Hi all,

I'm writing a short graphical text adventure for the PICO-8, and a few weeks ago I determined that I needed a vector graphics editor capable of outputting PICO-8 code. I've created a web app called GMagic that lets you make vector drawings on a canvas, then export Lua functions for drawing them. I also provide the functions for drawing polygons and polylines:

ptstr() (needed for the functions):

function ptstr(s)
    local data={}
    local wip=''
    for i=1,#s do
        r=sub(s,i,i)
        if(r==',') then
            add(data,wip+0)
            wip=''
        else
            wip=wip..r
        end
    end
    add(data,wip+0)
    return data
end

Polygon:

function poly(r,c,p)
    local t=ptstr(r)
    --based off alienryderflex.com/polygon_fill
    --t=table x1,y1,x2,y2...
    --c=colors (hex)
    --p=pattern
    local pc=#t/2
    local px={}
    local py={}
    local my=127--miny
    local xy=0  --maxy
    --split out xy lookups
    for i=1,#t-1,2 do
        add(px,t[i])
        add(py,t[i+1])
        if(t[i+1]<my) my=t[i+1]
        if(t[i+1]>xy) xy=t[i+1]
        if(i<#t-2) then
            if(p) fillp(p)
            line(t[i],t[i+1],t[i+2],t[i+3],c)
            fillp()
            --yield()
        end
    end
    --scan down the screen
    for y=my,xy do
        local nx={}
        --build a list of nodes
    local n=0
    local j=pc
    for i=1,pc do
        if((py[i]<y and py[j]>=y)
            or(py[j]<y and py[i]>=y)) then
            add(nx,(px[i]+(y-py[i])/(py[j]-py[i])*(px[j]-px[i])))
        end
        j=i
    end
    --bubblesort nodes
    local k=1
    while(k<#nx) do
        if(nx[k]>nx[k+1]) then
            nx[k],nx[k+1]=nx[k+1],nx[k]
            if(k>1) then
                k-=1
            end
        else
            k+=1
        end
    end
    --fill the pixels
    for l=1,#nx-1,2 do
        local d=nx[l]
        local e=nx[l+1]
        if(d>=127) break
        if(e>0) then
            if(d<0) d=0
            if(e>127) e=127
            if(p) fillp(p)
            line(d,y,e,y,c)
            fillp()
        end
    end
 end
 --yield()
end

function pline(r,c,p)
    local t=ptstr(r)
    for i=1,#t-2,2 do
        if(p) fillp(p)
        line(
            t[i],
            t[i+1],
            t[i+2],
            t[i+3],
            c
        )
        fillp()
    end
    --yield()
end

If you want to read more about GMagic or check out some sample screenshots, you can view the Github repository here. If you end up using GMagic for a cart, I'd love to hear about it!

EDIT 6/24: I can't believe I forgot to include ptstr()! I've added it above, and to the Lua sample in the repo.

This looks way cool! I'm interested in using this because I'm annoyed with trying to do it all with the built in line() function, but when I ran it in Pico 8 the ptstr() function throws an error: I'm not sure where it's expecting that to come from.

Very cool.

Was about to say this would be useful for an adventure game engine, then I see you're doing just that! 😁

YES! this is awesome.

Hey all, sorry I forgot about ptstr()! I've updated the main post, it's just a function that divvies up a comma-separated string of points. That way your shapes can count as one token each.

Wow this looks like the drawing style of early graphic adventure games! Cool idea!

I LOVE THIS tool. Ago you think you could add RECT and CIRC to the web app? I could obviously see this tool ballooning out of control, but at least circles would add an art layer that's pretty important.

Did you ever make this tool specifically to run in Pico-8 ?

Just discovered this and think it's great!
Is it still being worked on?

Just a couple of things:
The points are big when trying to draw some little detail. It'd be great if they went to big pixels rather than boxes when not being edited.
It's be flippin' great if you could load a backdrop picture in to trace around.

Other than that. Love it.