Fractal Drawing - Coders

-- Fractal Drawing
-- by @beezing

imgHeight = 220
imgWidth  = 300

inCol  = 0   -- mandelbrot set color
colFac = 12  -- color gradient factor
maxIt  = 48  -- number of iterations

function Fractal(x0,y0, minRe,maxRe,minIm, jRe,jIm, R,G,B)
  maxIm = minIm+(maxRe-minRe)*(imgHeight/imgWidth)
  reFac = (maxRe-minRe)/imgWidth
  imFac = (maxIm-minIm)/imgHeight

  for y = 0, imgHeight-1 do
    cIm = maxIm - y*imFac
    for x = 0, imgWidth-1 do
      cRe = minRe + x*reFac
      zRe = cRe; zIm = cIm;

      n = 0; isIn = true; outCol = colFac;
      repeat
        n = n + 1
        zRe2 = zRe*zRe; zIm2 = zIm*zIm;
        zIm  = 2*zRe*zIm + (jIm or cIm)
        zRe  = zRe2-zIm2 + (jRe or cRe)
        isIn = not (zRe2+zIm2 > 4)

        if n < maxIt/2-1 then
          outCol = outCol + colFac
        else
          outCol = outCol - colFac
        end
      until (not isIn) or (n > maxIt-1)

      if isIn then
        setcolor(inCol,inCol,inCol)
      else
        if R then r = R-outCol else r = outCol end
        if G then g = G-outCol else g = outCol end
        if B then b = B-outCol else b = outCol end
        setcolor(r,g,b)
      end

      drawPoint(x+x0, y+y0)
    end
  end
end

clear()
--print('Calculating fractal image. Please wait...')
--disableScreenRefresh()
Fractal(10, 60,-1.1,-.6,-0.55,nil,nil,nil,nil,128)
Fractal(10,290,-1.7,1.7,-1.25,-.8,.15,128,nil,nil)
Fractal(10,520,-1.7,1.7,-1.25,-.7,.38,nil,128,nil)
--enableScreenRefresh()