Pass an optional offset to the viewport

1 files changed, 6 insertions, 5 deletions

diff --git a/src/Game/Map.hs b/src/Game/Map.hs
index 5da8133..8445a1b 100644
--- a/src/Game/Map.hs
+++ b/src/Game/Map.hs
@@ -13,7 +13,7 @@ module Game.Map
 where
 
 import Control.Monad
-import Data.Maybe (mapMaybe)
+import Data.Maybe (fromMaybe, mapMaybe)
 import qualified Game.Utils as U
 import SDL (($=))
 import qualified SDL
@@ -169,8 +169,9 @@ totalBatteries m = length $ filter isBattery (objects m)
 
 -- | Set the SDL viewport based on the map and the provided viewport coordinates.
 -- It returns the viewport to be used by render.
-viewport :: SDL.Renderer -> Map -> Int -> Int -> Int -> Int -> IO Viewport
-viewport renderer (Map mapData _) vx vy vw vh = do
+-- Optionally an offset can be provided.
+viewport :: SDL.Renderer -> Map -> Int -> Int -> Int -> Int -> Maybe (Int, Int) -> IO Viewport
+viewport renderer (Map mapData _) vx vy vw vh offs = do
   SDL.rendererViewport renderer $= Just mapRect
   pure $ Viewport newx newy vw vh
   where
@@ -187,8 +188,8 @@ viewport renderer (Map mapData _) vx vy vw vh = do
     newx = min (if fx + halfViewportWidth > mapWidth then mapWidth - vw else fx) (mapWidth - vw)
     newy = min (if fy + halfViewportHeight > mapHeight then mapHeight - vh else fy) (mapHeight - vh)
 
-    -- FIXME: hardcoded size of the HUD; perhaps we need to pass x, y offsets to the viewport
-    mapRect = U.rect (-newx) (16 - newy) (newx + vw) vh
+    (offsx, offsy) = fromMaybe (0, 0) offs
+    mapRect = U.rect (offsx - newx) (offsy - newy) (newx + vw) vh
 
 -- | Render a map.
 -- Requires a Viewport from viewport.