(* An example of mouse detection. *)

let g = graph_new();
graph_setWorld(g, ~5.0, 10.0, 10.0, ~5.0);

let v1 = graph_newVertex(g);
graph_moveVertex(v1, 1.0, 1.0, true);
graph_setVertexSize(v1, 1.0, 1.0);
let v2 = graph_newVertex(g);
graph_moveVertex(v2, 4.0, 4.0, true);
graph_setVertexSize(v2, 1.0, 1.0);
let e = graph_newEdge(v1, v2);
graph_setEdgeColor(e, color_named("red"));
graph_setEdgeArrows(e, false, true);

graph_show(g);

let a = proc() graph_animate(g, 0.0, 1.0) end;

pause(2.0);

a();

graph_setClickAction(g,
  proc(g,x,y)
    let vs = graph_verticesAt(g, x-0.1, x+0.1, y-0.1, y+0.1);
    if #(vs) > 0 
    then
      graph_removeVertex(vs[0]);
      graph_redisplay(g);
    end
  end);