code comments

docs/chapters/extended/extended.js

@@ -8,20 +8,27 @@ setup() {
 
 draw() {
     clear();
-    curve.drawCurve();
-    curve.drawSkeleton();
 
-    let step=0.05, min=-10, max=10;
+    // let's draw the curve from -10 to 10, instead of 0 to 1
+    setStroke(`skyblue`);
+    let min=-10, max=10, step=0.05;
+
+    // calculate the very first point
     let pt = curve.get(min - step), pn;
 
-    setStroke(`skyblue`);
 
-    for (let t=min; t<=step; t+=step) {
+    // then draw the section from -10 to 0
+    for (let t=min; t<step; t+=step) {
       pn = curve.get(t);
       line(pt.x, pt.y, pn.x, pn.y);
       pt = pn;
     }
 
+    // then the regular curve, from 0 to 1
+    curve.drawSkeleton();
+    curve.drawCurve();
+
+    // then draw the section from 1 to 10
     pt = curve.get(1);
     for (let t=1+step; t<=max; t+=step) {
       pn = curve.get(t);
@@ -29,5 +36,7 @@ draw() {
       pt = pn;
     }
 
+    // and just to make sure they show on top,
+    // draw the curve's control points last.
     curve.drawPoints();
 }