Change chainsaw cutting algorithm back to old one

The new algorithm caused horizontal sections of trees to be left, with the
sections above and below them removed.

diff --git a/technic/tools/chainsaw.lua b/technic/tools/chainsaw.lua
index 36422d9ae9c9e93673f90224ee6487957eb07999..9e4bae0f0b5c0804baf92f22bc619ece417af6d1 100644 (file)
--- a/technic/tools/chainsaw.lua
+++ b/technic/tools/chainsaw.lua
@@ -148,36 +148,51 @@ local function handle_drops(drops)
 end
 
 --- Iterator over positions to try to saw around a sawed node.
--- This returns nodes in a 3x2x3 area. It does not return lower (y) positions
--- to prevent the chainsaw from cutting down nodes below the cutting position.
+-- This returns positions in a 3x1x3 area around the position, plus the
+-- position above it.  This does not return the bottom position to prevent
+-- the chainsaw from cutting down nodes below the cutting position.
 -- @param pos Sawing position.
 local function iterSawTries(pos)
        -- Copy position to prevent mangling it
        local pos = vector.new(pos)
-       -- Shift the position down on the x and z axes
-       pos.x, pos.z = pos.x - 1, pos.z - 1
-       -- Save our starting position for reseting it later
-       local startx, startz = pos.x, pos.z
-       -- We will move out by one in every direction except -y
-       local endx, endy, endz = pos.x + 2, pos.y + 1, pos.z + 2
-       -- Adjust for initial increment
-       pos.x = pos.x - 1
+       local i = 0
 
        return function()
-               if pos.x < endx then
+               i = i + 1
+               -- Given a (top view) area like so (where 5 is the starting position):
+               -- X -->
+               -- Z 123
+               -- | 456
+               -- V 789
+               -- This will return positions 1, 4, 7, 2, 8 (skip 5), 3, 6, 9,
+               -- and the position above 5.
+               if i == 1 then
+                       -- Move to starting position
+                       pos.x = pos.x - 1
+                       pos.z = pos.z - 1
+               elseif i == 4 or i == 7 then
+                       -- Move to next X and back to start of Z when we reach
+                       -- the end of a Z line.
                        pos.x = pos.x + 1
+                       pos.z = pos.z - 2
+               elseif i == 5 then
+                       -- Skip the middle position (we've already run on it)
+                       -- and double-increment the counter.
+                       pos.z = pos.z + 2
+                       i = i + 1
+               elseif i <= 9 then
+                       -- Go to next Z.
+                       pos.z = pos.z + 1
+               elseif i == 10 then
+                       -- Move back to center and up.
+                       -- The Y+ position must be last so that we don't dig
+                       -- straight upward and not come down (since the Y-
+                       -- position isn't checked).
+                       pos.x = pos.x - 1
+                       pos.z = pos.z - 1
+                       pos.y = pos.y + 1
                else
-                       pos.x = startx
-                       if pos.z < endz then
-                               pos.z = pos.z + 1
-                       else
-                               pos.z = startz
-                               if pos.y < endy then
-                                       pos.y = pos.y + 1
-                               else
-                                       return nil
-                               end
-                       end
+                       return nil
                end
                return pos
        end
@@ -195,7 +210,7 @@ local function recursive_dig(pos, remaining_charge)
                return remaining_charge
        end
 
-       -- wood found - cut it
+       -- Wood found - cut it
        handle_drops(minetest.get_node_drops(node.name, ""))
        minetest.remove_node(pos)
        remaining_charge = remaining_charge - chainsaw_charge_per_node