Creating objects using tables in Pico-8

This tutorial looks at how to create objects such as bullets and particles using a table. The objects can look after their own update and draw functions and can be created easily.

[DanielGilchristYT]

These are exactly the types of videos I needed when I started out with Pico-8! I really like the approach of isolated topics within each video, and aside from that, you are clear and concise. There is a lack of this kind of tutorial content for Pico-8 on YouTube and hopefully your channel will fill that niche. Great stuff!

[nclrdy]

I have been dabbling around with Pico-8 for a while now. Never made any games really. Just trying to use it as a learning tool for programming concepts. And I could never wrap my head around how to use tables. Especially for "instancing" objects like projectiles or other things. And this REALLY gave me the ah-ha! Moment I needed. Thank you so much for this short, yet very concise video about that topic.

Now I just need to understand collisions and using them to affect objects.

[Cerbyo]

incase anyone else is confused with what "b" is about:
i.e. for b in all(bullets) do...
Basically this is saying for every item in the table 'bullets', assign the items of this table to a variable we defined as b, and then do the following to it ( i.e. b:update() etc....). In other words you can rename 'b' to anything u want. So this might not work as intended if you store other other objects like 'health' or whatever in the same table, since everything item with a function named update() gets called.

[dieterhorvat]

This is an excellent video! This perfectly explains something I've been having trouble with!

[anmeldungscrack]

Just wanted to say thank you! This is insanely informative and on point. I also like your voice. Very calming :) Keep up the good work!

[stasoline]

This and the "managing game state" videos have been so valuable for me starting out. My code is so well-structured thanks to you! 💪

[bub]

i didnt know you could put functions inside of tables my mind has been expanded and ive been doing everything wrong

[Stripehat]

Been trying to understand this for ages. Thank you!

[diceman]

Thanks a lot for this! For one like me, who comes from procedural BASIC-Programming, the concept of tables was hard to grasp. I mean, in PureBasic I do have stuff like Structs and Linked Lists, and I know how to manipulate them, but this was a different beast altogether. After watching your tutorial, though, it became a lot clearer.

[Cerbyo]

--Bullet timer:
h=0
bullet_timer = false

if btn(5) then
if h == 0 then
bullet_timer=true
add_new_bullet()
end

function _update()
bullet_delay()
...
end

function bullet_delay()
if bullet_timer then
h+=1
if h>8 then
h=0
bullet_timer=false
end
end
end


So basically a boolean is used as a switch here (bullet_timer). the contents of the function bullet_delay become active when this switch is turned to true. What the function then does is it increases h over time (can play with the values as u like). Once h hits a certain number, we set h to 0 and turn the h timer off. Then it allows btn(5) when pressed to activate add_new_bullet once again cause h =0 like it was originally in init before any bullets were first added.

[Akita_NeruDen]

thank you so much for this this has help me make so many games.

[VileoSufora]

Amazing tutorial, as always. I was coming into this thinking I'd know everything already, but I was entirely unprepared for being able to put FUNCTIONS into objects. Not that I'm an expert, but I had read the documentation and, as far as I could tell, it makes no mention of this function-ality (ha). I'm going to have to revamp a couple of my projects to use this knowledge now.

[jacekbecela]

Quality content here. You are a good teacher!

[ossoace]

Wow! I've been trying to do this!

[axi]

Thanks a lot for this tutorial, it really helps with my work, otherwise, it would take ages for me to get a grip on this topic.

[RobUttley]

Ah, and now the state video (later in the sequence) makes more sense, functions and code as variables - a bit like closures, really - thanks! 
I should have watched these very recent ones in strict order :-)

Great explanation, by the way, very easy to follow and grasp.

[koalo]

thank you so much for this tutorial! perfect video

[that_bean]

Could you use btnp to space out the bullets?

[that_bean]

Anyone know why mines saying self is a nil value?

[Jake-zpxg]

@doc_robs thank you for the wonderful tutorial series!

However, I do have a question regarding collision. I have followed both this tutorial and the fget mget collision tutorial. I have attempted to combine the two but when I try to return the X, Y, W, H to the collision i am receiving runtime error at IF HIT(X+DX, Y, W, H) THEN. "ATTEMPT TO PERFORM ARITHMETIC ON GLOBAL 'X' (A NIL VALUE)". Is this because the object BULLET has no way to index values?

Any help would be greatly appreciated.

Cheers!