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let pi = 4. *. atan 1.
let deltay = 40_000. /. 360. /. 3600. *. 1000.
let deltax = deltay *. cos (44. *. pi /. 180.)
let precompute tile_height tile_width tile =
let normals =
Bigarray.(Array3.create Int8_signed C_layout) (tile_height - 2) (tile_width - 2) 3
in
let heights =
Bigarray.(Array2.create Float32 C_layout) (tile_height - 2) (tile_width - 2)
in
for y = 1 to tile_height - 2 do
for x = 1 to tile_width - 2 do
let nx = (tile.{y, x - 1} -. tile.{y, x + 1}) *. deltay in
let ny = (tile.{y - 1, x} -. tile.{y + 1, x}) *. deltax in
let nz = 2. *. deltax *. deltay in
let n = 127. /. sqrt ((nx *. nx) +. (ny *. ny) +. (nz *. nz)) in
normals.{tile_height - 2 - y, x - 1, 0} <- truncate (nx *. n);
normals.{tile_height - 2 - y, x - 1, 1} <- truncate (ny *. n);
normals.{tile_height - 2 - y, x - 1, 2} <- truncate (nz *. n);
heights.{tile_height - 2 - y, x - 1} <- tile.{y, x}
done
done
let tile_height = 1024
let tile_width = 1024
let tile = Bigarray.(Array2.create Float32 C_layout) tile_height tile_width
let () =
for _ = 1 to 30 do
precompute tile_height tile_width tile
done
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