shadowMapSize = 512

triangleCtx = TriangleCtx CullNone PolygonFill NoOffset LastVertex

gaussFilter7 :: [(Float, Float)]
gaussFilter7 = 
    [ (-3.0,   0.015625)
    , (-2.0,   0.09375)
    , (-1.0,   0.234375)
    , (0.0,    0.3125)
    , (1.0,    0.234375)
    , (2.0,    0.09375)
    , (3.0,    0.015625)
    ]

gaussFilter9 :: [(Float, Float)]
gaussFilter9 = 
    [ (-4.0,   0.05)
    , (-3.0,   0.09)
    , (-2.0,   0.12)
    , (-1.0,   0.15)
    , (0.0,    0.16)
    , (1.0,    0.15)
    , (2.0,    0.12)
    , (3.0,    0.09)
    , (4.0,    0.05)
    ]

blurCoefficients :: [(Float, Float)]
blurCoefficients = gaussFilter9

blur :: [(Float, Float)] -> Image 1 ('Color (Vec 4 Float)) -> FrameBuffer 1 '[ 'Color (Vec 4 Float) ]
blur coefficients img = filter1D dirH (PrjImage (filter1D dirV img))
  where
    dirH v = V2 (v / shadowMapSize) 0.0
    dirV v = V2 0.0 (v / shadowMapSize)

-- todo --    filter1D :: (Float -> Vec 2 Float) -> Image 1 ('Color (Vec 4 Float)) -> FrameBuffer 1 '[ 'Color (Vec 4 Float) ]
    filter1D dir img = accumulate accCtx frag
                                 (rasterizePrimitives triangleCtx ((NoPerspective)) prims) clearBuf
      where
        accCtx = ((ColorOp NoBlending (V4 True True True True)))
        clearBuf = FrameBuffer ((ColorImage @1 (V4 0 0 0 0.0)))
--        vert :: Vec 2 Float -> VertexOut (Vec 2 Float)
        vert ((uv)) = (pos, uv')
          where
            uv'    = uv *! 0.5 +! 0.5
            pos    = V4 uv%x uv%y 1.0 1.0

        prims = mapPrimitives vert (fetch "postSlot" ((Attribute "position")) :: PrimitiveStream Triangle ((Vec 2 Float)))

--        frag :: FragmentShader (Vec 2 Float -> Color (Vec 4 Float))
        frag ((uv)) = ((sample))
          where
            tex = Texture2D (V2 shadowMapSize shadowMapSize) img
            smp = Sampler LinearFilter ClampToEdge tex
            sample = foldr1 (\a b -> a + b) [ texture2D smp (uv + dir ofs) *! coeff
                                            | (ofs, coeff) <- coefficients
                                            ]

moments :: FrameBuffer 1 '[Depth Float, Color (Vec 4 Float)]
moments = accumulate accCtx frag (rasterizePrimitives triangleCtx ((Smooth)) prims) clearBuf
  where
    accCtx = (DepthOp Less True, ColorOp NoBlending (V4 True True True True))
    clearBuf = FrameBuffer (DepthImage @1 1000, ColorImage @1 (V4 0.0 0.0 0.0 1.0{-todo: use 1-}))

    lightMatrix = Uniform "lightMatrix" :: Mat 4 4 Float
    modelMatrix = Uniform "modelMatrix" :: Mat 4 4 Float

--    vert :: ((Vec 3 Float)) -> ((Float
    vert ((pos)) = (lightPos, depth)
      where
        lightPos = lightMatrix *. modelMatrix *. v3FToV4F pos
        depth = lightPos%z

    prims = mapPrimitives vert (fetch "geometrySlot" ((Attribute "position" :: Vec 3 Float)))

--    frag :: Float -> (Depth Float,Color (Vec 4 Float))
    frag ((depth)) = (depth, V4 moment1 moment2 0 1)
      where
        dx = dFdx depth
        dy = dFdy depth
        moment1 = depth
        moment2 = depth *! depth +! 0.25 *! (dx *! dx +! dy *! dy)
{-
depth :: FrameBuffer 1 (Depth Float, Color (Vec 4 Float))
depth = accumulate accCtx PassAll frag (Rasterize triangleCtx prims) clearBuf
  where
    accCtx = accumulationContext (DepthOp Less True, ColorOp NoBlending (V4 True True True True))
    clearBuf = FrameBuffer (DepthImage @1 1000, ColorImage @1 (V4 0.0 0.0 0.0 1.0))

    lightMatrix = Uniform "lightMatrix" :: Mat 4 4 Float
    modelMatrix = Uniform "modelMatrix" :: Mat 4 4 Float

    vert :: Vec 3 Float -> VertexOut Float
    vert pos = VertexOut lightPos 1 () (Smooth depth)
      where
        lightPos = lightMatrix *. modelMatrix *. v3FToV4F pos
        depth = lightPos%z

    prims = Transform vert (fetch "geometrySlot" Triangle (Attribute "position" :: Vec 3 Float))

    frag :: FragmentShader (Float -> (Depth Float, Color (Vec 4 Float)))
    frag = FragmentShaderRastDepth $ \depth -> (V4 depth 0 0 1)

vsm :: FrameBuffer 1 (Depth Float, Color (Vec 4 Float))
vsm = accumulate accCtx PassAll frag (Rasterize triangleCtx prims) clearBuf
  where
    accCtx = accumulationContext (DepthOp Less True, ColorOp NoBlending (V4 True True True True))
    cameraMatrix = Uniform "cameraMatrix" :: Mat 4 4 Float
    lightMatrix = Uniform "lightMatrix" :: Mat 4 4 Float
    modelMatrix = Uniform "modelMatrix" :: Mat 4 4 Float
    lightPosition = Uniform "lightPosition" :: Vec 3 Float

    shadowMap = Texture2D (V2 shadowMapSize shadowMapSize) (PrjImageColor moments)
    shadowMapBlur = Texture2D (V2 shadowMapSize shadowMapSize) (PrjImage blurredMoments)
      where
        blurredMoments = blur blurCoefficients (PrjImageColor moments)
    sampler = Sampler LinearFilter ClampToEdge shadowMapBlur

    frag :: FragmentShader ((Vec 3 Float, Vec 4 Float, Vec 3 Float) -> (Depth Float, Color (Vec 4 Float)))
    frag = FragmentShaderRastDepth $ \(worldPos, lightPos, worldNormal) -> (luminance)
      where
        clampUV x = clampS x 0.0 1.0
        scaleUV x = x *! 0.5 +! 0.5
        lightU = lightPos%x
        lightV = lightPos%y
        lightDepth = lightPos%z
        lightW = lightPos%w
        uv = clampUV (scaleUV ((V2 lightU lightV) /! lightW))
        
        val = texture2D sampler uv
        moment1 = val%x
        moment2 = val%y
        variance = max 0.002 (moment2 -! moment1 *! moment1)
        distance = max 0.0 (lightDepth -! moment1)
        lightProbMax = variance /! (variance +! distance *! distance)
        
        lambert = max 0.0 (dot worldNormal (normalize (lightPosition - worldPos)))
        
        uv' = uv -! 0.5
        spotShape = 1.0 -! length uv *! 4.0
        intensity = max 0 (spotShape *! lambert)
        
        val2 = scaleUV (round (uv' *! 10.0)) *! intensity
        spotR = val2%x
        spotG = val2%y
        
        luminance = (V4 spotR spotG intensity 1.0) *! pow lightProbMax 2.0
        

    clearBuf = FrameBuffer ( DepthImage @1 1000
                           , ColorImage @1 (V4 0.1 0.2 0.6 1))

    vert :: (Vec 3 Float, Vec 3 Float) -> VertexOut (Vec 3 Float, Vec 4 Float, Vec 3 Float)
    vert (localPos, localNormal) = VertexOut viewPos 1 () (Smooth worldPos%xyz, ((Smooth)) lightPos, ((Smooth)) worldNormal)
      where
        worldPos = modelMatrix *. v3FToV4F localPos
        viewPos = cameraMatrix *. worldPos
        lightPos = lightMatrix *. worldPos
        worldNormal = normalize ((modelMatrix *. v3FToV4F localNormal)%xyz)

    prims = Transform vert (fetch "geometrySlot" Triangle (Attribute "position" :: Vec 3 Float, Attribute "normal" :: Vec 3 Float))


sm :: FrameBuffer 1 (Depth Float, Color (Vec 4 Float))
sm = accumulate accCtx PassAll frag (Rasterize triangleCtx prims) clearBuf
  where
    accCtx = accumulationContext (DepthOp Less True, ColorOp NoBlending (V4 True True True True))
    clearBuf = FrameBuffer (DepthImage @1 1000, ColorImage @1 (V4 0.1 0.2 0.6 1))
    cameraMatrix = Uniform "cameraMatrix" :: Mat 4 4 Float
    lightMatrix = Uniform "lightMatrix" :: Mat 4 4 Float
    modelMatrix = Uniform "modelMatrix" :: Mat 4 4 Float
    lightPosition = Uniform "lightPosition" :: Vec 3 Float

    vert :: (Vec 3 Float, Vec 3 Float) -> VertexOut (Vec 3 Float, Vec 4 Float, Vec 3 Float)
    vert (localPos, localNormal) = VertexOut viewPos 1 () (Smooth (worldPos%xyz), ((Smooth)) lightPos, ((Smooth)) worldNormal)
      where
        worldPos = modelMatrix *. v3FToV4F localPos
        viewPos = cameraMatrix *. worldPos
        lightPos = lightMatrix *. worldPos
        worldNormal = normalize ((modelMatrix *. v3FToV4F localNormal)%xyz)

    prims = Transform vert (fetch "geometrySlot" Triangle (Attribute "position" :: Vec 3 Float, Attribute "normal" :: Vec 3 Float))

    --shadowMap :: Exp Obj (Texture Tex2D SingleTex (Regular Float) Red)
    shadowMap = Texture2D (V2 shadowMapSize shadowMapSize) (PrjImageColor depth)
    sampler = Sampler PointFilter ClampToEdge shadowMap
    
    frag :: FragmentShader ((Vec 3 Float, Vec 4 Float, Vec 3 Float) -> (Depth Float, Color (Vec 4 Float)))
    frag = FragmentShaderRastDepth $ \(worldPos, lightPos, worldNormal) -> (luminance)
      where
        lightU = lightPos%x
        lightV = lightPos%y
        lightDepth = lightPos%z
        lightW = lightPos%w
        clampUV x = clampS x 0 1
        scaleUV x = x *! 0.5 +! 0.5
        uv = clampUV (scaleUV ((V2 lightU lightV) /! lightW))
        
        surfaceDistance = (texture2D sampler uv)%x
        lightPortion = if (lightDepth <= surfaceDistance +! 0.01) then 1 else 0
        
        lambert = max 0 (dot worldNormal (normalize (lightPosition - worldPos)))
        
        --intensity = lambert @* lightPortion
        --luminance = pack' (V4 intensity intensity intensity (floatF 1))
        
        uv' = uv -! 0.5
        spotShape = 1 -! length uv' *! 4
        intensity = max 0 (spotShape *! lambert)

        val = scaleUV (round (uv' *! 10)) *! intensity
        spotR = val%x
        spotG = val%y
        
        luminance = (V4 spotR spotG intensity 1) *! lightPortion
        
main = ScreenOut sm
-}