{-# LANGUAGE TemplateHaskell #-}
{- |
Datatypes used to setup and pass data to shaders.
-}
module Shader.Data
    ( VAO (..)
    , VBO (..)
    , FullShader (..)
    , ShaderTexture (..)
    , EPrimitiveMode (..)
-- | Lens functions
    , vao
    , vaoVBO

    , shaderProgram
    , shaderVAO
    , shaderPokeStrategy
    , shaderDrawPrimitive
    , shaderTexture
    , shaderCustomUnis

--    , textureObject 
    ) where
import Picture.Data

import Graphics.Rendering.OpenGL
import Foreign
import Control.Lens
--import Graphics.GL.Types
{- | Vertex array object: contains the reference to the object,
and its buffer targets.  -}
data VAO = VAO
    { _vao :: VertexArrayObject
    , _vaoVBO :: VBO
    }
{- | Vertex buffer object: contains the reference to the object,
a pointer to a location with space that can be written to the buffer,
and a list of attribute pointer sizes.
Vertex attributes are interleaved within the vbo. -}
data VBO = VBO
    { _vbo      :: BufferObject
    , _vboPointer :: Ptr Float
    , _vboAttribSizes :: [Int]  -- ^ It is not clear to me if this is necessary to store or not
    }

{- | Datatype containing the necessary information for a single shader.  -}
data FullShader = FullShader
    { _shaderProgram :: Program
    , _shaderVAO :: VAO
    , _shaderPokeStrategy :: RenderType -> [[Float]]-- -> F.FoldM IO RenderType Int
    , _shaderDrawPrimitive :: EPrimitiveMode
    , _shaderTexture :: Maybe ShaderTexture
    , _shaderCustomUnis :: [UniformLocation]
    }
{- | Datatype containing the reference to a texture object.  -}
newtype ShaderTexture = ShaderTexture
    { _textureObject :: TextureObject }

data EPrimitiveMode
    = EPoints
    | ELines
    | ELinesAdjacency
    | ELineLoop
    | ELineStrip
    | ETriangles
    | ETriangleStrip
    | ETriangleFan
    | EQuads
    | EQuadStrip
    | EPolygon
    | EPatches

makeLenses ''VAO
makeLenses ''FullShader