gCX g) t+atParam g@Arc {} t = Point (gR g * cos (pi - t) + gCX g) (gR g * sin t)++paramAt :: Geodesic -> Point -> Double+paramAt   Line{} p = pY p+paramAt g@Arc {} p = pi - atan2 (pY p) (pX p - gCX g)++angleAt :: Geodesic -> Point -> Double+angleAt g@Line{} _ = (if gDir g then (subtract pi) else id) (pi/2)+angleAt g@Arc {} p = (if gDir g then (pi +) else id) (atan2 (pY p) (pX p - gCX g) + pi/2)++fromPointAngle :: Point -> Double -> Geodesic+fromPointAngle p a+  | abs ((a `mod'` pi) - pi/2) < eps =+          Line{ gCX = pX p, gDir = cos a >= 0 }+  | otherwise =+      let b = a + pi/2+          co = cos b+          si = sin b+          r = abs (pY p / si)+          cx = -(pY p * co - pX p * si) / si+      in  Arc{ gCX = cx, gDir = cos a >= 0, gR = r }++atDist :: Geodesic -> Point -> Double -> Bool -> Point+atDist g@Line{} p d dir+  | dir /= gDir g = binarySearch g p d (0 + eps) pp  (<)+  | otherwise     = binarySearch g p d pp (pp * 100) (>)+  where pp = paramAt g p+atDist g@Arc {} p d dir+  | dir /= gDir g = binarySearch g p d (0 + eps) pp  (<)+  | otherwise     = binarySearch g p d pp (pi - eps) (>)+  where pp = paramAt g p++binarySearch :: Geodesic -> Point -> Double -> Double -> Double -> (Double -> Double -> Bool) -> Point+binarySearch g p d lo0 hi0 cmp = go lo0 hi0+  where+    go lo hi =+      let mid = 0.5 * (lo + hi)+          q = atParam g mid+          m = distance p q+      in  if hi - lo < eps+            then q+            else if m `cmp` d+                    then go lo mid+                    else go mid hi

+ Geometry/Utils.hs view

@@ -0,0 +1,10 @@+module Geometry.Utils+  ( fixAngle+  ) where++import Data.Fixed (mod')++fixAngle :: Double -> Double+fixAngle a =+  let b = a `mod'` (2 * pi)+  in  if b > pi then b - 2 * pi else b

+ LICENSE view

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+ README view

@@ -0,0 +1,28 @@+butterflies -- butterfly tilings+Copyright (C) 2013  Claude Heiland-Allen <claude@mathr.co.uk>++This program is free software: you can redistribute it and/or modify+it under the terms of the GNU General Public License as published by+the Free Software Foundation, either version 3 of the License, or+(at your option) any later version.++This program is distributed in the hope that it will be useful,+but WITHOUT ANY WARRANTY; without even the implied warranty of+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the+GNU General Public License for more details.++You should have received a copy of the GNU General Public License+along with this program.  If not, see <http://www.gnu.org/licenses/>.+++Example usage:++  #!/bin/bash+  for s in $(seq 2 5)+  do+    for p in $(seq 0 $((s/2)))+    do+      q=$((s-p))+      butterflies-flat $q $p -geometry 1024x1024+    done+  done

+ Setup.hs view

@@ -0,0 +1,2 @@+import Distribution.Simple+main = defaultMain

+ butterflies.cabal view

@@ -0,0 +1,55 @@+name:                butterflies+version:             0.3.0.1+synopsis:            butterfly tilings+description:         various tilings with butterflies (after M C Escher 1950)+homepage:            http://code.mathr.co.uk/butterflies+license:             GPL-3+license-file:        LICENSE+author:              Claude Heiland-Allen+maintainer:          claude@mathr.co.uk+copyright:           (C) 2013,2015  Claude Heiland-Allen <claude@mathr.co.uk>+category:            Graphics+build-type:          Simple+cabal-version:       >=1.8++extra-source-files:  README+data-dir:            data+data-files:+  butterfly.png+  palette.png++library+  exposed-modules:+    Geometry.Class+    Geometry.Flat.ThreeD.Space+    Geometry.Flat.TwoD.Space+    Geometry.Flat.TwoD.Tessellation.Triangular+    Geometry.Hyperbolic.TwoD.HalfSpace+    Geometry.Utils+  build-depends:+    base ==4.8.*++executable butterflies-flat+  hs-source-dirs:      flat+  main-is:             Main.hs+  other-modules:+    Paths_butterflies+  build-depends:+    base ==4.8.*,+    bytestring ==0.10.*,+    OpenGLRaw ==2.6.*,+    OpenGLRaw21 ==2.0.*,+    GLUT ==2.7.*,+    gl-capture ==0.1.*,+    repa ==3.4.*,+    repa-devil ==0.3.*,+    butterflies ==0.3.0.1++source-repository head+  type:     git+  location: http://code.mathr.co.uk/butterflies.git++source-repository this+  type:     git+  location: http://code.mathr.co.uk/butterflies.git+  tag:      v0.3.0.1

+ data/butterfly.png view

binary file changed (absent → 31132 bytes)

+ data/palette.png view

binary file changed (absent → 241 bytes)

+ flat/Main.hs view

@@ -0,0 +1,215 @@+{-# LANGUAGE TypeSynonymInstances #-}+module Main (main) where++import Control.Monad (when)+import Foreign (Ptr, nullPtr, castPtr, plusPtr, advancePtr, allocaBytes, with, withArray, peek, poke, pokeByteOff)+import Foreign.C (CUChar)+import Foreign.C.String (withCString, peekCString)+import Foreign.ForeignPtr (withForeignPtr)+import System.Exit (exitSuccess)++import Graphics.Rendering.OpenGL.Raw.Core21+import Graphics.Rendering.OpenGL.Raw.ARB.ShaderObjects (glUniformMatrix4fvARB)+import Graphics.Rendering.OpenGL.Raw.ARB.FramebufferObjectCore (glGenerateMipmap)+import Graphics.Rendering.OpenGL.Capture (capturePPM)+import Graphics.UI.GLUT (getArgsAndInitialize, createWindow, displayCallback, ($=), swapBuffers, reportErrors, mainLoop)+import qualified Data.ByteString as BS+import Data.Array.Repa.IO.DevIL (runIL, readImage, Image(RGBA))+import Data.Array.Repa.Repr.ForeignPtr (toForeignPtr)++import Paths_butterflies (getDataFileName)++import Geometry.Flat.TwoD.Space+import Geometry.Flat.TwoD.Tessellation.Triangular++swarm' p q = tessellate p q 3 (Point (-12) (-12)) (Point 12 12)++class GLPoke t where glPoke :: t -> Ptr t -> IO (Ptr t)+instance GLPoke t => GLPoke [t] where+  glPoke [] p = return p+  glPoke (x:xs) p = glPoke x (castPtr p) >>= glPoke xs . castPtr++instance GLPoke GLfloat where glPoke x p = poke p x >> return (advancePtr p 1)+instance GLPoke Double where+  glPoke x p = do+    p <- glPoke (realToFrac x :: GLfloat) (castPtr p)+    return (castPtr p)+instance GLPoke Point where+  glPoke (Point x y) p = do+    p <- glPoke x (castPtr p)+    p <- glPoke y p+    return (castPtr p)+instance GLPoke Vertex where+  glPoke (Vertex vp vt h0 h1 h2) p = do+    p <- glPoke [vp, vt] (castPtr p)+    p <- glPoke [h0, h1, h2] (castPtr p)+    return (castPtr p)+instance GLPoke a => GLPoke (Triangle a) where+  glPoke (Triangle a b c) p = do+    p <- glPoke [a,b,c] (castPtr p)+    return (castPtr p)++vert = unlines+  [ "#version 120"+  , "uniform mat4 mvp;"+  , "attribute vec2 p0;"+  , "attribute vec2 t0;"+  , "attribute vec3 c0;"+  , "varying vec2 t;"+  , "varying vec3 c;"+  , "void main() {"+  , "  gl_Position = vec4(vec2(vec4(p0, 0.0, 1.0) * mvp), 0.0, 1.0);"+  , "  t = t0;"+  , "  c = c0;"+  , "}"+  ]++frag = unlines+  [ "#version 120"+  , "uniform sampler2D tex;"+  , "uniform sampler1D pal;"+  , "varying vec2 t;"+  , "varying vec3 c;"+  , "const float phi1 = (sqrt(5.0) - 1.0) / 2.0;"+  , "const float phi2 = (sqrt(5.0) - 2.0) / 2.0;"+  , "vec4 colour(float i) {"+  , "  float j = 1.0/6.0 - phi1 * i;"+  , "  float k = phi2 * i;"+  , "  j -= floor(j);"+  , "  k -= floor(k);"+  , "  k *= -0.5;"+  , "  k +=  1.0;"+  , "  return vec4(texture1D(pal, j).rgb * k, 1.0);"+  , "}"+  , "void main() {"+  , "  vec4 w = texture2D(tex, t);"+  , "  vec4 f = vec4(0.0);"+  , "  if (w.a <= 0.5) {"+  , "    f = vec4(0.5, 0.5, 0.5, 1.0);"+  , "  } else if (w.r >= 0.5 && w.g >= 0.5 && w.b >= 0.5) {"+  , "    f = vec4(1.0, 1.0, 1.0, 1.0);"+  , "  } else if (w.r <= 0.5 && w.g <= 0.5 && w.b <= 0.5) {"+  , "    f = vec4(0.0, 0.0, 0.0, 1.0);"+  , "  } else {"+  , "    float k = 0.0;"+  , "    if (w.r >= 0.5) {"+  , "      k = c.r;"+  , "    } else if (w.g >= 0.5) {"+  , "      k = c.g;"+  , "    } else if (w.b >= 0.5) {"+  , "      k = c.b;"+  , "    }"+  , "    f = colour(k);"+  , "  }"+  , "  gl_FragColor = f;"+  , "}"+  ]++main = do+  (_, [sp, sq]) <- getArgsAndInitialize+  _ <- createWindow "butterflies"+  program <- compileProgram+  glUseProgram program+  loadTextures+  let ip = read sp+      iq = read sq+      swarm = swarm' ip iq+      count = length swarm * 3+      stride = 4 * (2 + 2 + 3)+      bytes = count * fromIntegral stride+  allocaBytes bytes $ \p -> do+    glPoke swarm p+    vbo <- with 0 $ \q -> glGenBuffers 1 q >> peek q+    glBindBuffer gl_ARRAY_BUFFER vbo+    glBufferData gl_ARRAY_BUFFER (fromIntegral bytes) p gl_STATIC_DRAW+    att <- withCString "p0" $ glGetAttribLocation program+    glVertexAttribPointer (fromIntegral att) 2 gl_FLOAT (fromIntegral gl_FALSE) stride (plusPtr nullPtr 0)+    glEnableVertexAttribArray (fromIntegral att)+    att <- withCString "t0" $ glGetAttribLocation program+    glVertexAttribPointer (fromIntegral att) 2 gl_FLOAT (fromIntegral gl_FALSE) stride (plusPtr nullPtr (2 * 4))+    glEnableVertexAttribArray (fromIntegral att)+    att <- withCString "c0" $ glGetAttribLocation program+    glVertexAttribPointer (fromIntegral att) 3 gl_FLOAT (fromIntegral gl_FALSE) stride (plusPtr nullPtr (4 * 4))+    glEnableVertexAttribArray (fromIntegral att)+  let s = 10+      l = -s+      r = s+      t = -s+      b = s+      n = -1+      f = 1+      ortho = [ 2 / (r - l), 0, 0, -(r + l) / (r - l)+              , 0, 2 / (t - b), 0, -(t + b) / (t - b)+              , 0, 0, 2 / (f - n), -(f + n) / (f - n)+              , 0, 0, 0, 1 ]+  withArray ortho $ \p -> do+    loc <- withCString "mvp" $ glGetUniformLocation program+    glUniformMatrix4fvARB loc 1 (fromIntegral gl_FALSE) p+  loc <- withCString "tex" $ glGetUniformLocation program+  glUniform1i loc 0+  loc <- withCString "pal" $ glGetUniformLocation program+  glUniform1i loc 1+  glClearColor 0.5 0.5 0.5 1+  displayCallback $= do+    glClear gl_COLOR_BUFFER_BIT+    glDrawArrays gl_TRIANGLES 0 (fromIntegral count)+    swapBuffers+    let ipq = ip * ip + iq * iq + ip * iq+    capturePPM >>= BS.writeFile ("tessellation-" ++ (if ipq < 10 then "0" else "") ++ show ipq ++ "-" ++ show ip ++ "-" ++ show iq ++ ".ppm")+    reportErrors+    exitSuccess+  mainLoop++loadTextures = do+  RGBA img <- getDataFileName "butterfly.png" >>= runIL . readImage+  withForeignPtr (toForeignPtr img) $ \p -> do+    tex <- with 0 $ \q -> glGenTextures 1 q >> peek q+    glBindTexture gl_TEXTURE_2D tex+    glTexImage2D gl_TEXTURE_2D 0 (fromIntegral gl_RGBA) 1024 1024 0 gl_RGBA gl_UNSIGNED_BYTE p+    glTexParameteri gl_TEXTURE_2D gl_TEXTURE_MIN_FILTER (fromIntegral gl_LINEAR_MIPMAP_LINEAR)+    glTexParameteri gl_TEXTURE_2D gl_TEXTURE_MAG_FILTER (fromIntegral gl_LINEAR)+    glGenerateMipmap gl_TEXTURE_2D+  glActiveTexture gl_TEXTURE1+  RGBA img <- getDataFileName "palette.png" >>= runIL . readImage+  withForeignPtr (toForeignPtr img) $ \p -> do+    tex <- with 0 $ \q -> glGenTextures 1 q >> peek q+    glBindTexture gl_TEXTURE_1D tex+    glTexImage1D gl_TEXTURE_1D 0 (fromIntegral gl_RGBA) 256 0 gl_RGBA gl_UNSIGNED_BYTE p+    glTexParameteri gl_TEXTURE_1D gl_TEXTURE_MIN_FILTER (fromIntegral gl_NEAREST)+    glTexParameteri gl_TEXTURE_1D gl_TEXTURE_MAG_FILTER (fromIntegral gl_NEAREST)++compileProgram = do+  program <- glCreateProgram+  compileShader program gl_VERTEX_SHADER vert+  compileShader program gl_FRAGMENT_SHADER frag+  glLinkProgram program+  debugProgram program+  return program++compileShader program t src = do+  shader <- glCreateShader t+  withCString src $ \srcp -> with srcp $ \srcpp -> glShaderSource shader 1 srcpp nullPtr+  glCompileShader shader+  glAttachShader program shader+  debugShader shader+  glDeleteShader shader++debugProgram program = do+  if program /= 0+    then do+      linked <- with 0 $ \p -> glGetProgramiv program gl_LINK_STATUS p >> peek p+      when (linked /= fromIntegral gl_TRUE) $ putStrLn "link failed"+      len <- with 0 $ \p -> glGetProgramiv program gl_INFO_LOG_LENGTH p >> peek p+      when (len > 1) $ do+        allocaBytes (fromIntegral len + 1) $ \p -> glGetProgramInfoLog program len nullPtr p >> pokeByteOff p (fromIntegral len) (0 :: CUChar) >> peekCString p >>= putStrLn+    else putStrLn "no program"++debugShader shader = do+  if shader /= 0+    then do+      compiled <- with 0 $ \p -> glGetShaderiv shader gl_COMPILE_STATUS p >> peek p+      when (compiled /= fromIntegral gl_TRUE) $ putStrLn "compile failed"+      len <- with 0 $ \p -> glGetShaderiv shader gl_INFO_LOG_LENGTH p >> peek p+      when (len > 1) $ do+        allocaBytes (fromIntegral len + 1) $ \p -> glGetShaderInfoLog shader len nullPtr p >> pokeByteOff p (fromIntegral len) (0 :: CUChar) >> peekCString p >>= putStrLn+    else putStrLn "no shader"