renderWire fb = let
  blend = Blend (FuncSubtract,FuncAdd) ((SrcColor,SrcColor),(SrcColor,OneMinusSrcAlpha)) (V4 0.0 1.0 0.0 0.0)
  modelViewProj = Uniform "viewProj" :: Mat 4 4 Float
  polyMode          = PolygonLine 20.0
  polyMode'        = PolygonPoint (PointSize 10.0)
  polyMode''         = PolygonFill
  rasterCtx         = TriangleCtx CullNone polyMode (Offset (-1) 0) FirstVertex
  fragmentCtx       = (DepthOp Lequal True,ColorOp NoBlending (V4 True True True True))
  vertexShader (v,n)    = (PrimMulMatVec modelViewProj (v3FToV4F v), v3FToV4F n)
  vertexStream      = fetch "missing shader" Triangle (Attribute "position" :: Vec 3 Float,Attribute "color" :: Vec 3 Float)
  primitiveStream   = mapPrimitives vertexShader vertexStream
  fragmentStream    = rasterizePrimitives rasterCtx Smooth primitiveStream
  fragmentShader = \f -> (V4 1.0 1.0 1.0 1.0)
 in accumulate fragmentCtx fragmentShader fragmentStream fb

render fb = let
  blend = Blend (FuncSubtract,FuncAdd) ((SrcColor,SrcColor),(SrcColor,OneMinusSrcAlpha)) (V4 0.0 1.0 0.0 0.0)
  modelViewProj = Uniform "viewProj" :: Mat 4 4 Float
  polyMode          = PolygonLine 20.0
  polyMode'        = PolygonPoint (PointSize 10.0)
  polyMode''         = PolygonFill
  rasterCtx         = TriangleCtx CullNone polyMode'' NoOffset FirstVertex
  fragmentCtx       = accumulationContext (DepthOp Less True,ColorOp NoBlending (V4 True True True True))
  vertexShader (v,n)    = (PrimMulMatVec modelViewProj (v3FToV4F v), v3FToV4F n)
  vertexStream      = fetch "missing shader" Triangle (Attribute "position" :: Vec 3 Float,Attribute "color" :: Vec 3 Float)
  primitiveStream   = mapPrimitives vertexShader vertexStream
  fragmentStream    = rasterizePrimitives rasterCtx Smooth primitiveStream
  fragmentShader = \f -> f-- (V4 1.0 1.0 1.0 0.2)
 in accumulate fragmentCtx fragmentShader fragmentStream fb

main = let
  emptyFB = FrameBuffer (DepthImage @1 1000,ColorImage @1 (V4 0.0 0.0 0.4 1.0))
 in ScreenOut $ renderWire $ render emptyFB