figured out how to reuse sketches with data-attribute parameters

docs/chapters/flattening/flatten.js

@@ -0,0 +1,27 @@
+let curve;
+
+setup() {
+  const type = getParameter(`type`, `quadratic`);
+  curve = (type === `quadratic`) ? Bezier.defaultQuadratic(this) : Bezier.defaultCubic(this);
+  setMovable(curve.points);
+  setSlider(`.slide-control`, `steps`, (type === `quadratic`) ? 4 : 8);
+}
+
+draw() {
+  clear();
+
+  curve.drawSkeleton();
+
+  noFill();
+  start();
+  for(let i=0, e=this.steps; i<=e; i++) {
+    let p = curve.get(i/e);
+    vertex(p.x, p.y);
+  }
+  end();
+
+  curve.drawPoints();
+
+  setFill(`black`);
+  text(`Flattened to ${this.steps} segments`, 10, 15);
+}