68 lines
1.7 KiB
Haskell
68 lines
1.7 KiB
Haskell
{-# LANGUAGE TypeFamilies #-}
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module VertexBuffer where
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import qualified Graphics.Rendering.OpenGL as GL
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import SDL (($=), get)
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import Foreign
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-- internal imports
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import BindableClass
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import BufferClass
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-- layout of the VertexBuffer data object
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data VertexBuffer a = VertexBuffer
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{ vBufId :: GL.BufferObject -- buffer id
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, vBufSize :: GL.GLsizeiptr -- size of data
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, vBufData :: Ptr a -- pointer to data
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}
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-- instanciate typeclass from BufferClass and fill in missing implementations
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instance Buffer (VertexBuffer a) where
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type ObjName (VertexBuffer a) = GL.BufferObject
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target _ = GL.ArrayBuffer
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glId = vBufId
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initialize buf = do
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-- bind the buffer using the default iplementation of the typeclass
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bind buf
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-- fill in the data
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GL.bufferData (target buf) $=
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( vBufSize buf
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, vBufData buf
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, GL.StaticDraw
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)
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-- release the buffer using the default implementation of the typeclass
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unbind buf
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instance Bindable (VertexBuffer a) where
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-- bind the buffer
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bind buf = GL.bindBuffer (target buf) $= Just (glId buf)
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-- unbind the buffer
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unbind buf = GL.bindBuffer (target buf) $= Nothing
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newVertexBuffer ::
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(Storable a) => -- we have to be able to get a pointer to provided data
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[a] -> -- list of data elements
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IO (VertexBuffer a) -- newly built VertexBuffer data object
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newVertexBuffer list = do
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-- create the buffer object in applicative style
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buf <- VertexBuffer
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-- generate the ID
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<$> GL.genObjectName
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-- compute buffer size
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<*> pure (fromIntegral $ length list * sizeOf (head list))
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-- make pointer out of list
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<*> newArray list
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-- fill the data in to the buffer
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initialize buf
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-- return the data object
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return buf
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