This is a silent tutorial video; skip to 2:10 for the juicy bit:

This is an animated wallpaper that shows your custom PNG files -- just place them in a particular folder! It also works as a screensaver. It's cpu-friendly, only drawing during transitions.

Installing

• load #photo_carousel
• mkdir /appdata/system/wallpapers
• save /appdata/system/wallpapers/photo_carousel.p64
• run the cart once, to generate the appdata folder
• cd /appdata/photo_carousel
• folder
• using your host OS, copy any PNG files into this folder (don't put them in subfolders)
• set your wallpaper to photo_carousel in System Settings

Settings

Run podtree /appdata/photo_carousel/settings.pod to edit the settings. Be sure to not press enter while editing (this crashes Picotron 0.1.0e) and you must save with the mouse, not ctrl-s (another Picotron bug(?) -- ctrl-s saves the current cart, instead of the settings file)

Set the transition time to 0 to disable transitions

Details

Converting PNGs

This cart uses importpng to convert PNG files into Picotron graphics. It does this once, in the background, and caches the results.

If you edit one of your PNGs, photo_carousel won't notice (afaik it's impossible to get last-edited time of PNGs in Picotron) Rename your file to generate a new cache entry, or delete /appdata/photo_carousel/cache.pod to regenerate the entire cache.

importpng is fast, but it's sometimes lacking in its ability to convert images into Picotron's palette. If you want better colors, you should use an external tool (like Aseprite) to convert your PNG into the base Picotron palette (you'll want the base palette, because the global palette changes to the base palette whenever you focus on some other window)

In the future I may use PNG Frame to get better colors by default, but I haven't done that work yet.

Transitions

You can add your own transitions -- you can skim through src/subdraw.lua without needing to understand anything else in the cart, and add new entries to the list of "subdraws" (transitions). Its very shadery/demosceney code

Many of the subdraws use some helper functions in src/tools.lua

Post your transition code here!

CPU usage

The cart uses about 0.002 cpu (0.2%) most of the time. During transitions, it can spike up to 25% cpu or so (depending on the transition). If you care, you can disable the transitions as a whole (by editing the settings) or individually (by editing the multi-line comments in src/subdraw.lua)

Cart

Here's the cart file. (It won't work here on the BBS, you need to download it)

photo_carousel

Cart File | Forum Post |

	More cartridges by pancelor

More Cartridges [View All]

 

photo_carousel

by pancelor

Cart #photo_carousel-1 | 2024-04-07 | Embed ▽ | License: CC4-BY-NC-SA

6

hey @zep, I've found a nasty coroutine(?)/multival bug. I'm on Linux + picotron 0.1.0d.

tl;dr: sometimes select("#",tostr(i)) is 2, possibly triggered by calling coresume() with extra args.

I ran into this initially because add({},3,nil) is a runtime error now (it used to work in PICO-8, but now it throws bad argument #2 to 'add' (position out of bounds)). I had some code: add(list,quote(arg)) that was crashing as if quote() was returning a second value for some reason, even though the code for quote() definitely returned just one value. (surrounding it in parens (to only keep the first return value) fixed my bug: add(list,(quote(arg))))

Version A of the code is very short, and trips the assert inside spin maybe 50% of the time? sometimes many runs in a row don't trigger the assert, but sometimes many runs in a row all trigger the assert. (maybe that's just statistics tho). Version B is a bit more complex but always trips the assert instantly for me.

Version A: (short, inconsistent)

printh"---"

function _init()
    local bad,good = cocreate_spin()
    fn = bad
end
function _draw()
    cls()
    local _,prog = fn(0.70)
    ?stat(1)
    ?prog or "done"
end

function cocreate_spin()
    local coro = cocreate(spin)
    return function( cpu_limit)
        if costatus(coro)=="suspended" then
            --this one breaks sometimes
            return assert(coresume(coro,cpu_limit or 0.90))
        end
    end, function()
        if costatus(coro)=="suspended" then
            --this one always works
            return assert(coresume(coro))
        end
    end
end

local total = 1000000
function spin()
    for i=1,total do
        if i%10000==0 --[[and stat(1)>cpu_limit]] then
            yield(i/total)
        end
        local n = select("#",quote(i))
        if n!=1 then
            assert(false,tostr(n).." retvals?! "..i)
        end
    end
end

function quote(t)
    return tostr(t)
end

Version B: (longer, very consistent)

printh"---"

function _init()
    poke(0x5f36,0x80) -- wrap text
    window{
        title="import png",
        width=160,
        height=64,
    }
    job = job_importpng()
end
function _update()
    job:work(0.70)
end
function _draw()
    cls()
    print(stat(1))
    print(costatus(job.coro))
end

function job_importpng()
    local coro = cocreate(pq_many)
    assert(coresume(coro))
    local job = {
        coro = coro,
        progress = 0.00,
    }
    -- returns true iff job has more work to do
    function job:work( cpu_limit)
        if costatus(self.coro)=="suspended" then
            local _,dat = assert(coresume(self.coro,cpu_limit or 0.90))
            if dat then
                self.progress = dat
                return true -- more work to do
            end
        end
    end
    return job
end

function pq_many()
    for i=1,1000000 do
        if i&2047==0 then
            yield()
        end
        pq(i)
    end
end

-- quotes all args and prints to host console
-- usage:
--   pq("handles nils", many_vars, {tables=1, work=11, too=111})
function pq(arg)
    local s= {}
        local n = select("#",quote(arg))
        if n!=1 then
            local second = select(2,quote(arg))
            assert(false,tostr(n).." retvals?: "..quote(arg).." "..tostr(second))
        end
        add(s,(quote(arg)))
        -- add(s,quote(arg))
    printh(table.concat(s," "))
end

-- quote a single thing
-- like tostr() but for tables
-- don't call this directly; call pq or qq instead
function quote(t)
    if type(t)~="table" then return tostr(t) end
    local s={}
    for k,v in pairs(t) do
        add(s,tostr(k).."="..quote(v))
    end
    return "{"..table.concat(s,",").."}"
end

As noted in Version A, the two coresume-wrapping-functions inside cocreate_spin() act differently -- I've never been able to trip the assert with the "good" version. I've tried versions of this code with no coroutines and haven't been able to trip the assert.

idk what else to say, this bug seems baffling -- sometimes select("#",quote(i)) is 2, despite quote() being a wrapper for tostr()

importpng

by pancelor

Cart #importpng-9 | 2024-04-06 | Embed ▽ | License: CC4-BY-NC-SA

18

Guide

Currently (in Picotron 0.1.0e) it's hard to use a PNG image as a sprite. You can fetch("myimage.png"), but the result isn't in the right image format. So, here's a small tool to convert PNG files into picotron sprites.

Drag any .png or .qoi image into the tool to convert it into a sprite pod on your clipboard. You can paste this into the graphics editor, or into code.

Drag in a .hex file (e.g. from lospec.com) or a .pal file (e.g. from OkPal) before importing your png to change the import palette.

Details

Import speed

This tool prioritizes import speed. Images with only a few unique colors (e.g. an image already in the picotron palette) will import much faster than images with many colors.

Color quantization

You can use any colors, and the tool will try it's best to fit them to the palette. It isn't very smart about converting colors (it uses nearest euclidean distance in RGB space, and doesn't do any dithering). If you want better color conversion, use some external tool and make sure the PNG is in the correct palette before converting it with this tool.

See also PNG Frame, in "Related tools" below.

Wallpapers

If you're making a desktop wallpaper, I think you should stick to the default palette. If you use a custom palette, then your colors will change whenever you focus some window besides the desktop, I'm pretty sure.

To make a wallpaper:

• make sure your wallpaper folder exists (mkdir /appdata/system/wallpapers)
• save a new cart into that folder with this code:

  function _draw() spr(1) _draw = function() end end

• convert your image using this tool, and copy it into your clipboard
• paste your image into sprite 1 of the default sprite file

Library usage

This code is organized to make it easy to use as a library in your code. The library is self-contained in lib/importpng.lua, and you interact with it by calling myjob = job_importpng(myimg). The returned "job" is essentially a coroutine, but one that will let you limit its processing time. Call myjob:work(limit) during _update() until the job is done, or call myjob:join() a single time to finish it all at once (likely lagging the game). See the code for more details.

License: CC4-BY-NC-SA

Related tools

• Cutievirus' PNG Frame -- a similar tool with much better color conversion. If your png is already in the right palette, importpng is faster than PNG Frame. But if you want better color quantization, use PNG Frame.
• My Aseprite PICO-8/Picotron export extension lets you export Picotron pods directly to your clipboard from Aseprite.
• My sprite importer lets you import PICO-8 spritesheets into Picotron.
• My photo carousel uses this importer to show your custom PNGs as an animated wallpaper.
• drakmaniso's OkPal palette editor.

changelog

p8x8

by pancelor

Cart #p8x8-5 | 2024-04-18 | Embed ▽ | No License

51

p8x8: convert PICO-8 carts into Picotron carts (some assembly required)

I'm declaring p8x8 good enough for public release! It's a tool to convert pico8 carts to picotron -- it's not perfect and it requires some manual intervention in most cases, but it's magical being able to play a bunch of games on the new system without much effort.

Lots more info (instructions, compatibility notes, license, etc) here: https://github.com/pancelor/p8x8/

Teaser video here: https://mastodon.social/@pancelor/112162470395945383

changelog

Here's my /appdata/system/startup.lua file (picotron automatically runs it on startup)

-- take str, delete all chars between
-- indices i0 and i1 (inclusive), and
-- insert newstr into that space
local function splice(str,i0,i1, newstr)
    return sub(str,1,max(1,i0)-1)..(newstr or "")..sub(str,i1+1)
end

-- use str:find to do sed-like file editing.
-- no lua patterns, just literal string matching
-- return str, but replace the first instance of cut with paste
local function _replace(str,cut,paste)
    local i0,i1 = str:find(cut,1,true) -- no pattern-matching
    if not i0 then
        return str,false
    end
    return splice(str,i0,i1,paste),true
end

local function sedish(fname,mods)
    local src = fetch(fname)
    if not src then
        printh("sedish: couldn't find file "..fname)
        return
    end

    for i,mod in ipairs(mods) do
        local cut,paste = unpack(mod)
        -- printh(cut.." "..paste)
        if not cut or not paste then
            printh("sedish: bad cut/paste data in "..fname)
            return
        end
        local changed
        src,changed = _replace(src,cut,paste)
        if not changed then
            printh("sedish: mod #"..i.." did nothing to "..fname)
        end
        if not src or #src==0 then
            printh("sedish: bad result in "..fname)
            return
        end
    end
    -- printh("storing "..fname..": "..sub(src,1,100):gsub("[\n\r]",""))
    store(fname,src)
end

sedish("/system/lib/gui_ed.lua",{
    { -- fix alt-tab annoyance (pressing alt-tab inserts tab character into code)
        [[if (keyp("tab")) then]],
        [[if keyp"tab" and not key"alt" then]],
    },
})

sedish("/system/apps/podtree.p64/main.lua",{
    { -- fix podtree bug (pressing enter crashes the program)
        [[if(key("shift")) return true]],
        [[if(_ENV.key("shift")) return true]],
    },
})

-- (you need to open a new gfx tab for these gfx.p64 edits to work)
sedish("/system/apps/gfx.p64/pal.lua",{
    { -- show pal numbers
        [[pcols[x + y*epr])]],
        [[pcols[x + y*epr])if pal_swatch==1 and x%2==0 then print(pcols[x + y*epr],x*ww+5,y*ww+1,0) end]],
    },
})
-- sedish("/system/apps/gfx.p64/nav.lua",{
--  { -- display sprite numbers in hex
--      [[string.format("%03d",current_item)]],
--      [[string.format("x%02x",current_item)]],
--  },
-- })
sedish("/system/apps/gfx.p64/update.lua",{
    { -- don't flip when you press ctrl-v (noticeable when undoing)
        [[if (keyp("v"))]],
        [[if (keyp"v" and not key"ctrl")]],
    },
})

sedish("/system/lib/gui_ed.lua",{
    { -- fix custom key callbacks in gui
        [[content.key_callback(k)]],
        [[content.key_callback[k](k)]],
    },
})

-- doesn't work for startup terminal
--   need to wait for it to regenerate, e.g. after running a fullscreen app
sedish("/system/apps/terminal.lua",{
    { -- add custom terminal_cd event (to let my z.lua util "run" cd for you)
        [[-- scroll down only if needed]],
        [[on_event("terminal_cd",function(msg) cd(msg.path) end)]],
    },
    { -- show slightly different terminal prompt when in upgraded terminal
        [[return result -- custom prompt goes here]],
        [[return "\f6"..pwd().."\f7 > "]],
    },
})

printh "sedish done"

what is this

I made this because picotron inserts a tab into my code whenever I alt-tab. I figured out how to edit the code editor itself to not do that, and then I made this script to automatically make the required edits. (you can't just edit the files on disk, because they get regenerated every time picotron boots)

this won't be necessary for too long hopefully, but it works great for now!

(the name "sedish" comes from the (loose) inspiration for this: sed)

post your tweaks

If anyone has other system tweaks like this one (fixing alt-tab), post them here!

update: there are basically 3 tools that are relevant here:

• this tool (sprimp) -- maybe still useful, but superceded by p8x8:
• p8x8: a tool to fully convert PICO-8 carts to Picotron carts (some assembly required) -- this grew out of sprimp
• my aseprite exporter plugin -- still useful

You probably want to check out p8x8 instead, but I'm leaving this thread as it is since it may still be useful or interesting to some people.

sprimp

by pancelor

Cart #sprimp-1 | 2024-03-18 | Embed ▽ | License: CC4-BY-NC-SA

21

tada! now you can import pico8 spritesheets. and map too!

importing a .p8 file

• put your game.p8 file somewhere inside picotron's file system
  • the filename should not have any dashes ("-"), they generally cause problems currently (picotron 0.1.0b2)
• run this importer (sprimp)
• import the p8 cart
  • you can drag-and-drop the cart onto the sprimp window
  • or you can use "Import .p8 file" in the menu (the dialog that pops up says "save as" -- please ignore this. this is the best way I know how to launch a system filepicker)

exporting sprites

• press "Save gfx..". choose a filename; the default is /ram/cart/gfx/0.gfx (which is the default spritesheet for your current cart)
• IMPORTANT: if the spritesheet was already open in picotron's gfx editor, you'll need to close the file and reopen it (right click on the tab, close, then press the plus)
• if you saved to /ram/cart/... save your cart afterwards (ctrl-s)

exporting map

• (same as exporting sprites, just click "Save map.." instead)
• for an easy transition from pico8 maps to picotron maps, check out this snippet, which includes mget and mset replacements

other ways to import (copypaste, aseprite)

future plans

changelog

susizker

by pancelor

Cart #susizker-0 | 2024-03-15 | Embed ▽ | License: CC4-BY-NC-SA

4

just a port of a tweetcart of mine to the new system :)

move this into /system/screensavers/ and it'll show up as an option in your settings

If you run it on its own as a cart, you'll want to run reset() vid(0) in the console afterwards to get things back to normal

edit: if you want it to be permanently available, you need to put it in /appdata/system/screensavers (otherwise, you need to re-add it every time you start picotron). create the folder by copying the system folder: cp /system/screensavers /appdata/system/screensavers

ghostpatrol

by pancelor

Cart #ghostpatrol-2 | 2023-10-07 | Code ▽ | Embed ▽ | No License

9

Oh no, ghosts are approaching the town!

Mayor Wombledon has begged ALFREDO THE GHOUL BANISHER to team up with THE WILY WIZ to protect the town. Can they put aside their differences and work together, or will evil spirits devour the populace?

Controls

• Arrow keys: move
• Z: swap heroes
• Enter/P: pause (level select, volume controls)
• X: next level

Outcomes

• 1 night protected: You have the villagers' sincere gratitude 🙏
• 5 nights protected: The villagers are beginning to hope again 😭
• 10 nights protected: Valiant Heroes 🏆
• 40 nights protected: Local Deity 🤯

Tips

• Alfredo can dig up graves with his fearsome claws.
• The Wiz can swap places with nearly anything.
• You can change levels freely in the pause menu.
• Never give up; always fight with your full strength.

1024 bytes, made by pancelor for PICO-1K 2023. Thanks to timp + shrinko8 for compression help!

The layouts were randomly generated, but they don't change. My best times for the first 5 levels are 7 / 11 / 15 / 39 / 41.

If you enjoyed this, you might also enjoy my game Hungry Eggbug, or the board game that loosely inspired this game: Ricochet Robots.

Hi @zep, found a parser bug for ya:

for --[[a]]e=0,1 do print(e) end
print(fore)

expected: 0 1 [nil] (this is what lua 5.4 outputs)
observed: [nil] 0

pico-8's highlighting works correctly, but the runtime seems to see this somehow:

fore=0,1

do
  print(e)
end

system: linux / pico8 0.2.5g

I ran into this while using shrinko8's annotations (for --[[preserve]]e=0,1 do)

Workaround: add an extra space (for --[[preserve]] e=0,1 do)

edit: ah! this thread has more cases / info: https://www.lexaloffle.com/bbs/?tid=51618

@zep if you open this cart in pico8 and save it, pico8 inserts an extra byte at the end (0xff) (this is wrong, but additionally it is very confusing because my text editor thinks the text encoding has changed and starts displaying weird unicode everywhere)

pico-8 cartridge // http://www.pico-8.com
version 41
__lua__
?'hi'
__meta:title__
cooltitle

After some minimal testing, the conditions necessary seem to be:

1. the file ends with a __meta__ section (__gfx__ doesn't trigger the bug)
2. the file does not have a trailing newline (the last byte of this particular file is 'e', not '\n')

platform: linux / pico8: 0.2.5g

Bitplanes are powerful, but they can be difficult to understand. How do you use them in PICO-8?

The short version: bitplanes let you draw colors to the screen without completely overwriting the existing colors, making it possible to do effects like shadows, transparency, etc. But be warned: they come with a lot of unintuitive restrictions, like monopolizing half your screen palette or requiring it to be set up in a particular way.

Longer version: PICO-8 colors are 4-bit numbers (0-15). The screen is a 128x128 4-bit image, but you can imagine it as 4 separate 12x128 1-bit images overlaid on top of each other. By poking a particular location in memory, we can tell PICO-8 to draw to these "bit planes" separately. Normally, drawing overwrites any existing colors, but if we selectively disable some of the bitplanes, some bits of the old color will remain onscreen.

Technical version: see "Technical details" below.

This post lists some specific examples and tricks that you can do with bitplanes. I won't attempt to fully explain how bitplanes work, but I'll leave some resources at the end.

Examples

Shadows

1. set up your screen palette:
   i. 0-7: shadow palette; 0 is the shadow color for 8, 1 is the shadow color for 9, etc
   ii. 8-15: any colors
2. draw anything
3. enable bitplane mode 0x08 (clear the 0/8 bitplane)
4. draw anything -- any pixels "drawn" will instead overwrite colors 8-15 with their shadow colors
5. disable bitplane mode

bitplane_shadows

by pancelor

Cart #bitplane_shadows-2 | 2023-09-21 | Code ▽ | Embed ▽ | License: CC4-BY-NC-SA

9

I used this method in my freecell clone.

Spotlight

1. set up your screen palette:
   i. 0-7: all identical; e.g. all 0 (black)
   ii. 8-15: any colors
2. draw your scene using colors 0-7. they will all appear black
3. enable bitplane mode 0xf8 (only draw the 0/8 bit)
4. draw a circfill in color 8 -- instead of drawing red, it will add 8 to each color it hits, revealing the image "underneath" the darkness
5. disable bitplane mode

This cart uses a very similar technique to create an "xray" effect. (They set up their palette differently and use a different bitplane mode, swapping adjacent colors instead of shifting the palette by 8)

1-bit sprite packing

If you have 1-bit sprites, you can store them merged in the 4 bitplanes in the spritesheet, and extract them at runtime using bitplanes. It's essentially another way to do this sprite-layering technique. Here's a tool that does something similar. Neither of these actually use pico8's bitplane feature, but they could be implemented that way to save some tokens and a tiny bit of cpu.

Chromatic aberration

You can create some cool effects (like https://mastodon.social/@zep/109315783011955478) by drawing slightly different images on different bitplanes.

Trippy motion blur

Flashing lights warning, this one can be pretty rough on the eyes. It's a neat trippy effect where each bitplane gets updated every 4 frames, leaving a slightly out-of-date impression onscreen for those other 3 frames, which creates a motion blur of sorts. I find it hard to look at (especially the jelpi example in the replies!) but it looks fascinating and it's very neat how bitplanes make it easy to create this effect in any game. I wonder how this could look with palette specifically designed for it... (the palette from the following "Anti-aliasing" example works decently well!)

(thanks freds72 for finding the link to this! I couldn't remember where I'd seen it)

Anti-aliasing

You can add anti-aliasing by drawing the same thing at slight subpixel offsets, like in this example. (Note that this restricts your palette to 5 colors)

Technical details

Wikipedia has some general info, and the PICO-8 wiki (search "bitplane") has specifics about how they work in PICO-8:

> 0x5f5e / 24414
> Allows PICO-8 to mask out certain bits of the input source color of drawing operations, and to write to specific bitplanes in the screen (there's 4 of them since PICO-8 uses a 4BPP display). Bits 0..3 indicate which bitplanes should be set to the new color value, while bits 4..7 indicate which input color bits to keep.
> For example, poke(0x5f5e, 0b00110111) will cause drawing operations to write to bitplanes 0, 1, and 2 only, with 0 and 1 receiving the color value bits, 2 being cleared, and 3 being unaltered.
> This formula is applied for every pixel written:
> dst_color = (dst_color & ~write_mask) | (src_color & write_mask & read_mask)

If you're not sure what to try, setting the write_mask and read_mask to the same value is often useful.

Other resources

-Bitwise math tutorial
-A simple bitplane example -- three circles rotating in 3D
-My bitplane explorer -- it helps visualize how colors will interact

-The original discovery
-Bitplanes confirmed by zep
-Circular Clipping Masks -- discusses other non-bitplane ways to get shadow and spotlight effects

PICO-8 supports bitplane drawing; the wiki (search "bitplane") has a description of how they work:

> 0x5f5e / 24414
> Allows PICO-8 to mask out certain bits of the input source color of drawing operations, and to write to specific bitplanes in the screen (there's 4 of them since PICO-8 uses a 4BPP display). Bits 0..3 indicate which bitplanes should be set to the new color value, while bits 4..7 indicate which input color bits to keep.
> For example, poke(0x5f5e, 0b00110111) will cause drawing operations to write to bitplanes 0, 1, and 2 only, with 0 and 1 receiving the color value bits, 2 being cleared, and 3 being unaltered.
> This formula is applied for every pixel written:
> dst_color = (dst_color & ~write_mask) | (src_color & write_mask & read_mask)

This is precise and correct, but I find it a bit hard to understand. So I made this cart to give myself an interactive sandbox where I can play around with bitplanes, to see how they affect drawing.

bitplane_explorer

by pancelor

Cart #bitplane_explorer-1 | 2023-09-21 | Code ▽ | Embed ▽ | License: CC4-BY-NC-SA

4

The code is straightforward:

1. draw the full 16-color palette
2. enable bitplanes, using the poke shown onscreen
3. draw a circle, using the circfill shown onscreen

You can change the bitplane settings and the circle's "color" -- the controls are shown onscreen. This interactively shows how drawing any color will interact with any other color under the current bitplane settings.

You'll still need to study the description from the wiki to understand how to use bitplanes, but this cart is a helpful supplement for me when working with bitplanes. I hope you find it helpful too!

update 2024: the 0.2.6 update improves things! search the update post for menuitem(0x301 for details. (My original menuitem post remains below, unchanged)

PICO-8 has fancy menuitems but there are some gotchas and bugs to be aware of.

Here's an example of what I do by default; the rest of this post will explain how the code works and why I do things this way:

menuitems

by pancelor

Cart #menuitems-1 | 2023-08-21 | Code ▽ | Embed ▽ | License: CC4-BY-NC-SA

6

L/R pitfall

Imagine you want to add a "mute" button to your game's menu. Can you spot the issue with this code?

function _init()
  menuitem(1,"mute",function()
    ismuted=not ismuted
    -- ... play/pause the music
  end)
  -- ... other game init
end

The issue: left/right can be used to change the menuitem, and left/right always leaves the menu open afterward (this may be a bug; it's unclear) so there's no indication to the player that they accidentally muted the game! It's a minor issue... but it's easy to accidentally hit left/right when navigating the menu on a gamepad, which makes this worse.

An easy fix: don't respond to L/R (menuitem(1,"mute",function(bb) if bb>=16 then ... end end)). This is what I'd recommend for games that are short on tokens but willing to spare a few to fix this.

Responsive menu

If you'd like a more responsive menu, you can do this:

function _init()
  menuitem(1,ismuted and "music: off" or "music: on",function()
    ismuted=not ismuted
    -- ... play/pause the music
    -- update the label:
    menuitem(nil,ismuted and "music: off" or "music: on") -- feels like we could save some tokens...
    return true
  end)
  -- ... other game init
end

Now the option shows its status, and updates its label immediately when you change it!

Note the return true -- this keeps the menu open. Without this, if the player presses left (toggling the setting) and then presses enter (trying to close the menu but instead toggling the setting again), they'll wonder why their change isn't sticking. By leaving the menu open, we show them that they actually re-toggled the setting, and they need to choose "continue" instead to resume the game.

Code organization idiom

The repeated ismuted and "music: off" or "music: on" is suspicious -- can we save some tokens? Yes, by setting up each menuitem() again at the end of the callback, just to refresh the labels:

function _init()
  domenuitems() -- setup all menuitem()s
  -- ... other game init
end
function domenuitems()
  menuitem(1,ismuted and "music: off" or "music: on",function()
    ismuted=not ismuted
    -- ... play/pause the music
    domenuitems() -- refresh the label
    return true
  end)
  -- menuitem(2,...
  -- menuitem(3,...
end

I do this for code-organizing reasons -- it's nice to have all the menuitem code in one place -- but it can also save a few tokens, depending on your setup.

Context-dependent menuitems

Some menuitems should only be show in certain situations -- e.g. don't show "back to title" if we're already on the title screen. You could break each menuitem into its own little setup function (like zep's original LOAD #CUSTOM_MENU cart does -- check it out, it's nice!) or do what I do: menuitem(1,condition and "label",...). This will only show the menuitem when condition is truthy. I call domenuitems() anytime the menu needs changing (e.g. at the end of init_title_screen()) and it all works out.

Recommendations / Summary

I put all my menuitem() calls inside a custom domenuitems() function. Every callback runs domenuitems() at the end, to refresh the labels.

There are three types of menu options I commonly use: commands, toggles, and selectors.

• For commands (run some code, e.g. return to the title screen), I wrap the callback code in a if bb>=16 then ... end block, to prevent L/R from triggering the command
• For toggles (e.g. mute/unmute the game), my callback always has return true, leaving the menu open afterward and avoiding the UX issue described above
• For selectors (choose a number from a range, e.g. change levels), my callback has return bb<16, leaving the menu open only if L/R were used to change the selection. (this is technically unnecessary due to a longstanding bug(?) in PICO-8's menu handling)

Read the code of the example cart at the top of this post for more info!

I often use shell scripts to export and then upload my games to itch.io, and there's a small inconvenience that trips me up sometimes: If my game is too large, the export fails, but I have no way of detecting that from my shell script.

> pico8 game.p8 -export "-f froggypaint.html"
EXPORT: -f froggypaint.html
failed: code block too large

> echo $?
0

I would expect the status code (echo $?) to be 1 or some other failure code

(Hm, now that I've written this up I suppose I could work around this by reading stderr stdout and checking for the string "failed"...)

A slow but token-efficient sort:

-- 35-token bubblesort, by pancelor
function sort(arr)
  for i=1,#arr do
    for j=i,#arr do
      if arr[j] < arr[i] then
        add(arr,deli(arr,j),i) --slow swap
      end
    end
  end
end

I did a brief speed analysis and this function seems reasonable to use for arrays up to around 50 or 100 elements, depending on how much CPU you have available to burn.

speed analysis:

cls()
function _draw()
arr={
--20,5,8,3,7,4,1,9,2,-30,
--20,5,8,3,7,4,1,9,2,-30,
--20,5,8,3,7,4,1,9,2,-30,
--20,5,8,3,7,4,1,9,2,-30,
20,5,8,3,7,4,1,9,2,-30,
}
sort(arr)
end

mildly interesting: when drawing a perfectly vertical line (line(1,1,1,h)) or perfectly horizontal line (line(1,1,w,1)), it used to be cheaper (in cpu cycles) to use rect or rectfill instead. but not anymore! I'm testing this on 0.2.5g; I'm not sure when this changed.

tl;dr: line and rectfill cost the same for orthogonal lines (rect is more expensive for vertical lines only)

simple test:

-- horizontal
prof(function()
 line(0,0,90,0,2)
end,function()
 rect(0,0,90,0,2)
end,function()
 rectfill(0,0,90,0,2)
end)
--  9+10=19 (lua+sys)
--  9+10=19 (lua+sys)
--  9+10=19 (lua+sys)

-- vertical
prof(function()
 line(0,0,0,90,2)
end,function()
 rect(0,0,0,90,2)
end,function()
 rectfill(0,0,0,90,2)
end)
--  9+10=19 (lua+sys)
--  9+22=31 (lua+sys)
--  9+10=19 (lua+sys)

full test:

function one(fn,opts)
  local fmt=function(n)
    -- leftpad a number to 2 columns
    return n<9.9 and " "..n or n
  end

  local dat=prof_one(fn,opts)
  printh(fmt(dat.lua)
    .."+"
    ..fmt(dat.sys)
    .."="
    ..fmt(dat.total)
    .." (lua+sys)")
end

function hline(x) line(0,0,x,0,2) end
function hrect(x) rect(0,0,x,0,2) end
function hrfil(x) rectfill(0,0,x,0,2) end
function vline(x) line(0,0,0,x,2) end
function vrect(x) rect(0,0,0,x,2) end
function vrfil(x) rectfill(0,0,0,x,2) end

printh"--"
for i=0,127 do
 printh(i..": ")
 one(hline,{locals={i}})
 one(hrect,{locals={i}})
 one(hrfil,{locals={i}})
 one(vline,{locals={i}})
 one(vrect,{locals={i}})
 one(vrfil,{locals={i}})
end

--[[
...
14: 
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
15: 
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
16: 
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 4=13 (lua+sys)
 9+ 2=11 (lua+sys)
17: 
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 2=11 (lua+sys)
 9+ 4=13 (lua+sys)
 9+ 2=11 (lua+sys)
...
]]

rect:
    when h is 1, sys cost is:
        max(1,w\16)*2 (agrees with CPU wiki page)
    when w is 1, sys cost is:
        max(1,(h-1)\8)*2 (disagrees? unsure)
line and rectfill
    a,b = max(w,h),min(w,h)
    when b is 1, sys cost is:
        max(1,a\16)*2 (agrees with CPU page for rectfill, but not line(?))

thetower

by pancelor

Cart #thetower-2 | 2023-07-27 | Code ▽ | Embed ▽ | No License

31

welcome to the tower
welcome to the tower
welcome ‍ to the tower
welcome to the tower

controls

• arrow keys: walk, interact
• enter: pause menu (volume, toggle effects, etc)

the game will autosave your progress each floor

credits

made by tally (art, room design, dialog) and pancelor (code, game design, music, dialog)

pixel art created with tiles from teaceratops and yelta

built with pico-8, aseprite, PX9, and shrinko8

changelog

switching between custom and default fonts (?"\015") behaves a bit strangely; the first line of text is spaced differently from the rest, depending on whether:

1. custom fonts are enabled by default (poke(0x5f58,0x81)), and
2. the line height (peek(0x5602)) is more or less than 6 (the size of the default font)

run this cart to see what I mean:

kahedapibi

by pancelor

Cart #kahedapibi-1 | 2023-01-30 | Code ▽ | Embed ▽ | No License

2

specifically:

1. when the custom font is enabled by default and the custom font's height is more than 6, the default-font text in this cart has a large gap between the first and second lines:

2. when the custom font is not enabled by default and the custom font's height is less than 6, the custom-font text in this cart has a large gap between the first and second lines:

I didn't test how ?"\^y" affects things.

my system info: 64-bit linux, pico8 0.2.5e

how many tokens should this cart cost?

s="x".."="
a=1+2

in 0.2.1b, it costs 10 tokens (5 for each line). this seems correct to me. however, in 0.2.5e, the first line only costs 4 tokens for some reason.

edit: even weirder: s="x".."=" costs 4 tokens but s="x".."y" costs 5 tokens. it seems like concatenating any string that starts with the equals symbol is 1 token cheaper than it should be; how odd! maybe this is somehow due to the recent parser updates for += etc?

When I'm making games or tweetcarts, I often adjust numbers just a tiny bit, then rerun the whole game. e.g. I change the player speed by 0.1, then change it back, then try 0.05...

This is a bit slow, so here's a library I made to help me do it faster. I also find it useful for analyzing other people's tweetcarts -- if I can easily adjust the values they use, I can quickly figure out what they mean

setup

• load #twiddler
• copy the knobs.lua + helpers tabs into your game
• use kn[1], kn[2], ... kn[8] in place of any number
• add twiddler() to the end of your _draw function

Now, run your code:

• press tab and adjust the values (see "controls" below)
• press tab again -- the values will be copied to your clipboard
• paste the values into the start of your code to save them

example 1

Start with a tweetcart you want to study. For example, this one by 2DArray: https://twitter.com/2DArray/status/1492566780451205120

?"\^!5f10◆█🐱░4웃9♥"
::_::?"⁶1⁶c"
w=t()/8
c=cos(w)
s=sin(w)
n=1800
for i=0,n do
a=i*.618
j=1-i/n*i/n
y=1+j*j-2*j*j*j
r=1-(1-j)^3+sin(a*10)/9
p=(6+sin(a*10)*(.5+r/2))*(.7+y*y/3)
circfill(64+cos(a+w)*r*20,80-y*30+sin(a+w)*r*12,2,p)
end
goto _

Add the knobs, and replace some interesting-looking numbers with knobs:

kn={.5,.7,.618,2,0,0,0,0} --changed
?"\^!5f10◆█🐱░4웃9♥"
::_::?"⁶1⁶c"
w=t()/8
c=cos(w)
s=sin(w)
n=1200 --changed -- twiddler needs a little bit of cpu to run
for i=0,n do
a=i*kn[3] --changed
j=1-i/n*i/n
y=1+j*j-2*j*j*j
r=1-(1-j)^3+sin(a*10)/9
p=(6+sin(a*10)*(kn[1]+r/2))*(kn[2]+y*y/3) --changed
circfill(64+cos(a+w)*r*20,80-y*30+sin(a+w)*r*12,kn[4],p) --changed
end
twiddler() --changed
goto _

Now run the code and play around! looks like knobs 1 and 2 control the color gradient, knob 3 controls the spiralness of the circles. cool! Add new knobs, remove old knobs, keep going until satisfied.

example 2

This process works on your own code that you're in the middle of writing, too. Write kn[1] etc instead of a number, open the knobs panel, and edit the value until it looks right:

This is from the dev process of a recent tweetcart of mine (twitter, cohost)

controls:

Press Tab or W to open/close the knob panel

• LMB - change slider value
• MMB - pan slider range
• RMB - cancel current interaction
• wheel - zoom slider range

When you close the panel (Tab/W), knob values will be copied to your clipboard -- paste them into your code to save them.

twiddler

by pancelor

Cart #twiddler-0 | 2022-10-28 | Code ▽ | Embed ▽ | License: CC4-BY-NC-SA

10

When you're done with the knobs, you can replace kn[1] etc with the literal value of the knobs, and delete the twiddler code. This is a tool meant for development, not meant to be used during a finished game. (although, a finished game that used something like this would be pretty nifty!)