module Shader (drawShaderLay) where

import Control.Monad.Primitive
import qualified Data.Vector.Unboxed.Mutable as UMV
import Graphics.GL.Core45
import Shader.Data
import Shader.Parameters

drawShaderLay :: Int -> UMV.MVector (PrimState IO) Int -> Int -> (GLuint, VBO) -> IO ()
{-# INLINE drawShaderLay #-}
drawShaderLay l countsVector shadIn fs = do
    i <- UMV.read countsVector shadIn
    glUseProgram (fst fs)
    glUniform1i 0 . fromIntegral $ (l * numSubElements)
    glDrawArrays
        GL_TRIANGLES
        (fromIntegral $ l * numSubElements)
        (drawCountMod shadIn i)

drawCountMod :: Int -> Int -> GLsizei
drawCountMod i n
    | i == 3 = fromIntegral $ 2 * n  -- modifies ellipse draw count
    | otherwise = fromIntegral n