(* An animation of contravariance. *)

module Contra
import Circle;

let g = graph_new();

let genSets =
  proc(col)
    let aSet = Circle_circle(g, 0.25, 0.5, 0.3, 0.01, col);
    let bSet = Circle_circle(g, 0.75, 0.5, 0.2, 0.01, col);
    let aTop = graph_newVertex(g);
    graph_moveVertex(aTop, 0.25, 0.35, false);
    let aBot = graph_newVertex(g);
    graph_moveVertex(aBot, 0.25, 0.65, false);
    let bTop = graph_newVertex(g);
    graph_moveVertex(bTop, 0.75, 0.4, false);
    let bBot = graph_newVertex(g);
    graph_moveVertex(bBot, 0.75, 0.6, false);
    let abTop = graph_newEdge(aTop, bTop);
    graph_setEdgeColor(abTop, color_named("black"));
    graph_setEdgeArrows(abTop, false, true);
    let abBot = graph_newEdge(aBot, bBot);
    graph_setEdgeColor(abBot, color_named("black"));
    graph_setEdgeArrows(abBot, false, true);
    {aSet=>aSet, bSet=>bSet, 
     aTop=>aTop, aBot=>aBot, bTop=>bTop, bBot=>bBot}
  end;

let abPrimeSets = genSets("red");
let abSets = genSets("blue");
(* graph_vertexToFront(abSet.bSet); *)

let r = proc() graph_redisplay(g) end;
let h = proc() graph_hide(g) end;
let a =
  proc()
    abPrimeSets.aSet.move(0.25, 0.5, 0.2, true);
    abPrimeSets.bSet.move(0.75, 0.5, 0.4, true);
    graph_moveVertex(abPrimeSets.aTop, 0.25, 0.4, true);
    graph_moveVertex(abPrimeSets.bTop, 0.75, 0.3, true);
    graph_moveVertex(abPrimeSets.aBot, 0.25, 0.6, true);
    graph_moveVertex(abPrimeSets.bBot, 0.75, 0.7, true);
    graph_animate(g, 0., 5.);
    
    abPrimeSets.aSet.move(0.25, 0.5, 0.3, true);
    abPrimeSets.bSet.move(0.75, 0.5, 0.2, true);
    graph_moveVertex(abPrimeSets.aTop, 0.25, 0.35, true);
    graph_moveVertex(abPrimeSets.bTop, 0.75, 0.4, true);
    graph_moveVertex(abPrimeSets.aBot, 0.25, 0.65, true);
    graph_moveVertex(abPrimeSets.bBot, 0.75, 0.6, true);
    graph_animate(g, 0., 5.);
    
  end;

graph_show(g);

pause(5.0);

a();