/*
JD 12 May 2013
*/
// < • P R E P A R A T O R Y  S T U F F • >
var std_screen = 96, // pixels per inch
px2mm = function(mm) {return mm * std_screen / 25.4},
w = 254, h = 132.3, scale = px2mm(1),
vflip_all = " matrix(1 0 0 -1 0 " + h + ") ",
vflip_text = " matrix(1 0 0 -1 0 "+ h + ") ",
svg = d3.select("body").append("svg")
    .attr({"width": w * scale, "height": h * scale}),
background = svg.append("rect") .attr("id", "background")
    .attr ({"y": 1 * scale, "width": scale * (w - 1) , "height": scale * (h-1)}),
g0 = svg.append("g") .attr("id", "g0")
  .attr("transform", "scale(" + scale + ") " + vflip_all);
 // • E N D  O F  P R E P A R A T O R Y  S T U F F • >


// ——————————◊——————————— S E E S A W  S T U F F ———————————————◊——————

var run = function(tim) {
	
var seesaw_length = 110, seesaw_centre = Math.random() * seesaw_length;
 
var g_seesaw = g0.append("g") .attr("id", "g_seesaw")
	.attr("transform", "translate(" + (w/2) + " " + ( 1/2 * h) + ")")
	
var seesaw = g_seesaw.append("path") .attr("id", "seesaw")
	.attr("transform", "rotate(35)")
	.attr("d",
        "M " + (-seesaw_centre) + " 0, h " +
        (seesaw_centre - 2) + "a 2 2,0 0 0,4 0, \
        a 2 2,0 1 0,-4 0, m 4 0, h " +
        (seesaw_length - seesaw_centre - 4) + " 0")
	.transition()
		.ease("linear")
		.duration(tim)
		.attr("transform", "rotate(-35)")
this;
}

background .on("click", function() {seesaw.remove(); run(1700); this} ); 
run(6000);