require 'rubygems'
require 'inline'
require 'gl'
require 'glut'
 
class MandelSet
 
  # x,y -> topleft coordinate
  # x1,y1 -> bottomright coordinate
  # w -> width (pixel)
  # h -> height (pixel)
  def initialize(x,y,x1,y1,w,h)
    @x = x.to_f
    @y = y.to_f
    @rx = (x1 - x).to_f / w
    @ry = (y - y1).to_f / h
    @w = w
    @h = h
  end
 
  ## แปลงค่าพิกัดบน screen ไปเป็น พิกัดที่จะนำไปคำนวณ mandel set
  def from_screen(x,y)
    [@x + @rx * x, @y - @ry * y]
  end
 
  def zoom(x,y)
    [x - 100*@rx, y + 100*@ry, x + 100*@rx, y - 100*@ry, @w, @h]
  end
 
  inline do |builder|
    builder.c "
   VALUE mandel(double x, double y) {
    double x0 = x;
    double y0 = y;
    double x2 = x * x;
    double y2 = y * y;
    int cnt = 0;
    int max = 200;
    while (x2 + y2 < 4 && cnt < max) {
      y = 2*x*y + y0;
      x = x2 - y2 + x0;
 
      x2 = x*x;
      y2 = y*y;
 
      cnt++;
    }
    if (cnt == max || cnt == 0) {
      return rb_float_new(0.0);
    } else {
      return rb_float_new((double)cnt/(double)max);
    }
  }
"
  end
 
  def to_a
    ret = []
    (0..@w).each do |x|
      (0..@h).each do |y|
        c = mandel(*from_screen(x,y))
        ret << [x,y,c]        
      end
    end
    ret
  end
 
end

class MandelPlotter
  def initialize(x,y,x1,y1,w,h)
    @w = w
    @h = h
    @m = MandelSet.new(x,y,x1,y1,w,h)
    @result = @m.to_a
  end
 
  def run() 
    STDOUT.sync = TRUE
    Glut.glutInit
    Glut.glutInitWindowSize(@w, @h);
    a = Glut.glutCreateWindow("mandel set")
    Glut.glutDisplayFunc(disp)
    Glut.glutReshapeFunc(reshape);
    Glut.glutMouseFunc(mouseHandle);
    Glut.glutMainLoop;
  end
 
  def disp()
    Proc.new {
      Gl.glClear(Gl::GL_COLOR_BUFFER_BIT)
      Gl.glBegin(Gl::GL_POINTS)
      @result.each do |s|
        c = s[2]
        Gl.glColor(* chooseColor(c))    
        Gl.glVertex(s[0],s[1])
      end
      Gl.glEnd
      Gl.glFlush      
    }
  end
 
  def chooseColor(c) 
    if c > 0.1 && c < 0.3
	[c * 1.7 ,0,c * 1.2]
    elsif c > 0.3 && c < 0.5
        [0,c,0]
    elsif c > 0.5 && c < 0.7
        [0,0,c]
    elsif c > 0.7 && c < 0.9
	[0,c*0.3,c*1.1]
    else
    	[c,c,c]
    end
  end
 
  def reshape() 
    Proc.new {|w, h|
      Gl.glViewport(0, 0, w, h)
      Gl.glMatrixMode(Gl::GL_PROJECTION)
      Gl.glLoadIdentity
      Gl.glOrtho(0, w, 0, h, -1, 1)
      Gl.glScale(1, -1, 1)
      Gl.glTranslate(0, -h, 0)
    }
  end
 
  def mouseHandle()
    Proc.new do |b, state, x, y|
      if b == Glut::GLUT_LEFT_BUTTON && state == Glut::GLUT_UP
        nx,ny =  @m.from_screen(x,y)
        ret = @m.zoom(nx,ny)
        @m = MandelSet.new(*ret)
        @result = @m.to_a
        Glut.glutPostRedisplay
      end
    end
  end
end

p = MandelPlotter.new(ARGV[0].to_i,ARGV[1].to_i,ARGV[2].to_i,ARGV[3].to_i,400,400)
p.run