loading saved track layouts

track.ts

@@ -90,6 +90,16 @@ export class Track extends PathSegment {
         e.drawDot();
       }
   }
+
+  setNext(t: Track) {
+    this.next = t;
+    this.next.points[0] = this.points[3];
+  }
+
+  setPrev(t: Track) {
+    this.prev = t;
+    this.prev.points[3] = this.points[0];
+  }
 }
 
 export class Spline<T extends PathSegment = PathSegment> {
@@ -99,7 +109,7 @@ export class Spline<T extends PathSegment = PathSegment> {
   evenPoints: Vector[];
   constructor(segs: T[]) {
     this.segments = segs;
-    this.evenPoints = this.calculateEvenlySpacedPoints(3);
+    this.evenPoints = this.calculateEvenlySpacedPoints(1);
   }
 
   setContext(ctx: CanvasRenderingContext2D) {
@@ -116,39 +126,40 @@ export class Spline<T extends PathSegment = PathSegment> {
   }
 
   calculateEvenlySpacedPoints(spacing: number, resolution = 1) {
-    return this.segments.flatMap(s => s.calculateEvenlySpacedPoints(spacing, resolution));
-  //   const points: Vector[] = []
+    // return this.segments.flatMap(s => s.calculateEvenlySpacedPoints(spacing, resolution));
+    const points: Vector[] = []
 
-  //   points.push(this.segments[0].points[0]);
-  //   let prev = points[0];
-  //   let distSinceLastEvenPoint = 0
-  //   for (const seg of this.segments) {
+    points.push(this.segments[0].points[0]);
+    let prev = points[0];
+    let distSinceLastEvenPoint = 0
+    for (const seg of this.segments) {
 
-  //     let t = 0;
+      let t = 0;
 
-  //     const div = Math.ceil(seg.length * resolution * 10);
-  //     while (t < 1) {
-  //       t += 1 / div;
-  //       const point = seg.getPointAtT(t);
-  //       distSinceLastEvenPoint += prev.dist(point);
+      const div = Math.ceil(seg.length * resolution * 10);
+      while (t < 1) {
+        t += 1 / div;
+        const point = seg.getPointAtT(t);
+        distSinceLastEvenPoint += prev.dist(point);
 
 
-  //       if (distSinceLastEvenPoint >= spacing) {
-  //         const overshoot = distSinceLastEvenPoint - spacing;
-  //         const evenPoint = Vector.add(point, Vector.sub(point, prev).normalize().mult(overshoot))
-  //         distSinceLastEvenPoint = overshoot;
-  //         points.push(evenPoint);
-  //         prev = evenPoint;
-  //       }
+        if (distSinceLastEvenPoint >= spacing) {
+          const overshoot = distSinceLastEvenPoint - spacing;
+          const evenPoint = Vector.add(point, Vector.sub(point, prev).normalize().mult(overshoot))
+          distSinceLastEvenPoint = overshoot;
+          points.push(evenPoint);
+          prev = evenPoint;
+        }
 
-  //       prev = point
-  //     }
-  //   }
+        prev = point
+      }
+    }
 
-  //   return points;
+    return points;
   }
 
   followEvenPoints(t: number) {
+    if (t < 0) t+= this.evenPoints.length
     const i = Math.floor(t);
     const a = this.evenPoints[i]
     const b = this.evenPoints[(i + 1) % this.evenPoints.length]
@@ -192,3 +203,20 @@ export const generateSquareTrack = () => {
 
   return new Spline<Track>([first, second, third, fourth, fifth, sixth, seventh, eighth]);
 }
+
+export const loadFromJson = () => {
+  const json = JSON.parse(localStorage.getItem('railPath') || '');
+  if (!json) return generateSquareTrack();
+  const segments: Track[] = [];
+
+  for (const {points} of json.segments) {
+    segments.push(new Track(points.map((p:{x:number,y:number}) => new Vector(p.x, p.y))));
+  }
+
+  for (const [i,s] of segments.entries()) {
+    s.setNext(segments[(i+1)%segments.length])
+    s.setPrev(segments.at(i-1)!)
+  }
+
+  return new Spline<Track>(segments);
+}