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please help me debug my code

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jimjamjahaa

Joined: 03 Oct 2005
Posts: 17

Posted: Wed Oct 12, 2005 2:17 am Post subject: please help me debug my code

i am trying to implement some clipping in to my game

here are the 2 functions used for this

Code:

function compOutCode(x, y)
local outcode = 0
if y <0 then
   outcode = bottom
   end
if y > 272 then
   outcode = top
   end
if x < 0 then
   outcode = outcode + left
   end
if x > 480 then
   outcode = outcode + right
   end
return outcode
end

function drawLineClipped(x0,y0,x1,y1,col)
local accept, done = false
local out1, out2, outout, _x, _y = 0
out1 = compOutCode(x0, y0)
out2 = compOutCode(x1, y1)

repeat
   if (out1 == inside and out2 == indide) then
      accept = true
      done = true
      break
   elseif not out1 * out2 == inside then -- <<<HERE!
      done = true
      break
      end

   if out1 == inside then
      outout = out2
else
   outout = out1
   end

   -- if top in outout
   if outout == 2 or outout == 10 or outout == 11 then
      _x = x0 + (x1 - x0) * (272 - y0) / (y1 - y0)
      _y = ymax
      end
   -- if bottom
   if outout == 4 or outout == 12 or outout == 13 then
      _x = x0 + (x1 - x0) * (-y0) / (y1 - y0);
   _y = 272
   -- else if right
   elseif outout == 9 or outout == 13 or outout == 11 then
      _y = y0 + (y1 - y0) * (480 - x0) / (x1 - x0);
   _x = 480
   -- else if left
   elseif outout == 8 or outout == 12 or outout == 14 then
      _y = y0 + (y1 - y0) * (-x0) / (x1 - x0);
   _x = 0
   end

   if outout == out1 then
      x0 = _x
      y0 = _y
      out1 = compOutCode(x0,y0)
   else
      x1 = _x
      y1 = _y
      out2 = compOutCode(x1,y1)
      end
until done == true
if accept == true then
   screen:drawLine(x0,y0,x1,y1,col)
   end
end

i get an error at the place marked "-- <<<HERE!" complaining about doing arithmatic on a boolean variable. i mean, sure its declared as 0, but i dont mean for it to be boolean. the function compOutCode(x,y) will be returning 0 too in this scenario i am using it in.

so umm... help? please say if you dont get what im saying here.

arrggg

Joined: 29 Sep 2005
Posts: 11

Posted: Wed Oct 12, 2005 4:15 am Post subject:

is "bottom" and "top" defined?

jimjamjahaa

Joined: 03 Oct 2005
Posts: 17

Posted: Wed Oct 12, 2005 4:20 am Post subject:

Code:

-- globals
red = Color.new(255, 0, 0);
black = Color.new(0, 0, 0);
white = Color.new(255, 255, 255);
green = Color.new(0, 255, 0);
pi = 3.141592653589
rm_menu = 0
rm_game = 1
room = rm_game

inside = 0
top = 2
bottom = 4
left = 8
right = 9

is the first bit of code in the script :)

edit: its odd, when i get rid of the offending code, it complains about something in the function compOutCode(), but to get to where it has the original error, it must already have executed compOutCode twice.... strange.

i get the feeling it might be doing quite a few passes without an error, and then erroring at the end for some unforseen reason. i dont know. i need to know how to debug really, thus my other thread i posted ....

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