Pico-8 Hero - Breakout - Deflection Function Test

box_x = 32
box_y = 58
box_w = 64
box_h = 12

rayx = 0
rayy = 0
raydx = -2
raydy = -2

debug1 = "debug"

function _init()
end

function _update()
 if btn(1) then
  rayx+=1
 end
 if btn(0) then
  rayx-=1
 end
 if btn(2) then
  rayy-=1
 end
 if btn(3) then
  rayy+=1
 end
end

function _draw()
 cls()
 rect(box_x, box_y, box_x+box_w, box_y+box_h, 7)
 local px, py = rayx, rayy
 repeat
  pset(px, py, 8)
  px+=raydx
  py+=raydy
 until px<0 or px>128 or py < 0 or py > 128
 if deflx_ballbox(rayx,rayy,raydx,raydy,box_x,box_y,box_w,box_h) then
  print("horizontal")
 else
  print("vertical")
 end
 print(debug1)
end

function hit_ballbox(bx,by,tx,ty,tw,th)
 if bx+ball_r < tx then return false end
 if by+ball_r < ty then return false end
 if bx-ball_r > tx+tw then return false end
 if by-ball_r > ty+th then return false end
 return true
end

function deflx_ballbox(bx,by,bdx,bdy,tx,ty,tw,th)
 -- calculate wether to deflect the ball
 -- horizontally or vertically when it hits a box
 if bdx == 0 then
  -- moving vertically
  return false
 elseif bdy == 0 then
  -- moving horizontally
  return true
 else
  -- moving diagonally
  -- calculate slope
  local slp = bdy / bdx
  local cx, cy
  -- check variants
  if slp > 0 and bdx > 0 then
   -- moving down right
   debug1="q1"
   cx = tx-bx
   cy = ty-by
   if cx<=0 then
    return false
   elseif cy/cx < slp then
    return true
   else
    return false
   end
  elseif slp < 0 and bdx > 0 then
   debug1="q2"
   -- moving up right
   cx = tx-bx
   cy = ty+th-by
   if cx<=0 then
    return false
   elseif cy/cx < slp then
    return false
   else
    return true
   end
  elseif slp > 0 and bdx < 0 then
   debug1="q3"
   -- moving left up
   cx = tx+tw-bx
   cy = ty+th-by
   if cx>=0 then
    return false
   elseif cy/cx > slp then
    return false
   else
    return true
   end
  else
   -- moving left down
   debug1="q4"
   cx = tx+tw-bx
   cy = ty-by
   if cx>=0 then
    return false
   elseif cy/cx < slp then
    return false
   else
    return true
   end
  end
 end
 return false
end