module Matrix(
    modelMatrixCube
  , modelMatrixWall
  , cameraMatrix
  , projMatrix
  , lightDirection
  , depthMVPCube
  , depthMVPWall
  ) where

import Linear
import qualified LambdaCube.Linear as LC 
import Game.GoreAndAsh.Math 

-- | Convert from linear matrix format to LambdaCube format
convLC :: M44 Float -> LC.M44F 
convLC (V4 !a !b !c !d) =  LC.V4 (cv a) (cv b) (cv c) (cv d)
  where
    cv (V4 !x !y !z !w) = LC.V4 x y z w

-- | Convert from linear vector format to LambdaCube format
convLCV :: V3 Float -> LC.V3F
convLCV (V3 !x !y !z) = LC.V3 x y z 

-- | Model matrix for rotating cube, maps from local model coords to world coords
modelMatrixCube :: Float -> LC.M44F 
modelMatrixCube = convLC . modelMatrixCube'

modelMatrixCube' :: Float -> M44 Float 
modelMatrixCube' t = quatMatrix $ axisAngle (normalize $ V3 1 1 3) t 

-- | Model matrix for static wall, maps from local model coords to world coords
modelMatrixWall :: LC.M44F 
modelMatrixWall = convLC modelMatrixWall'

modelMatrixWall' :: M44 Float 
modelMatrixWall' = scale (V3 1 7 7) !*! translate (V3 (-3) 0 0)

-- | Camera matrix, maps from world coords to camera coords
cameraMatrix :: Float -> LC.M44F 
cameraMatrix t = convLC $ lookAt eye (V3 0 0 0) (V3 0 1 0)
  where eye = rotate (axisAngle (V3 0 1 0) t) (V3 15 2 15)

-- | Projection matrix, maps from camera coords to device normalized coords
projMatrix :: Float -> LC.M44F 
projMatrix !aspect = convLC $ perspective (pi/3) aspect 0.1 100

-- | Direction of light
lightDirection :: LC.V3F
lightDirection = convLCV lightDir 

-- | Direction of light in Linear vector
lightDir :: V3 Float 
lightDir = normalize $ V3 (-3) 0.5 0 

-- | Matrix to view from directed light source
depthMVPCube :: Float -> LC.M44F 
depthMVPCube t = depthMVP $ modelMatrixCube' t

-- | Matrix to view from directed light source
depthMVPWall :: LC.M44F 
depthMVPWall = depthMVP modelMatrixWall'

depthMVP :: M44 Float -> LC.M44F 
depthMVP modelMtx = convLC . transpose $ proj !*! view !*! modelMtx
  where 
    view = lookAt (negate lightDir) (V3 0 0 0) (V3 0 1 0)
    proj = ortho (-10) 10 (-10) 10 (-10) (10)

-- | Transform quaternion to rotation matrix
quatMatrix :: Quaternion Float -> M44 Float 
quatMatrix q@(Quaternion !w (V3 !x !y !z)) = V4
  (V4 m00 m01 m02 0)
  (V4 m10 m11 m12 0) 
  (V4 m20 m21 m22 0) 
  (V4 0 0 0 1) 
  where
    s = 2 / norm q
    x2 = x * s
    y2 = y * s
    z2 = z * s
    xx = x * x2
    xy = x * y2
    xz = x * z2
    yy = y * y2
    yz = y * z2
    zz = z * z2
    wx = w * x2
    wy = w * y2
    wz = w * z2
    
    m00 = 1 - (yy + zz)
    m10 = xy - wz
    m20 = xz + wy
    
    m01 = xy + wz
    m11 = 1 - (xx + zz)
    m21 = yz - wx
    
    m02 = xz - wy
    m12 = yz + wx
    m22 = 1 - (xx + yy)