Craftyjs canvas rotation

Question

If I change the e1 attribute y to 1 or some other positive value this code works, but if the y is 0 or negative it fails. There are no errors but the shape does not appear. If I draw other kind of shapes, same kind of problem occurs. Anyway, rotation values such as 0, 90 and 271 work with y: 0. There is not such a problem with the x value. Why is that? Is it a bug related to Crafty.js?

<script>
        Crafty.init(480,680, document.getElementById('test'));

        Crafty.c("myComponent", {
            init: function () {
                this.requires("2D, Canvas");
                this.bind("Draw", this._draw_me);
                this.ready = true;
            },
            _draw_me: function (e) {
                var ctx = e.ctx;

                ctx.beginPath();
                ctx.moveTo(e.pos._x, e.pos._y);
                ctx.lineTo(e.pos._x + e.pos._w, e.pos._y);
                ctx.lineTo(e.pos._x + e.pos._w/2, e.pos._y + e.pos._h);
                ctx.lineTo(e.pos._x, e.pos._y);

                ctx.fillStyle = "blue";
                ctx.fill();
            }
        });

        var e1 = Crafty.e("myComponent")
            .attr({x: 100, y: 0, w: 60, h: 60, rotation:180})
            .origin("center");
</script>

Answer 1

Set w and h before setting origin. Set the rotation origin before setting the rotation.
This should be clearly documented in the API documentation, I went ahead and opened an issue for that on Crafty's issue tracker.

If you set the origin after the rotation, things get messed up somehow, and the _draw_me function never gets called, as Crafty thinks the triangle sits outside the viewport (camera) and does not need to be drawn. (Observe what happens when you set Crafty.viewport.y = 100 - the triangle appears)

The following snippet works for me. The code sets w and h, origin & rotation, in that order.

Crafty.init();

Crafty.c("myComponent", {
    init: function () {
        this.requires("2D, Canvas");
        this.bind("Draw", this._draw_me);
        this.ready = true;
    },
    _draw_me: function (e) {
        var ctx = e.ctx;

        ctx.beginPath();
        ctx.moveTo(e.pos._x, e.pos._y);
        ctx.lineTo(e.pos._x + e.pos._w, e.pos._y);
        ctx.lineTo(e.pos._x + e.pos._w/2, e.pos._y + e.pos._h);
        ctx.lineTo(e.pos._x, e.pos._y);

        ctx.fillStyle = "blue";
        ctx.fill();
    }
});

var e1 = Crafty.e("myComponent")
    .attr({w: 60, h: 60})
    .origin("center")
    .attr({x: 100, y: 0, rotation: 180});

<script src="https://github.com/craftyjs/Crafty/releases/download/0.7.1/crafty-min.js"></script>