from manim import *

field = Rectangle(width=10.0, height=5.0)

class Billboard(Rectangle):
    
    def __init__(self, x, y, w, h):
        Rectangle.__init__(self, width=w, height=h)
        self.x = x
        self.y = y
        self.w = w
        self.h = h
        self.align_to(field, UL)
        self.shift(x*RIGHT + y*DOWN)

class Scanline(VGroup):

    def __init__(self):
        self.line = Line(field.get_top(), field.get_bottom(), color=RED).align_to(field, LEFT)
        self.tops = dict()
        VGroup.__init__(self)
        self.add(self.line)

    def insert(self, y):
        self.tops[y] = Dot().move_to(self.line.get_top()).shift(y*DOWN)
        self.add(self.tops[y])

    def delete(self, y):
        self.remove(self.tops[y])
        del self.tops[y]


class Main(Scene):
    def construct(self):

        boards = [Billboard(x, y, w, h) for x, y, w, h in [(1, 1, 2.3, 3.5), (1.5, 2, 9, 2), (2, 1.5, 4, 3), (3.7, 2.1, 3, 1.4), (4.5, 0, 2.8, 4.2), (6.3, 1.1, 2.8, 3.6)]]
        self.add(*boards)

        poi = sorted([(b.x, 1, i) for i, b in enumerate(boards)] + [(b.x + b.w, -1, i) for i, b in enumerate(boards)])
        
        scan = Scanline()

        for x, left, i in poi:
            self.play(scan.animate.move_to(field.get_left() + x*RIGHT))
            if left == 1:
                scan.insert(boards[i].y)
            else:
                scan.delete(boards[i].y)

            self.wait(0.5)


        self.wait(2)