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Posts tagged with code

Jun 10, 2025

ants devlog 3

this is part of a series. see the previous post here

---

let’s take the issue head on: my attempt to write this as a pseudo-tutorial has failed. i find the writing style draining, boring, forced, etc etc. worse, the more i put it off, the further i get from when i wrote the first part of my little ants simulation, so there ain’t nothing there (or at least there’s less and less there), to build on, it becomes an exercise in bland uninteresting recollection, i would prefer not to.

thus a new beginning, more honest to what i’m actually doing when i write these: let’s look at my furthest draft of the code and reconstruct together what i think my ideas were

the code itself

we’re up to some 200 lines now, so lets put these into little tabs. explanation are after our little guy here, so scroll on by for more

0: basic functions




function _init() 
   -- allow mouse :)
   poke(0x5f2d, 1)

   cur_init()
   ants_init()
   food_init()
end

function _update60()
   cur_update()
   local click=stat(34)
   --left click
   if(1==click) then
      sfx(0,-1,4)
      ants_add(cur_x,cur_y)
   end
   --right click
   if(2==click) then
      food_add(cur_x,cur_y)
   end
   
   food_update()
   ants_update()
end

function _draw()
   cls(4)
   food_draw()
   ants_draw()
   --ants_count()
   cur_draw()
end

1: cursor




function cur_init()
   cur_spr=1
   cur_x=60
   cur_y=60
end

function cur_draw()
   spr(cur_spr,cur_x,cur_y)
end

function cur_update()
   --mouse loc
   cur_x=stat(32)-1
   cur_y=stat(33)-1
end

2: ants




function ants_init()
   ants={}
end

function ants_add(x,y)
   ants[#ants+1]={x=x,y=y,age=0}
end

function ants_loop(func)
   loop_pixels(ants,func)
end

function ants_draw()
   ants_loop(
      function(ant)
         pset(ant.x,ant.y,0)
      end
   )
end

function ants_move()
   ants_loop(ant_move)
end

function ant_move(ant)
   local movement=rnd(100)
   
   if(95<movement) then
      ant.x=ant.x+1
   elseif(90<movement) then
      ant.y=ant.y+1
   elseif(85<movement) then
      ant.x=ant.x-1
   elseif(80<movement) then
      ant.y=ant.y-1
   end
   
   ant.x=loop_screen(ant.x)
   ant.y=loop_screen(ant.y)
end

function ants_age()
   ants_loop(function(ant)
         -- basic rand change to die
         if(ant) then
			local dead=
               flr(rnd(2000-ant.age))
			if(0==dead) then
               del(ants,ant)
			else
               ant.age = ant.age+1
			end
         end
   end)
end

function ants_count()
   local text="ants: " .. #ants
   print(text,2,120,6)
end

function ants_eat()
   -- we actually loop the food
   -- to easy unset it
   food_loop(function(food)
         if(food) then
			local eat=pget(food.x,food.y)
			if(eat==0) -- has ant on it
			then
               --make ant live longer
               foreach(ants, function(ant)
                          if(ant.x==food.x and 
                             ant.y==food.y) then
                             ant.age=ant.age-100
                          end
               end)
               --remove the food
               del(foods,food)
               sfx(1)
			end
         end
   end)
end

function ants_update()
   ants_move()
   ants_eat()
   ants_age()
end

3: loop helpers




function loop_screen(pos)
   if(128<pos) return 0
   if(0>pos) return 128

   return pos
   end

function loop_pixels(arr,func)
   for i=1,#arr do
      func(arr[i])
   end
end

4: food




function food_init()
   f_sprite={2,3}
   foods={}
   food_can_add=0
end

function food_add(c_x,c_y)
   --only add if not delayed
   if(0<=food_can_add) return
   
   sfx(2)
   --reset delay
   food_can_add=25
   local s_offset=
      rnd(f_sprite) * 8
   
   -- loop the sprite to add
   -- pixels
   for x=0,7 do
      for y=0,7 do
         local pix=sget(x+s_offset,y)
         if(0!=pix) then
            foods[#foods+1]=
               {x=c_x+x,y=c_y+y,col=pix}
         end
      end
   end
end

function food_draw()
   food_loop(
      function(food)
         pset(food.x,food.y,food.col)
      end
   )
end

function food_loop(func)
   loop_pixels(foods,func)
end

function food_update()
   food_can_add=food_can_add-1
end

the explanations

i like accordions. let’s do that again:

0: basic functions

this one's mostly straightforward: call the init, update, and draw functions of further tabs. in init, we poke to enable mouse use, in update we handle clicks, and in draw we clear the screen.

1: cursor

another simple one. in `init`, we set our cursor sprite, in `update` we pull in the x and y position of our cursor with inexplicable functions even _i_ dont understand (minus 1, for some sweet visual alignment tricks: it makes sure we dont hide our single pixel ants), and draw draws a sprite to the screen at that position. i think its neat. its simple. its a software sort of thing

2: ants

now we're doing something! we've got a lot here. if you've noticed, i have a tendency to order functions in a sort of least-to-most order, aka 'reverse', so let's describe them in reverse also, starting at the bottom of our code:

ants_update

the simple one: we call all the functions we write above. our ants will move, eat, then age and possibly die

ants_eat

our first hard one, in part reliable on some functions in our food tab (so read ahead!). in short, we have an array of pixels of ‘food’ as well as their x and y positions. we then read the screen data of the foods x and y coords: if its palette is 0, which is an ant, we 1) make the ant live longer by subtracting from its age value and 2) delete the food from the food array (see that tab bb). we also play a sound effect

ants_count

debug func: prints the count of ants to the screen

ants_age

we loop through our ants via the to-be-described ants_loop function and try to kill them via rng. essentially: the closer their age gets to 2000, the higher the chance they die. if they live, we age them by one, increasing their chance to die later

ants_move and ant_move

loop through and move our ants. this parts lame as hell right now, just randomizing the direction and checking to loop the screen. this’ll be a HUGE change point in our shared future

ants_draw

loop our ants and set their pixels on the screen. simple as hell

ants_loop

and you thought you might learn? no! we call a loop pixels functions on our ant, described elsewhere!

ants_add and ants_init

simple: we add an ant object at x and y in ants_add, we create a global ants array in init. this is real simple stuff, unfortunately

3: loop helpers

aint the most complicated things so simple also? `loop_screen` makes sure our position is on the 128x128 screen, `loop_pixels` takes in an array and runs a function on every member of it

why is these together, if so different? i dont’ know. i wrote this months ago

4: food

our last little bit of complexity, then we're through. You've got this, reader. I've got this, writer, too.

in init, we set up three variables. f_sprite holds a list of sprites that we can produce as food, foods holds all the food pixels we’ve set on screen (the same way we’ve set pixels for ants), and food_can_add helps us set a little delay so that we can’t just paint food across our screen

food_add adds food to the x+y off the cursor: first we made sure our food can be added by checking if our food_can_add is zero (or less---so we don’t have to worry about keeping the addable time to zero); if we’re good, we play a little sound, reset our food delay to 25 frames, then pick a sprite at random from our f_sprite variable set above. with that in place, we loop through the pixels of our food sprite and add them to our food array at the cursor location

food_draw loops these pixels to add them to the screen; food_loop makes looping these pixels easier

finally, on food_update, we count our food adding counter down one tick per frame

so: that’s a lot. its also a small bit messy, but oh well. ants are insects who live in dirt, we might as well attempt their lifestyles if we’d like to simulate

next up, back in the code for this, we’ll try to add an ability for our ants to scent out food near them and follow, as well as follow each others scents. let’s give it a go

apologies to everyone for occasionally misspelling it as ‘aunts’. i will not go back and fix this

Mar 21, 2025

ants devlog 2

this is part of a series. see the previous post here

ants

now that we have a world, let’s create life in it. because we are working with systems it seems imperative we create a model of our life cycle. thus:

→ birth
    ↪ struggle
        ↪ death

in other words, to create life true to life, we must allow our ants to live, to struggle, and to die. once we have these, we’ll have our most basic simulation

notice!

because struggle is often difficult to represent visually, we will be showing movement in its place

birth

but how will we birth our ants? ‘ants’ is of course a generalized term here, little more than metaphor, but if we follow our metaphor as example we open ourselves to a whole complex reproduction apparatus, queens and soldiers and social roles and all, which is more than we are ready to simulate now. we’ll need another way to birth them, with an artificially increased control

a shame: we must reveal ourselves so early

revealing the creators hand

pico-8 offers optional mouse cursor support. it’s a sort of imitation secret, in that only its implementation seems obscure, its existence is known by most who use the program. also, more relevantly, it seems the perfect way to spawn out ants: use the mouse to select a pixel, click, and bring a single ant to life

to enable the mouse, we need only call the below function somewhere in our program. don’t worry what it means now. the meanings mostly unimportant ¹

 poke(0x5f2d, 1)

at least now we have a use for our _init() function: to init our cursor. let’s put that at the top of our file:

function _init()
	poke(0x5f2d, 1)
end

try to run it now? does anything happen? no: we need to make our hand

revealing the creator’s hand, pt 2

hi! my name is j konger. its a pseudonym, of course. few parents give their child a single initial name. i had the idea this devlog would be fun to write in the voice of a tutorial, but the more i write on this the more i realize i need to drill down, explain things neither you or i find very interesting. instead of scrapping this work however (in accordance with my site’s first rule), i am changing course into simple narrative. i hope you don’t mind.

a shame: we must change our course so early

cursor

code

this is the image i used for my cursor. you’ll notice it’s the pico 8 cursor almost exactly, with the color changed. we’ll get to that later, maybe several posts from now

and this is the code i used to make the cursor follow the mouse, which i put in a separate tab:

-- cursor

function cur_init()
	cur_spr=1
	cur_x=60
	cur_y=60
end

function cur_draw()
	spr(cur_spr,cur_x,cur_y)
end

function cur_update()
	--mouse loc
	cur_x=stat(32)-1
	cur_y=stat(33)-1
end

and, under our main tab, we now have this:

function _init() 
   -- allow mouse :)
   poke(0x5f2d, 1)
   cur_init()
end

function _draw()
	cls(4)
	cur_draw()
end

function _update60()
   cur_update()
end

explanation

let’s start with that second part of code, as its simplest: for readability, we add a new init, update, and draw function to our cursor, then just call them in the generic version of each. we call this ‘separation of concerns’. we call this ‘elegant code’

the other tab is simple also, just not as much. let’s go function by function, ok? i think that sounds nice:

cur_init

here, we just set some defaults. cur_spr is the index of our sprite, cur_x and cur_y the starting position of our cursor, which we add only because we need to call it in…

cur_draw

here were merely draw the sprite to screen: spr() draws a sprite, and cur_x and cur_y tell it where to go, x- and y-wise. as we’re using the mouse here, we are continuing to use obscurant functions. all we need to know for our purposes is that stat(32) returns our cursor’s x coordinate, stat(33) its y, and that we subtract one pixel distance from each so our cursor points at the coordinate rather than overlaps, thus looking overall more ‘real’ to our precious user (in truer words ‘familiar’)

end

so now we have a hand in our own creation. if nothing else, that’s worthy of our pride. reach out now, with your pointer device of choice, and touch your world. hit ctl-r on your keyboard to run the app and watch the cursor move

full code and downloads

cartridge

(right click to save, open in pico-8)

full code

-- ants
-- by j konger

function _init() 
   -- allow mouse :)
   poke(0x5f2d, 1)
   cur_init()
end

function _draw()
	cls(4)
	cur_draw()
end

function _update60()
   cur_update()
end


-->8
-- cursor

function cur_init()
	cur_spr=1
	cur_x=60
	cur_y=60
end

function cur_draw()
	spr(cur_spr,cur_x,cur_y)
end

function cur_update()
	--mouse loc
	cur_x=stat(32)-1
	cur_y=stat(33)-1
end

i’d like to have embeds here in a later post, once i figure out how to do that with my static site generator. perhaps that will exist by the time the game gets interesting




---




Footnotes

1. ok, you wanna know? here’s the explanation i used to learn it ↩

Jan 30, 2025

ants devlog 1

to live is to struggle, of course, as well to die; pico-8 is a fantasy computer console.

in pico-8 i am simulating bugs. it is clear they aren’t actual bugs, but bugs are the smallest creature i’ve seen that was also living (in high school, with microscopes, we made the bacteria die). therefore i am calling my creatures bugs, as a tip of the hat to the fact that they are living (or in other words outside of my control)

world

first we must create a world for them to live in. pico8 offers three default functions, _init(), _draw(), and _update() (or, in our case, the closely related _update60() to do something similar in 60fps) to simulate our world, so let’s start with these

_init() creates our world. at the moment we will be existentialists and encounter it as given. thus we will not touch upon it now

_update60() creates action in our world. now, as perhaps idealists, we will ignore this for now.

_draw() in fact is all we need to create our world. software after all is not concerned with reality, only representation, thank god. thus, we need only add the color of dirt to our draw function, as dirt is the insects’ natural home. pico-8 uses a integer index-based color palatte, so let’s draw with that now:

function _draw()
    cls(4)
end

what does this mean? _draw(), run every frame, will create an image of all we’ve made. within in, cls() paints the screen a single color ¹, which we’ve set to 4, in other words brown, the color of earth

every second, in other words, we will be reminded the earth is brown. i find this wonderful

our world so far: so much dirt

Footnotes

1. clears the graphics buffer, so to say ↩