Only compute 'cubes' once, and store it in a new Grid field, cube_grid.

[spline3.git] / src / Grid.hs

diff --git a/src/Grid.hs b/src/Grid.hs
index 8bf83828e9f23a97de57360ffeded92ebb92ccd2..ba8ca2007621c9e31536788d8204e0d0e6306463 100644 (file)
--- a/src/Grid.hs
+++ b/src/Grid.hs
@@ -24,7 +24,8 @@ type CubeGrid = Array (Int,Int,Int) Cube
 --   function at the grid points, which are distance h from one
 --   another in each direction (x,y,z).
 data Grid = Grid { h :: Double, -- MUST BE GREATER THAN ZERO!
-                   function_values :: Values3D }
+                   function_values :: Values3D,
+                   cube_grid :: CubeGrid }
           deriving (Eq, Show)
 
 
@@ -40,31 +41,32 @@ instance Arbitrary Grid where
 make_grid :: Double -> Values3D -> Grid
 make_grid grid_size values
     | grid_size <= 0 = error "grid size must be positive"
-    | otherwise = Grid grid_size values
+    | otherwise = Grid grid_size values (cubes grid_size values)
 
 
 -- | Creates an empty grid with grid size 1.
 empty_grid :: Grid
-empty_grid = Grid 1 empty3d
+empty_grid = make_grid 1 empty3d
 
 
 -- | Returns a three-dimensional array of cubes centered on the grid
---   points of g with the appropriate 'FunctionValues'.
-cubes :: Grid -> CubeGrid
-cubes g
+--   points (h*i, h*j, h*k) with the appropriate 'FunctionValues'.
+cubes :: Double -> Values3D -> CubeGrid
+cubes delta fvs 
   = array (lbounds, ubounds)
            [ ((i,j,k), cube_ijk)
                  | i <- [0..xmax],
                    j <- [0..ymax],
                    k <- [0..zmax],
-                   let cube_ijk = Cube (h g) i j k (make_values fvs i j k)]
+                   let tet_vol = (1/24)*(delta^(3::Int)),
+                   let cube_ijk =
+                         Cube delta i j k (make_values fvs i j k) tet_vol]
      where
        xmax = xsize - 1
        ymax = ysize - 1
        zmax = zsize - 1
        lbounds = (0, 0, 0)
        ubounds = (xmax, ymax, zmax)
-       fvs = function_values g
        (xsize, ysize, zsize) = dims fvs
 
 
@@ -79,7 +81,7 @@ cube_at g i j k
     | j >= ysize = error "j >= ysize in cube_at"
     | k < 0      = error "k < 0 in cube_at"
     | k >= zsize = error "k >= zsize in cube_at"
-    | otherwise = (cubes g) ! (i,j,k)
+    | otherwise = (cube_grid g) ! (i,j,k)
       where
         fvs = function_values g
         (xsize, ysize, zsize) = dims fvs
@@ -95,7 +97,8 @@ calculate_containing_cube_coordinate g coord
     -- Don't use a cube on the boundary if we can help it. This
     -- returns cube #1 if we would have returned cube #0 and cube #1
     -- exists.
-    | coord == offset && (xsize > 0 && ysize > 0 && zsize > 0) = 1
+    | coord < offset = 0
+    | coord == offset && (xsize > 1 && ysize > 1 && zsize > 1) = 1
     | otherwise = (ceiling ( (coord + offset) / cube_width )) - 1
     where
       (xsize, ysize, zsize) = dims (function_values g)
@@ -126,9 +129,10 @@ zoom_result :: Grid -> ScaleFactor -> R.DIM3 -> Double
 zoom_result g (sfx, sfy, sfz) (R.Z R.:. i R.:. j R.:. k) =
   f p
   where
-    i' = (fromIntegral i) / (fromIntegral sfx)
-    j' = (fromIntegral j) / (fromIntegral sfy)
-    k' = (fromIntegral k) / (fromIntegral sfz)
+    offset = (h g)/2
+    i' = (fromIntegral i) / (fromIntegral sfx) - offset
+    j' = (fromIntegral j) / (fromIntegral sfy) - offset
+    k' = (fromIntegral k) / (fromIntegral sfz) - offset
     p  = (i', j', k') :: Point
     c = find_containing_cube g p
     t = find_containing_tetrahedron c p