Inline the two inner functions of the zoom traversal.

[spline3.git] / src / Grid.hs

diff --git a/src/Grid.hs b/src/Grid.hs
index 1a01ab7eb60bba873e31e087b645eaf8d83a3689..b8f1d759e1f268a1e71c33cfa5b7dd3dcb58919a 100644 (file)
--- a/src/Grid.hs
+++ b/src/Grid.hs
@@ -11,8 +11,9 @@ import FunctionValues
 import Misc (flatten)
 import Point (Point)
 import Tetrahedron (polynomial)
-import ThreeDimensional (contains_point)
-import Values (Values3D, dims, empty3d)
+import Values (Values3D, dims, empty3d, zoom_shape)
+
+import qualified Data.Array.Repa as R
 
 -- | 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
@@ -71,38 +72,64 @@ cube_at g i j k
     | 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
+
+--   The first cube along any axis covers (-h/2, h/2). The second
+--   covers (h/2, 3h/2).  The third, (3h/2, 5h/2), and so on.
+--
+--   We translate the (x,y,z) coordinates forward by 'h' so that the
+--   first covers (0, h), the second covers (h, 2h), etc. This makes
+--   it easy to figure out which cube contains the given point.
+calculate_containing_cube_coordinate :: Grid -> Double -> Int
+calculate_containing_cube_coordinate g coord
+    -- Don't use a cube on the boundary if we can help it.
+    | coord == delta && (xsize > 0 && ysize > 0 && zsize > 0) = 1
+    | otherwise = (ceiling ( (coord + delta) / cube_width )) - 1
     where
-      all_cubes = flatten $ cubes g
-      contains_our_point = flip contains_point p
+      (xsize, ysize, zsize) = dims (function_values g)
+      delta = (h g)
+      cube_width = 2 * delta
+
+
+-- | Takes a 'Grid', and returns a 'Cube' containing the given 'Point'.
+--   Since our grid is rectangular, we can figure this out without having
+--   to check every cube.
+find_containing_cube :: Grid -> Point -> Cube
+find_containing_cube g p =
+    case cube_at g i j k of
+      Just c -> c
+      Nothing -> error "No cube contains the given point."
+    where
+      (x, y, z) = p
+      i = calculate_containing_cube_coordinate g x
+      j = calculate_containing_cube_coordinate g y
+      k = calculate_containing_cube_coordinate g z
 
 
+{-# INLINE zoom_lookup #-}
+zoom_lookup :: Grid -> a -> (R.DIM3 -> Double)
+zoom_lookup g _ = zoom_result g
 
-zoom :: Grid -> Int -> [[[Double]]]
-zoom g scale_factor
-    | xsize == 0 || ysize == 0 || zsize == 0 = []
-    | otherwise =
-        [[[f p | i <- [0..scaled_zsize],
-                 let i' = scale_dimension i,
-                 let j' = scale_dimension j,
-                 let k' = scale_dimension k,
-                 let p = (i', j', k') :: Point,
-                 let c = (find_containing_cubes g p) !! 0,
-                 let t = (find_containing_tetrahedra c p) !! 0,
-                 let f = polynomial t]
-                 | j <- [0..scaled_ysize]]
-                   | k <- [0..scaled_xsize]]
+
+{-# INLINE zoom_result #-}
+zoom_result :: Grid -> R.DIM3 -> Double
+zoom_result g (R.Z R.:. i R.:. j R.:. k) =
+  f p
   where
-    scale_dimension :: Int -> Double
-    scale_dimension x = (fromIntegral x) / (fromIntegral scale_factor)
+    i' = fromIntegral i
+    j' = fromIntegral j
+    k' = fromIntegral k
+    p  = (i', j', k') :: Point
+    c = find_containing_cube g p
+    t = head (find_containing_tetrahedra c p)
+    f = polynomial t
 
-    fvs = function_values g
-    (xsize, ysize, zsize) = dims fvs
-    scaled_xsize = xsize * scale_factor
-    scaled_ysize = ysize * scale_factor
-    scaled_zsize = zsize * scale_factor
 
+zoom :: Grid -> Int -> Values3D
+zoom g scale_factor
+    | xsize == 0 || ysize == 0 || zsize == 0 = empty3d
+    | otherwise =
+        R.force $ R.traverse arr transExtent (zoom_lookup g)
+          where
+            arr = function_values g
+            (xsize, ysize, zsize) = dims arr
+            transExtent = zoom_shape scale_factor