GPipe

This is the official wiki for the GPipe package.

Example

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

I will continue adding examples to this page, so check back every once in a while. If you have any questions, feel free to mail me.

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