Compounding Breakout

Announcements

• PS3 feedback coming later today
• I’m shooting for PS4 feedback by Wednesday
• Midterm on Friday!
  • First practice exam already out
  • Second practice exam to be posted later today
  • Learning objective checklist posted. Look it over as you study!
  • I’m not going to put timer events or complex shapes on the midterm since you have not completed an assignment with those ideas
    • Mouse events are fair game though
• Polling: rembold-class.ddns.net

Review Question

Which of the below blocks of code will create the image to the right? The window measures 500 x 200 pixels and the value of d is 150.

x, y = 250 - d / 2, 100 - d / 2
a1 = GArc(x, y, d, d, 90, -180)
gw.add(a1)

x, y = 250 - d, 100 - d
a1 = GArc(x, y, d, d, -180, 90)
gw.add(a1)

x, y = 250 - d / 2, 100 - d / 2
a1 = GArc(x, y, d, d, 90, 180)
gw.add(a1)

x, y = 250 - d / 2, 100 - d / 2
a1 = GArc(x, y, d, 180, -90)
gw.add(a1)

Triangle By Vertex

def triangle_by_vertex():
    def create_triangle(b, h):
        tri = GPolygon()
        tri.add_vertex(-b / 2, h / 2)
        tri.add_vertex(b / 2, h / 2)
        tri.add_vertex(0, -h / 2)
        return tri

    gw = GWindow(500, 500)
    triangle = create_triangle(200, 200)
    triangle.set_filled(True)
    triangle.set_color("red")
    gw.add(triangle, 250, 250)

Triangle by Polar Edge

def triangle_by_polar_edge():
    def create_eq_triangle(side):
        tri = GPolygon()
        tri.add_vertex(0, 0)
        for i in range(0, 360, 120):
            tri.add_polar_edge(side, i)
        return tri

    gw = GWindow(500, 500)
    triangle = create_eq_triangle(100)
    triangle.set_filled(True)
    triangle.set_color("green")
    gw.add(triangle, 250, 250)

Compound Objects

• The GCompound class makes it possible to combine several graphical objects so that the entire structure behaves as a single object
• Can be thought of as a combination of GWindow and GObject
  • You can add objects to it, but then you can also add it (and everything in it) to a window as one single object
    • This can be necessary to animate complex objects!
• Like a GPolygon, uses its own coordinate system relative to a reference point
  • When adding objects to the GCompound, you place them relative to the reference point
  • When adding the GCompound to a canvas, you set the location of the reference point

And my Axe!

def my_axe():
    def create_axe():
        axe = GCompound()
        shaft = GRect(-15, 0, 30, 300)
        shaft.set_filled(True)
        shaft.set_color("brown")
        axe.add(shaft)

        blade = GPolygon()
        blade.add_vertex(0, 0)
        blade.add_vertex(200, -50)
        blade.add_vertex(200, 50)
        blade.set_filled(True)
        blade.set_color("gray")
        axe.add(blade, -80, 50)
        return axe

    gw = GWindow(500, 500)
    axe = create_axe()
    gw.add(axe, 250, 100)

Project 2: Breakout!

Breakout History

• The popular Breakout arcade game was released by Atari in 1976
• Atari founder Nolan Bushnell wanted a new game that would build on the success of the earlier game Pong. He assigned Steve Jobs to develop the game, promising a bonus if the game required a small number of chips.
• As Wikipedia tells the story, “Jobs had little specialized knowledge of circuit board design but knew [his friend Steve] Wozniak was capable of producing designs with a small number of chips. He convinced Wozniak to work with him, promising to split the fee evenly between them.”
• Wozniak completed the game design in four days, but Jobs never told him about the bonus offer. Jobs was paid \(\$5,000\), but Wozniak received only \(\$350\).
• Jobs and Wozniak co-founded Apple Computer the following year, which has grown to be the largest corporation in the world by market capitalization.

Breakout Basics

Breakout Milestones

• Breakout is broken up over 5 milestones
• You have already seen or written pieces of similar code to many of the milestones!
  • Milestone 1: PS4 brick pyramid
  • Milestone 3: Section bouncy ball problem (this week)

Milestone 1

Milestone 2

Milestone 3

Milestone 4

Milestone 5

Representations

• For the remained of today, we want to focus on how a computer can internally store more complex and abstract information
• Initially will look at numbers
• Then we’ll segue into strings

Bit Power

• The fundamental unit of memory inside a computer is called a bit
  • Coined from a contraction of the words binary and digit
• An individual bit exists in one of two states, usually denoted as 0 or 1.
• More complex data can be represented by combining larger numbers of bits:
  • Two bits can represent 4 (\(2\times 2\)) values
  • Three bits can represent 8 (\(2\times2\times2\)) values
  • Four bits can represent 16 (\(2\times2\times2\times2\) or \(2^4\)) values, etc
• My laptop here has 16GB of system memory, and can therefore keep track of approximately \(2^{16,000,000,000}\) states!

An old code, but it checks out

• Binary notation is an old idea
  • Described by German mathematician Leibniz back in 1703
• Leibniz describes his use of binary notation in an easy to follow style
• Leibniz’s paper notes that the Chinese had discovered binary arithmetic 2000 years earlier, as illustrated by the patterns of lines in the I Ching!

Back to Grade school

Now in Binary

Representing Integers

• The number of symbols available to count with determines the base of a number system
  • Decimal is base 10, as we have 10 symbols (0-9) to count with
    • Each new number counts for 10 times as much as the previous
  • Binary is base 2, as we only have 2 symbols (0 and 1) to count with
    • Each new number counts for twice as much as the previous
• Can always determine what number a representation corresponds to by adding up the individual contributions