Safer GL

module GL where

import Graphics.GL

-- Newtype for Buffers
newtype Buffer = Buffer GLuint

-- A class for types which map to a glenum
class IsGLenum e where
    toGLenum :: e -> GLenum

-- All Glenums and their instances for IsGLenum
data ArrayBuffer = ArrayBuffer
data UniformBuffer = UniformBuffer

instance IsGLenum ArrayBuffer where
    toGLenum ArrayBuffer = GL_ARRAY_BUFFER

instance IsGLenum UniformBuffer where
    toGLenum UniformBuffer = GL_UNIFORM_BUFFER

--
-- Definition for bindBuffer, it takes either GL_ARRAY_BUFFER or
-- GL_UNIFORM_BUFFER
--

class IsGLenum t => BindBufferTarget t where
instance BindBufferTarget ArrayBuffer where
instance BindBufferTarget UniformBuffer where
bindBuffer :: BindBufferTarget t => t -> Buffer -> IO ()
bindBuffer target (Buffer buffer) = glBindBuffer (toGLenum target) buffer

--
-- Definition for bindBufferBase, it doesn't take GL_ARRAY_BUFFER but does
-- take GL_UNIFORM_BUFFER
--
class IsGLenum t => BindBufferBaseTarget t where
instance BindBufferBaseTarget UniformBuffer where
bindBufferBase :: BindBufferBaseTarget t => t -> GLuint -> Buffer -> IO ()
bindBufferBase target index (Buffer buffer) = glBindBufferBase (toGLenum target) index buffer


----------------------------------------------------------------------------------------------------
-- sometime in the future
----------------------------------------------------------------------------------------------------

data SuperNewBuffer = SuperNewBuffer

instance IsGLenum SuperNewBuffer where
    toGLenum SuperNewBuffer = GL_SUPER_NEW_BUFFER

instance BindBufferTarget SuperNewBuffer