Add pairing.lua prototype

dominic/pairing.lua

@@ -0,0 +1,64 @@
+function pair(x, y)
+    return math.floor((x + y) * (x + y + 1)/2 + y)
+end
+
+function unpairX(z)
+    local j = math.floor(math.sqrt(0.25 + 2*z) - 0.5)
+    return j - (z - j*(j+1)/2)
+end
+
+
+function unpairZ(z)
+    local j = math.floor(math.sqrt(0.25 + 2*z) - 0.5)
+    return z - j * (j+1)/2;
+end
+
+lookup = {4, 1, 3, 0, 2}
+local function isDiggingSpot(x, y)
+    local val = lookup[(y % 5) + 1]
+    return (x % 5) == val
+end
+
+offset = 10
+function ithSpot(i)
+    j = offset
+    while true do
+        x, z = unpairX(j), unpairZ(j)
+        if isDiggingSpot(x, z) then
+            if i <= 1 then
+                return x, z
+            else
+                i = i - 1
+            end
+        end
+        j = j + 1
+    end
+end
+
+function digTo(x, z)
+    while z > 0 do
+        turtle.dig()
+        turtle.forward()
+        turtle.digUp()
+        z = z - 1
+    end
+    turtle.turnRight()
+    while x > 0 do
+        turtle.dig()
+        turtle.forward()
+        turtle.digUp()
+        x = x - 1
+    end
+
+function digSpot(i)
+    x, z = ithSpot(i)
+    digTo(x, z)
+    turtle.digDown()
+    turtle.down()
+end
+
+args = {...}
+spotnum = tonumber(args[1])
+if spotnum then
+    digSpot(spotNum)
+end