GPipe

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This is a wiki stub for the GPipe package. If you have any questions, feel free to mail me.

Example

This is a simple GPipe example that animates a spinning box. Besides GPipe, it uses the Vec-Transform package for the transformation matrices.

module Main where

import Graphics.GPipe
import Data.Monoid
import Data.IORef
import qualified Data.Vec as Vec
import Data.Vec.Nat
import Data.Vec.LinAlg.Transform3D
import Graphics.UI.GLUT
    (mainLoop,
     postRedisplay,
     idleCallback,
     getArgsAndInitialize,
     ($=))

sidePosX = toGPUStream TriangleStrip $ map (flip (,) (1:.0:.0:.()))  [1:.0:.0:.(), 1:.1:.0:.(), 1:.0:.1:.(), 1:.1:.1:.()]
sideNegX = toGPUStream TriangleStrip $ map (flip (,) ((-1):.0:.0:.())) [0:.0:.1:.(), 0:.1:.1:.(), 0:.0:.0:.(), 0:.1:.0:.()]
sidePosY = toGPUStream TriangleStrip $ map (flip (,) (0:.1:.0:.()))  [0:.1:.1:.(), 1:.1:.1:.(), 0:.1:.0:.(), 1:.1:.0:.()]
sideNegY = toGPUStream TriangleStrip $ map (flip (,) (0:.(-1):.0:.())) [0:.0:.0:.(), 1:.0:.0:.(), 0:.0:.1:.(), 1:.0:.1:.()]
sidePosZ = toGPUStream TriangleStrip $ map (flip (,) (0:.0:.1:.()))  [1:.0:.1:.(), 1:.1:.1:.(), 0:.0:.1:.(), 0:.1:.1:.()]
sideNegZ = toGPUStream TriangleStrip $ map (flip (,) (0:.0:.(-1):.())) [0:.0:.0:.(), 0:.1:.0:.(), 1:.0:.0:.(), 1:.1:.0:.()]

cube = mconcat [sidePosX, sideNegX, sidePosY, sideNegY, sidePosZ, sideNegZ]

transformedCube a = fmap (transform a) cube
transform :: Float -> (Vec3 (Vertex Float), Vec3 (Vertex Float)) -> (Vec4 (Vertex Float), Vec3 (Vertex Float))
transform a (pos, norm) = (transformedPos, transformedNorm)
    where
        modelMat = rotationVec (normalize (1:.0.5:.0.3:.())) a `multmm` translation (-0.5)
        viewMat = translation (-(0:.0:.2:.())) 
        projMat = perspective 1 100 (pi/3) (4/3)
        viewProjMat = projMat `multmm` viewMat
        transformedPos = toGPU (viewProjMat `multmm` modelMat) `multmv` homPoint pos
        transformedNorm = toGPU (Vec.map (Vec.take n3) $ Vec.take n3 $ modelMat) `multmv` norm

coloredFragments a = fmap (RGB . Vec.vec . dot (toGPU (0:.0:.1:.()))) $ rasterizeFront $ transformedCube a

paintSolid = paintColor NoBlending (RGB $ Vec.vec True)

main = do getArgsAndInitialize
          angleRef <- newIORef 0.0
          newWindow "Spinning box" (100:.100:.()) (800:.600:.())
                (do angle <- readIORef angleRef
                    writeIORef angleRef ((angle + 0.01) `mod'` (2*pi))
                    return $ paintSolid  (coloredFragments angle) (newFrameBufferColor (RGB 0))
                )
                (\ w -> idleCallback $= Just (postRedisplay (Just w)))
          mainLoop