Dome builder having strange issues,start position build off

local arg = { ... }
radius = tonumber(arg[1])
cslot = 1
function checkFuel()
  success = false
  while not success do
	if turtle.getFuelLevel() < 2 then
   turtle.select(16)
	  success = turtle.refuel(2)
   turtle.select(cslot)
else
   success = true
	end
	if not success then
		print("No fuel in slot 16.")
		print("Please add fuel and press enter to continue.")
		io.read()
	end
  end
end
-- Navigation features
-- allow the turtle to move while tracking its position
-- this allows us to just give a destination point and have it go there

positionx = radius
positiony = radius
facing = 0

function turnRightTrack()
  turtle.turnRight()
  facing = facing + 1
  if facing >= 4 then
	facing = 0
  end
end

function turnLeftTrack()
  turtle.turnLeft()
  facing = facing - 1
  if facing < 0 then
	facing = 3
  end
end
function safeForward()
  checkFuel()
  success = false
  while not success do
	success = turtle.forward()
	if not success then
	  print("Blocked attempting to move forward.")
	  print("Please clear and press enter to continue.")
	  io.read()
	end
  end
end
function safeBack()
  checkFuel()
  success = false
  while not success do
	success = turtle.back()
	if not success then
	  print("Blocked attempting to move back.")
	  print("Please clear and press enter to continue.")
	  io.read()
	end
  end
end
function safeUp()
  checkFuel()
  success = false
  while not success do
	success = turtle.up()
	if not success then
	  print("Blocked attempting to move up.")
	  print("Please clear and press enter to continue.")
	  io.read()
	end
  end
end

function safeDown()
  checkFuel()
  success = false
  while not success do
	success = turtle.down()
	if not success then
	  print("Blocked attempting to down up.")
	  print("Please clear and press enter to continue.")
	  io.read()
	end
  end
end

function moveToStart()
for i =1,radius do
  safeForward()
end

if radius <= 10 then
  downward = 3
else
  downward = 5
end
  for i = 1,downward do
   safeDown()
  end

--print("RDS")
--print(radius,downward)
--print("RDE")
end
function moveY(targety)
  if targety == positiony then
	return
  end

  if (facing ~= 0 and facing ~= 2) then -- check axis
	turnRightTrack()
  end

  while targety > positiony do
	if facing == 0 then
	  safeForward()
	else
	  safeBack()
	end
	positiony = positiony + 1
  end

  while targety < positiony do
	if facing == 2 then
	  safeForward()
	else
	  safeBack()
	end
	positiony = positiony - 1
  end
end

function moveX(targetx)
  if targetx == positionx then
	return
  end

  if (facing ~= 1 and facing ~= 3) then -- check axis
	turnRightTrack()
  end

  while targetx > positionx do
	if facing == 1 then
	  safeForward()
	else
	  safeBack()
	end
	positionx = positionx + 1
  end

  while targetx < positionx do
	if facing == 3 then
	  safeForward()
	else
	  safeBack()
	end
	positionx = positionx - 1
  end
end

function navigateTo(targetx, targety)
  -- Cost calculation mode - don't move
  if cost_only then
	return
  end
print(facing)
  if facing == 0 or facing == 2 then -- Y axis
	moveY(targety)
	moveX(targetx)
  else
	moveX(targetx)
	moveY(targety)
  end
end
function placeBlockLower()
  if turtle.getItemCount(cslot) == 0 then
	foundSlot = false
	while not foundSlot do
	  for i = 1,15 do
		if turtle.getItemCount(i) > 0 then
		  foundSlot = i
		  break
		end
	  end
	  if not foundSlot then
		-- No resources
		print("Out of building materials. Please refill and press enter to continue.")
		io.read()
	  end
	end
	cslot = foundSlot
	turtle.select(foundSlot)
  end

  turtle.placeDown()
end
function placeBlockUpper()
  if turtle.getItemCount(cslot) == 0 then
	foundSlot = false
	while not foundSlot do
	  for i = 5,15 do
		if turtle.getItemCount(i) > 0 then
		  foundSlot = i
		  break
		end
	  end
	  if not foundSlot then
		-- No resources
		print("Out of building materials. Please refill and press enter to continue.")
		io.read()
	  end
	end
	cslot = foundSlot
	turtle.select(foundSlot)
  end

  turtle.placeDown()
end
function buildLowerPart()
--Calculus

zstart = 0
zend = downward-1
radius = radius * 2
width = radius * 2 + 1
sqrt3 = 3 ^ 0.5
boundary_radius = radius + 1.0
boundary2 = boundary_radius ^ 2

--Calculus
for z = zstart,zend do
  if not cost_only then
	safeUp()
  end
  --print("Layer " .. z)
  cz2 = (radius - z) ^ 2

  limit_offset_y = (boundary2 - cz2) ^ 0.5
  max_offset_y = math.ceil(limit_offset_y)

  -- We do first the +x side, then the -x side to make movement efficient
  for side = 0,1 do
	-- On the right we go from small y to large y, on the left reversed
	-- This makes us travel clockwise around each layer
	if (side == 0) then
	  ystart = radius - max_offset_y
	  yend = radius + max_offset_y
	  ystep = 1
	else
	  ystart = radius + max_offset_y
	  yend = radius - max_offset_y
	  ystep = -1
	end
  
	for y = ystart,yend,ystep do
	  cy2 = (radius - y) ^ 2
	
	  remainder2 = (boundary2 - cz2 - cy2)
	
	
	  if remainder2 >= 0 then
		-- This is the maximum difference in x from the centre we can be without definitely being outside the radius

		max_offset_x = math.ceil((boundary2 - cz2 - cy2) ^ 0.5)
	  
		-- Only do either the +x or -x side
		if (side == 0) then
		  -- +x side
		  xstart = radius
		  xend = radius + max_offset_x
		else
		  -- -x side
		  xstart = radius - max_offset_x
		  xend = radius - 1
		end
	  
		-- Reverse direction we traverse xs when in -y side
		if y > radius then
		  temp = xstart
		  xstart = xend
		  xend = temp
		  xstep = -1
		else
		  xstep = 1
		end
	  
		for x = xstart,xend,xstep do
--[[
print("LS XS:" .. xstart,"-" .. x)
print("LP YS:" .. ystart,"-" .. y)
print("LP ZS:" .. zstart,"-" .. z)
--]]

		  cx2 = (radius - x) ^ 2
		  distance_to_centre = (cx2 + cy2 + cz2) ^ 0.5
		  -- Only blocks within the radius but still within 1 3d-diagonal block of the edge are eligible
  
	print(distance_to_centre)
	print(boundary_radius)
	print(sqrt3)
  
  
		  if distance_to_centre < boundary_radius and distance_to_centre + sqrt3 >= boundary_radius then
			offsets = {{0, 1, 0}, {0, -1, 0}, {1, 0, 0}, {-1, 0, 0}, {0, 0, 1}, {0, 0, -1}}
			for i=1,6 do
			  offset = offsets[i]
			  dx = offset[1]
			  dy = offset[2]
			  dz = offset[3]
			  if ((radius - (x + dx)) ^ 2 + (radius - (y + dy)) ^ 2 + (radius - (z + dz)) ^ 2) ^ 0.5 >= boundary_radius then
				-- This is a point to use
	--print("X:" .. x,"Y:" .. y)
				navigateTo(x, y)
				placeBlockLower()
				break
			  end
			end
			end
		  end
		end
	  end
	end
  end
--end
--print(radius,"-",radius)
radius = radius
navigateTo(radius,radius)

end
function buildRing(matID)
--Calculus
radius = radius
width = radius * 2 + 1
sqrt3 = 3 ^ 0.5
boundary_radius = radius + 1.0
boundary2 = boundary_radius ^ 2
zstart = radius
zend = zstart

--Calculus
for z = zstart,zend do
  if not cost_only then
	safeUp()
  end
  --print("Layer " .. z)
  cz2 = (radius - z) ^ 2

  limit_offset_y = (boundary2 - cz2) ^ 0.5
  max_offset_y = math.ceil(limit_offset_y)
	
  -- We do first the +x side, then the -x side to make movement efficient
  for side = 0,1 do
	-- On the right we go from small y to large y, on the left reversed
	-- This makes us travel clockwise around each layer
	if (side == 0) then
	  ystart = radius - max_offset_y
	  yend = radius + max_offset_y
	  ystep = 1
	else
	  ystart = radius + max_offset_y
	  yend = radius - max_offset_y
	  ystep = -1
	end
  
   --print("UP YS:" .. ystart)
  
	for y = ystart,yend,ystep do
	  cy2 = (radius - y) ^ 2
	
	  remainder2 = (boundary2 - cz2 - cy2)
	
	
	  if remainder2 >= 0 then
		-- This is the maximum difference in x from the centre we can be without definitely being outside the radius
		max_offset_x = math.ceil((boundary2 - cz2 - cy2) ^ 0.5)
	  
		-- Only do either the +x or -x side
		if (side == 0) then
		  -- +x side
		  xstart = radius
		  xend = radius + max_offset_x
		else
		  -- -x side
		  xstart = radius - max_offset_x
		  xend = radius - 1
		end
	  
		-- Reverse direction we traverse xs when in -y side
		if y > radius then
		  temp = xstart
		  xstart = xend
		  xend = temp
		  xstep = -1
		else
		  xstep = 1
		end
	  
		for x = xstart,xend,xstep do
		  cx2 = (radius - x) ^ 2
		  distance_to_centre = (cx2 + cy2 + cz2) ^ 0.5
		  -- Only blocks within the radius but still within 1 3d-diagonal block of the edge are eligible
		  if distance_to_centre < boundary_radius and distance_to_centre + sqrt3 >= boundary_radius then
			offsets = {{0, 1, 0}, {0, -1, 0}, {1, 0, 0}, {-1, 0, 0}, {0, 0, 1}, {0, 0, -1}}
			for i=1,6 do
			  offset = offsets[i]
			  dx = offset[1]
			  dy = offset[2]
			  dz = offset[3]
			  if ((radius - (x + dx)) ^ 2 + (radius - (y + dy)) ^ 2 + (radius - (z + dz)) ^ 2) ^ 0.5 >= boundary_radius then
				-- This is a point to use
				navigateTo(x, y)
	if matID >= 1 then
	 placeBlockUpper()
	else
	 placeBlockLower()
	end
  
				break
			  end
			end
		  end
		end
	  end
	end
  end
end
--print(radius,"-",radius)
navigateTo(radius,radius)
end

--Main Program run
cost_only = false
moveToStart()
r2 = radius
--print("R2:" .. r2)
buildLowerPart()
for i =1,3 do
buildRing(i)
end