load (draw)$

koordx : 4$
koordy : 4$

A : [-1,1];
B : [-1,2];
C : [1,2];

koord : [
    head_length = 0.2,           /* Pfeil-Kopflaenge */
    color = black,
    xtics = [-koordx+1, 1, koordx-1],
    ytics = [-koordy+1, 1, koordy-1],
    line_width = 2,
    vector ([-koordx, 0], [2*koordx, 0]),    /* x-Achse */
    vector ([0, -koordy], [0, 2*koordy]),   /* y-Achse */
    vector ([0, 0], [-3.5, -3.5]),   /* z-Achse */
    line_width = 1,
    xaxis = true, xtics_axis  = true,
    yaxis = true, ytics_axis  = true,
    point_type = none,
    points_joined = true,
    points ([-1.05,-0.95],[-0.95,-1.05]),
    points ([-2.05,-1.95],[-1.95,-2.05]),
    points ([-3.05,-2.95],[-2.95,-3.05]),
    label (["1", -0.8, -1.1]),
    label (["2", -1.8, -2.1]),
    label (["3", -2.8, -3.1]),
    points_joined = false
    ]$

alabel : append (["A"], A + [-0.3,0]);
blabel : append (["B"], B + [-0.3,0]);
clabel : append (["C"], C + [0.3,0]);
xlabel : append (["x"], [-3.8,-3.5]);
ylabel : append (["y"], [koordx,-0.5]);
zlabel : append (["z"], [-0.5,koordy]);

draw (
   gr2d (
     user_preamble = [
        "set noborder", 
        "set grid"
        ],
     koord,
     color = red,
     point_type = multiply,
     point_size = 2,
     points_joined = false,
     points ([A, B, C]),
     label (alabel, blabel, clabel),
     color = black,
     label (xlabel, ylabel, zlabel),
     xrange = [-koordx, koordx],
     yrange = [-koordy, koordy]
   ),

   file_name = "uebgpunkte3d2",
   dimensions = [600,600],
   terminal = png
);