class AngleStick {
/**
*
* @param {Point} a
* @param {Point} b
* @param {Point} c
* @param {number} stiffness
*/
constructor(a, b, c, stiffness) {
this.a = a;
this.b = b;
this.c = c;
this.angle = this.b.pos.angle2(this.a.pos, this.c.pos);
this.stiffness = stiffness;
}
/**
*
*/
update() {
var angle = this.b.pos.angle2(this.a.pos, this.c.pos);
// get the angle difference
var diff = angle - this.angle;
if (diff <= -Math.PI)
diff += 2 * Math.PI;
else if (diff >= Math.PI)
diff -= 2 * Math.PI;
diff *= 0.1 * this.stiffness;
this.a.pos = this.a.pos.rotateBy(this.b.pos, diff);
this.c.pos = this.c.pos.rotateBy(this.b.pos, -diff);
this.b.pos = this.b.pos.rotateBy(this.a.pos, diff);
this.b.pos = this.b.pos.rotateBy(this.c.pos, -diff);
}
/**
*
* @param {CanvasRenderingContext2D} ctx
*/
render(ctx) {
ctx.beginPath();
ctx.moveTo(this.a.pos.x, this.a.pos.y);
ctx.lineTo(this.b.pos.x, this.b.pos.y);
ctx.lineTo(this.c.pos.x, this.c.pos.y);
var tmp = ctx.lineWidth;
ctx.lineWidth = 5;
ctx.strokeStyle = "rgba(0, 0, 255, 0.5)";
ctx.stroke();
ctx.lineWidth = tmp;
}
}
export default AngleStick;Source