%D \module
%D   [       file=meta-imp-meshes-demo,
%D        version=2026.06.09,
%D          title=\METAPOST\ Graphics,
%D       subtitle=3D Plug-in Demo,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

%D This is a simple demonstration of how to plug code into the 3D generator. You can
%D find some examples in the other \typ {meta-imp-meshes-*.mkxl} files.

\startluacode

metapost.registermesher("demo", function(specification)
    return {
        name      = "demo",
        id        = specification.id,
        vertices  = {
            { 1, 1, 1 }, { 3, 1, 2 }, { 3, 3, 3 }, { 1, 3, 3 },
        },
        meshtype  = 7,
        -- [1 2 3] [ 1 3 4 ] [5 6 7 ] 5 7 8 ] ...

    }
end)

\stopluacode

\continueifinputfile{meta-imp-meshes-demo.mkxl}

\setupbackgrounds
  [paper]
  [background=color,
   backgroundcolor=darkblue]

\starttext

\startMPpage

    lmt_scene_start [
        bytemap      = 34,
        width        = 100,
        crop         = true,
        supersample  = 4,
        projection   = "perspective",

        eye          = (-2,-2,1),
        target       = (0,2,1),

    ] ;

    lmt_scene_material [
        name      = "surface",
        diffuse   = (1,1,0),
    ] ;

    lmt_scene_internal [
        id       = "one",
        name     = "demo",
        material = "surface",
    ] ;

    lmt_scene_render ;

    drawdot (lmt_scene_point (1, 1, 1)) withpen pencircle scaled 1 withcolor darkred ;
    drawdot (lmt_scene_point (3, 1, 2)) withpen pencircle scaled 1 withcolor darkred ;
    drawdot (lmt_scene_point (3, 3, 3)) withpen pencircle scaled 1 withcolor darkred ;
    drawdot (lmt_scene_point (1, 3, 3)) withpen pencircle scaled 1 withcolor darkred ;

    lmt_scene_stop ;

\stopMPpage

\stoptext