X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FGrid.hs;h=efa63418947c308e7bed8c25619dadbc8d9d0a8e;hb=f6d0c289ad3397cf392976c24f3afdb17da5d377;hp=6d360e2c103d61cc6b41a9cc3873f52db756e169;hpb=6fb9ab6b6068870323e996da931fc04c7710e3e4;p=spline3.git

diff --git a/src/Grid.hs b/src/Grid.hs
index 6d360e2..efa6341 100644
--- a/src/Grid.hs
+++ b/src/Grid.hs
@@ -4,8 +4,14 @@
 module Grid
 where
 
+import Test.QuickCheck (Arbitrary(..), Gen, Positive(..))
+
 import Cube (Cube(Cube))
 import FunctionValues
+import Misc (flatten)
+import Point (Point)
+import ThreeDimensional (contains_point)
+
 
 -- | Our problem is defined on a Grid. The grid size is given by the
 --   positive number h. The function values are the values of the
@@ -16,6 +22,13 @@ data Grid = Grid { h :: Double, -- MUST BE GREATER THAN ZERO!
           deriving (Eq, Show)
 
 
+instance Arbitrary Grid where
+    arbitrary = do
+      (Positive h') <- arbitrary :: Gen (Positive Double)
+      fvs <- arbitrary :: Gen [[[Double]]]
+      return (make_grid h' fvs)
+
+
 -- | The constructor that we want people to use. If we're passed a
 --   non-positive grid size, we throw an error.
 make_grid :: Double -> [[[Double]]] -> Grid
@@ -29,9 +42,8 @@ empty_grid :: Grid
 empty_grid = Grid 1 [[[]]]
 
 
-
--- This is how we do a 'for' loop in Haskell.
--- No, seriously.
+-- | Returns a three-dimensional list of cubes centered on the grid
+--   points of g with the appropriate 'FunctionValues'.
 cubes :: Grid -> [[[Cube]]]
 cubes g
     | fvs == [[[]]] = [[[]]]
@@ -43,5 +55,29 @@ cubes g
     where
       fvs = function_values g
       zsize = (length fvs) - 1
-      ysize = (length $ head fvs) - 1
-      xsize = (length $ head $ head fvs) - 1
+      ysize = length (head fvs) - 1
+      xsize = length (head $ head fvs) - 1
+
+
+-- | Takes a grid and a position as an argument and returns the cube
+--   centered on that position. If there is no cube there (i.e. the
+--   position is outside of the grid), it will return 'Nothing'.
+cube_at :: Grid -> Int -> Int -> Int -> Maybe Cube
+cube_at g i j k
+    | i < 0 = Nothing
+    | j < 0 = Nothing
+    | k < 0 = Nothing
+    | i >= length (cubes g) = Nothing
+    | j >= length ((cubes g) !! i) = Nothing
+    | k >= length (((cubes g) !! i) !! j) = Nothing
+    | otherwise = Just $ (((cubes g) !! i) !! j) !! k
+
+
+-- | Takes a 'Grid', and returns all 'Cube's belonging to it that
+--   contain the given 'Point'.
+find_containing_cubes :: Grid -> Point -> [Cube]
+find_containing_cubes g p =
+    filter contains_our_point all_cubes
+    where
+      all_cubes = flatten $ cubes g
+      contains_our_point = flip contains_point p