module MatrixHelper
    where
import Geometry

import Linear.Matrix
import Linear.V4
import Graphics.Rendering.OpenGL (GLfloat)

perspectiveMatrix :: Float -> Float -> Point2 -> Point2 -> Point2 -> [GLfloat]
perspectiveMatrix rot zoom (tranx,trany) (winx,winy) (viewFromx,viewFromy) =
    let scalMat = Linear.Matrix.transpose $
            V4 (V4 (2*zoom/winx) 0             0 (0::GLfloat))
                (V4 0             (2*zoom/winy) 0 0)
                (V4 0             0             1 0)
                (V4 0             0             0 1)
        rotMat = Linear.Matrix.transpose $
            V4 (V4 (cos rot) (sin (-rot)) 0 0)
                (V4 (sin rot) (cos rot)    0 0)
                (V4 0             0        1 0)
                (V4 0             0        0 1)
        tranMat3 = Linear.Matrix.transpose $
            V4 (V4 1        0        0 0)
                (V4 0        1        0 0)
                (V4 0        0        1 0)
                (V4 (-tranx) (-trany) 0 1)
        tranMat2 = Linear.Matrix.transpose $
            V4 (V4 1        0        0 0)
                (V4 0        1        0 0)
                (V4 0        0        1 0)
                (V4 (viewFromx-tranx) (viewFromy-trany) 0 1)
        perMat = Linear.Matrix.transpose $
             V4 (V4 1 0 0 0)
                (V4 0 1 0 0)
                (V4 0 0 1 1)
                (V4 0 0 0 1)
        tranMat1 = Linear.Matrix.transpose $
             V4 (V4 1        0        0 0)
                (V4 0        1        0 0)
                (V4 0        0        1 0)
                (V4 (-viewFromx) (-viewFromy) 0 1)
        wmat = scalMat !*! rotMat !*! tranMat2 !*! perMat !*! tranMat1
        vToL (V4 a b c d) = [a,b,c,d]
    in concatMap vToL $ vToL wmat