This is-- oop, you're a little cut off there.

This CS50 on Twitch.

My name is Colton Ogden.

I'm joined briefly by--

DAVID MALAN: David Malan.

Nice to see everyone again.

COLTON OGDEN: Today we're doing--

well, first of all I should say happy Thanksgiving, happy late Thanksgiving.

Hope you enjoyed your holiday if you were celebrating Thanksgiving here

in the US or abroad.

We had a bit of a weekend here but we're back.

We're streaming today.

I just came back.

I'm a little tired.

I don't know about you.

Did you enjoy your Thanksgiving?

DAVID MALAN: I'm very rested, ready to start the day.

COLTON OGDEN: Ready to start the-- you have the hackathon this week.

DAVID MALAN: Indeed.

COLTON OGDEN: CS50 Hackathon.

DAVID MALAN: CS50's all night hackathon, 7:00 PM

to 7:00 AM later this week on campus.

COLTON OGDEN: Yeah.

So that'll be a good time, an all nighter with IHOP

and a bunch of other stuff.

Today on Twitch what we're going to do is

a from scratch implementation of Space Invaders.

Did you play Space Invaders when you were--

DAVID MALAN: I did.

When I a kid this was the state of the art.

Space Invaders probably came out a few years before I really got into games,

but this was high tech.

COLTON OGDEN: Yeah, this was-- oh, and thanks Jumpjump123 and Lifedevourer22

and DZsniper.

I saw that you guys followed before the stream began, so thank you very much.

But yeah, so we're going to do a from scratch using Love and Lua,

just kind of like how we did Snake and how we did Memory Game,

and what was the-- we did one last one that I can't remember.

Having a brain fart.

But yeah, so I'm going to jump to my laptop.

DAVID MALAN: I'm going to jump out, but I'm

going to hop into chat later and stay in touch.

COLTON OGDEN: Cool, cool.

Thanks a lot.

DAVID MALAN: Good too see everyone.

COLTON OGDEN: All right.

Oh, and this is funny.

You'll like this, by the way, before you leave.

I made the mistake, and everyone else from Twitch can enjoy this.

I'm wearing a green shirt.

So I am wearing an invisible shirt today.

DAVID MALAN: Oh, this is great.

So we could actually see things through you.

COLTON OGDEN: Yeah, exactly.

A little bit less screen coverage of me, more of the screen.

DAVID MALAN: Such a professional.

OK, on that note.

COLTON OGDEN: But yeah, that was a funny thing

I realized when I was coming in here to set the green screen up.

Let me just say hello to everybody before we actually begin.

I know we had quite a few people in the chat prior to everything starting up.

So, [INAUDIBLE],, Bavich_knight, Forcelnight, Fatma, Brenda,

Realcuriousqe, thank everybody who--

all the regulars I see are here.

Nishthegamer, hello!

Bavich_knight, hello!

Rajeshcanonrk, I think I have seen that name before.

Correct me if I'm wrong.

Good to see you.

Cloudxyzc definitely has been here before, hello.

Nuwanda3333 is [INAUDIBLE] and Goal1.

So thanks everybody who is already here.

So yeah, Space Invaders!

This is going to be fun.

So, Space Invaders we actually taught in the games course that I teach, GD50.

It was a project that we implemented.

We ended up scrapping the project idea from the course

for the second iteration of it just because it was a bit too much work.

But it's a great game because it's similar in some ways

to Breakout which we teach just prior to that,

because it's kind of this vertical oriented game

where you play as a spaceship that shoots up

towards the top of the screen.

And Breakout is a game where you're a paddle that moves left to right

and you bounce a ball back up to the top of the screen.

So I sort of feel like the two games were sort of related in a sense.

I think certainly the folks that implemented Space Invaders probably

played Breakout and were inspired.

And Breakout I do believe was implemented by Steve Wozniak

although I'm not 100% sure on that.

So let's do a quick old Wikipedia and just verify whether that's true.

Breakout the game which is here--

so it's by Atari.

I know that he implemented the Apple II version.

I'm not 100% sure if he--

oh yes, Steve.

So he did design breakout for Atari.

And then he implemented it for the Apple II.

And from what it says here, it was a big influence on the actual architecture

of the Apple II.

So gaming has a huge influence in the history of personal computers as well.

Inolove19 watching from the Philippines, thank you very much for tuning in.

I would like to read your comments [INAUDIBLE]..

I'll try to comment as much as I can.

What did I miss?

I opened and David was already leaving, says Aslee.

Yeah, you missed-- unfortunately he made a brief appearance and you missed it.

But surely we'll get him on stream again, maybe next week even.

Jebcochasin says, what are--

I apologize if I'm mispronouncing that name.

It could be Yobcochasin or Yobcochosin.

What are we going to do today?

We're going to implement Space Invaders from scratch.

So if you're unfamiliar, in prior streams

we've used a framework called Love2d and a language called Lua.

So you can download the framework Love by going to Love2d.org.

So I'm just going to go straight to that main page.

And for whatever operating system you're using you can download it,

if you're Windows, Mac, Linux, or otherwise.

And you can download prior versions, newer or older versions.

It's a super nice, super easy to use framework

that gives you a lot of abilities to do drawing and input and sound

and all kinds of other stuff.

So we'll be using that.

I'm sort of going to be assuming that you've maybe watched the prior streams.

But we'll still take it fairly slow so that folks

that are tuning in for the first time can follow along

without too much difficulty.

But definitely if you haven't downloaded the framework yet, download it here.

It's going to download an executable that you will then

use to run game code.

And if you go to the wiki page which is at the top right,

you go to this getting started page.

This getting started page will tell you, depending

on what operating system you're running, how to actually run your game.

So if you're on a Windows machine for example,

usually the easy way would be clicking and dragging your game folder

onto the executable or the shortcut.

But there are other ways to do it.

If you're on a Linux or a Mac machine, you

can alias the location of the actual executable file and then call that.

I have it set up so that in my terminal, for example--

I'm going to clear this--

I can just type love dot like that.

And that will actually call the love executable

and run it with dot, which is the current directory that I'm in.

So if I'm in a directory that has a main dot Lua, this will work.

It won't work right now because I'm not in a folder that actually has that.

So by default, if you just type love or type the path

to where it is on your machine and you have it actually there,

you should get a box that looks something like this with a balloon--

if you're running 11.1, with a balloon and a scrolling background.

So that's Love.

That's sort of the basics of how to actually find

it and get started with it.

Thanks for this game.

It's one of my favorite games, says Goal1.

Yeah, it's an awesome game.

I love the Breakout pset of old, says Bavich_knight.

Yeah, it was a great pset.

And I remember, I contributed a little bit to that pset as well.

That was right when I started working for CS50 roughly.

We had a laser part of that pset if you remember that,

and that was the part that I contributed.

Hi everyone's, says Lintzpotaguara.

Hey, Lintz, thanks for joining us.

Taking CS50, this is my first time watching your stream,

says Jacobchaussen.

Yes, thank you very much for joining.

So typically what we do is, we have a bunch of people come in,

people that work with CS50, myself included.

And we usually implement something from scratch from the ground up

or we'll take a look at something and we'll

cover a broad overview of that subject.

For example, Nick Wong has come on to talk about Linux commands

and machine learning.

And we've had Veronica talk about Python.

David's come on to talk about regular expressions and going from C to Python.

So we cover a bunch of stuff.

I focus on game development so if you like games, yeah, game programming,

tune in to my streams.

And I also co-host with everybody else that

comes in to sort of give a little bit of a conversational feel to the stream.

And I notice the camera shot is a little bit lower, too,

today so you can actually see the top of my laptop.

You can see I have an Inn and Out sticker representing

my home state of California.

Virtual office hours, says Fatima.

Yes, very much so.

Hanscost, hi everyone from Italy.

Thank you so much for joining us all the way from Italy-- super awesome.

Every time somebody in the chat says that they're from some place

abroad, someplace that's not in the United States,

it's just such a cool feeling to know that everybody around the world

is tuning in-- especially considering how late it probably

is over there right now.

Although maybe in Italy it's not so bad.

I think in the Philippines, or was it somewhere else,

it was like 2:00 AM or 3:00 AM typically for a lot of these streams.

Curase is from Italy as well.

Jakobchaussen just signed up, yeah.

Thank you so much.

First stream ever on Twitch, wow.

We got some new people in today.

This is exciting.

All right, so Brea--

not Breakout.

Breakout is the game that we were comparing Space Invaders to.

We want to actually take a look at Space Invaders.

Thank you very much, Fearblaise, for following.

So, Space Invaders was I think one of the first big arcade

games that came out.

And this was around the era where arcade games were kind of like the games

to go play.

There weren't really very many home consoles.

Although in 1978 you did have the Atari 2600 which was a very big home console.

But just prior to this for several years there

were very much not any console games.

It was all arcade games.

So if you wanted to play Pong for example, or other games--

typically Atari was the big contender in this era,

although other companies came out.

Whoever made PacMan, I forget offhand, that was a huge one.

PacMan was Namco.

And that was in--

oh, that was in 1980 actually.

I apologize.

So that was actually afterwards.

But this era, the early '70s until the '80s

and going into the '90s even a bit, was dominated by arcade machines.

But as the '90s came about, arcades went the wayside and now arcades are very

rare and almost like novelty--

not novelty.

They're the opposite of novelty--

antiquated.

And therefore they have this particular unique value to them.