runtime problem with metafun() code

[Peter Rolf <indiego@gmx.net>]

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Hi,

I try to create a Metapost path in lua and it works so far for the
attached example. But a call of that function from another lua function
sadly fails (no path visible after call). The code seems to be executed
later (the output from 'show pid;' appears somewhere later in the log).

How can I ensure that the code is executed at runtime?


Peter

[-- Attachment #2: mplua.lua --]
[-- Type: text/x-lua, Size: 1157 bytes --]

thirddata            = thirddata            or { }
thirddata.drops      = thirddata.drops      or { }

local drops = thirddata.drops

local metafun = context.metafun

local format,todimen = string.format, string.todimen
local floor = math.floor

-- http://lua-users.org/wiki/SimpleRound
local function round(num, idp)
    local mult = 10^(idp or 0)
    return floor(num * mult + 0.5) / mult
end

function drops.numberofpixels(n,idp)
    local dimenfactor = 1/tex.pdfpxdimen
    return round(todimen(n)*dimenfactor,idp)
end

local numberofpixels = drops.numberofpixels


function drops.generate_default_path(id,width,height,radius)
    local w,h,r
    w = numberofpixels(width); h = numberofpixels(height); r = numberofpixels(radius)

    metafun.start()

    metafun("save p,pid; path p; string pid;")

    -- metafun("id := \"drops:boxshadow_w%sh%sr%s\";",w,h,r)
    metafun("pid := \"%s\";",id)
    --metafun("show pid;") -- ok
    metafun("p:= unitsquare xyscaled(%s,%s) smoothed %s;",w,h,r)

    metafun("passvariable(pid,p);")
    metafun("setbounds currentpicture to boundingbox(p);") -- 'activator'; void graphics are ignored

    metafun.stop()
end

[-- Attachment #3: mplua.mkiv --]
[-- Type: text/plain, Size: 235 bytes --]

\ctxloadluafile{mplua}{}


\starttext
\ctxlua{metapost.showlog = true}

\ctxlua{thirddata.drops.generate_default_path("drops:boxshadow-w199h100r10","200pt","100pt","10pt")}
\ctxlua{inspect(metapost.variables)}



\stoptext

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