Add support for clamping pictures to be inside screen

src/Dodge/Base/Window.hs

@@ -5,6 +5,7 @@ import Dodge.Data
 import Dodge.Config.Data
 import Geometry
 
+-- | A box covering the screen in world coordinates
 screenPolygon :: World -> [Point2]
 screenPolygon w = [tr,tl,bl,br]
   where 
@@ -17,9 +18,36 @@ screenPolygon w = [tr,tl,bl,br]
     br = scTran $ scRot $ scZoom (V2 ( halfWidth w) (-halfHeight w))
     bl = scTran $ scRot $ scZoom (V2 (-halfWidth w) (-halfHeight w))
 
+-- | A box covering the screen in world coordinates, with a x and y border
+screenPolygonBord 
+    :: Float    -- ^ X border
+    -> Float    -- ^ Y border
+    -> World
+    -> [Point2]
+screenPolygonBord xbord ybord w = [tr,tl,bl,br]
+  where 
+    hw = halfWidth  w - xbord
+    hh = halfHeight w - ybord
+    scZoom p | _cameraZoom w /= 0   = (1/_cameraZoom w) *.* p
+             | otherwise            = p
+    theTransform = (+.+ _cameraCenter w) . rotateV (_cameraRot w) . scZoom
+    tr = theTransform (V2   hw    hh ) 
+    tl = theTransform (V2 (-hw)   hh ) 
+    br = theTransform (V2   hw  (-hh))
+    bl = theTransform (V2 (-hw) (-hh))
+
 halfWidth,halfHeight :: World -> Float
 halfWidth w = getWindowX w / 2
 halfHeight w = getWindowY w / 2
 getWindowX ,getWindowY :: World -> Float 
 getWindowX = _windowX . _config
 getWindowY = _windowY . _config
+
+-- | A box of the size of the screen in screen centered coordinates
+screenBox 
+    :: World
+    -> [Point2]
+screenBox w = rectNSEW hh (-hh) hw (-hw)
+  where
+    hw = halfWidth w
+    hh = halfHeight w