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只是为了弄乱 Haskell 的 Gloss 库，我写道：

import Graphics.Gloss

data World = World { worldBugs :: [Picture] }

bug :: Point -> Float -> Picture
bug (x, y) s =
    let head = Translate x (y - s) $ Circle (s * 0.8)
        body = Translate x (y + s) $ Circle (s * 1.2)
    in  pictures [head, body]

main = play (InWindow "Animation Test" (400, 400) (100, 100)) white 10
    (World . map (\(n,b) -> Translate (n * 20) (n * 20) $ b) $ zip [0..] $ replicate 100 $ bug (0,0) 100)
    (\world -> pictures $ worldBugs world)
    (\event world -> world)
    (\time (World bs) -> World $ map (Rotate (time * 10)) bs)

它显示了随着时间的推移旋转的一些“错误”（形成头部和躯干的两个圆圈）。问题是，运行几秒钟后，它崩溃了：

Gloss / OpenGL Stack Overflow "after drawPicture."
  This program uses the Gloss vector graphics library, which tried to
  draw a picture using more nested transforms (Translate/Rotate/Scale)
  than your OpenGL implementation supports. The OpenGL spec requires
  all implementations to have a transform stack depth of at least 32,
  and Gloss tries not to push the stack when it doesn't have to, but
  that still wasn't enough.

  You should complain to your harware vendor that they don't provide
  a better way to handle this situation at the OpenGL API level.

  To make this program work you'll need to reduce the number of nested
  transforms used when defining the Picture given to Gloss. Sorry.

如果我理解正确，这基本上意味着最终，太多的转换被放入堆栈，并且它溢出。它指出这可能是硬件限制（我使用的是 Surface 2 Pro），那么我是 SOL 吗？使用时不这样做animate，但这可能是因为它没有在每个刻度上传递一个状态。

如果我要制作游戏，我将不得不使用play将状态传递给下一个滴答；我不能把所有事情都按时。有没有解决的办法？谷歌搜索错误几乎没有结果。

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1 回答 1

1

问题在于，在每个“滴答”上，它通过将图片包装在另一个转换中来进一步嵌套图片（最终导致溢出）。为了解决这个问题，我只是将每个值存储在一个Entity对象中，然后在fromEntity.

    {- LANGUAGE threaded -}
module GlossTest where

import Graphics.Gloss

data Entity = Entity { entRot :: Float, entTrans :: Point, entScale :: Point, entPict :: Picture }

data World = World { worldBugs :: [Entity] }

entTranslate :: Float -> Float -> Entity -> Entity
entTranslate x y (Entity r t s p) = Entity r (x,y) s p

entRotate :: Float -> Entity -> Entity
entRotate x (Entity r t s p) = Entity x t s p

entRotateBy :: Float -> Entity -> Entity
entRotateBy n (Entity r t s p) = Entity (r + n) t s p

entMove :: Float -> Float -> Entity -> Entity
entMove x y (Entity r (tX,tY) s p) = Entity r (tX + x, tY + y) s p

toEntity :: Picture -> Entity
toEntity = Entity 0 (0,0) 1

fromEntity :: Entity -> Picture
fromEntity (Entity r (tX,tY) (sX,sY) p) = Rotate r . Translate tX tY $ Scale sX sY p

bug :: Point -> Float -> Entity
bug (x, y) s =
    let head = Rotate 0 $ Translate x (y - s) $ Circle (s * 0.8)
        body = Rotate 0 $ Translate x (y + s) $ Circle (s * 1.2)
    in  toEntity $ pictures [head, body]

main = play
    (InWindow "Animation Test" (400, 400) (100, 100)) white 1
    (World . map (\(n,b) -> entTranslate (n * 1) (n * 1) $ b) $ zip [0..] $ replicate 10 $ bug (0,0) 100)
    (\world -> pictures . map fromEntity $ worldBugs world)
    (\event world -> world)
    (\time (World bs) -> World $ map (\(n,b) -> entRotateBy (n * time) $ entMove time time b) $ zip [0..] bs)
于 2014-10-28T03:08:00.433 回答