Mine: keep next shaft position

turtles/mine.lua

@@ -24,6 +24,10 @@ FUEL_LOW = 1000
 
 SHAFT_DEPTH = 100
 
+-- Start at this position to find the next shaft
+next_shaft_side = 0
+next_shaft_height = 0
+
 function distance_to_drop()
     return math.abs(depth - DROP_POINT_D)
     + math.abs(height - DROP_POINT_H)
@@ -178,42 +182,37 @@ function find_next_shaft()
         return is_shaft_pos() and turtle.detect()
     end
 
-    go_to(0, 0, 0)
+    go_to(next_shaft_height, 0, next_shaft_side)
 
     while true do
-        for hei=1,MAX_HEIGHT-1 do
+        if side % 2 == 0 then
+            while hei < MAX_HEIGHT - 1 do
+                if is_shaft() then
+                    return
+                end
+
+                if turtle.detectUp() then
+                    turtle.digUp()
+                end
+                move_up()
+            end
             if is_shaft() then
                 return
             end
+        else
+            while height > 0 do
+                if is_shaft() then
+                    return
+                end
 
-            if turtle.detectUp() then
-                turtle.digUp()
+                if turtle.detectDown() then
+                    turtle.digDown()
+                end
+                move_down()
             end
-            move_up()
-        end
-        if is_shaft() then
-            return
-        end
-
-        turn_abs(1)
-        if turtle.detect() then
-            turtle.dig()
-        end
-        move_forward()
-        turn_abs(0)
-
-        for hei=MAX_HEIGHT-1,1,-1 do
             if is_shaft() then
                 return
             end
-
-            if turtle.detectDown() then
-                turtle.digDown()
-            end
-            move_down()
-        end
-        if is_shaft() then
-            return
         end
 
         turn_abs(1)
@@ -242,6 +241,8 @@ function main()
     while true do
         print("Finding shaft")
         find_next_shaft()
+        next_shaft_height = height
+        next_shaft_side = side
         print("Mining shaft at position:")
         _dump_pos()
         mine_shaft()