On 1/25/2014 1:58 PM, Peter Rolf wrote:
Am 25.01.2014 01:07, schrieb Hans Hagen:
On 1/24/2014 7:41 PM, Peter Rolf wrote:
Am 24.01.2014 14:45, schrieb Hans Hagen:
On 1/24/2014 1:35 PM, Peter Rolf wrote:
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?

I don't understand the issue but isn't there a

      metafun("draw p;")

missing then?

Setting the bounding box has the same effect, as drawing something.
Both methods avoid that the emtpy graphic is ignored by ConTeXt.

Anyhow, the MP path is not available in metapost.variables after the
function call. If there is no other way I have to call the function from
the TeX side (like in the attached example). Will look into that
tomorrow.

%D We also provide an outputless run:

\unexpanded\def\startMPcalculation

I tried that command, but couldn't get it to work on the lua side.

The first pure MP line after context.startMPcalculation() raises a lua
error and a combination with metafun() is also not working. So how to
use this in lua?


Anyhow, the problem is the execution time of the MP graphic. I changed
the attached example a bit, so that you can see it.
The inspect() in drops.foo() gives an empty table, while the second
inspect on the TeX side shows the path "drops:foo".

I need the path right after the call (it needs to be adapted to IM
afterwards; mainly scaling and shifting). Is there a way to "force" the
execution of the graphic without switching back to the TeX side?


function drops.foo(id,width,height,radius)
    drops.generate_default_path(id,width,height,radius)
    context(function() inspect(metapost.variables) end) -- empty here
end

or

function drops.bar()
    inspect(metapost.variables)
end

function drops.foo(id,width,height,radius)
    drops.generate_default_path(id,width,height,radius)
    context(drops.bar) -- empty here
end


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                                          Hans Hagen | PRAGMA ADE
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