From e93a497cd86587e92102af00996ab356bf49872a Mon Sep 17 00:00:00 2001
From: casperlamboo <casperlamboo@gmail.com>
Date: Wed, 8 Nov 2017 22:01:31 +0100
Subject: [PATCH] add curve utils

---
 src/shape/shapeToPoints.js |  1 +
 src/utils/curveUtils.js    | 70 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+)
 create mode 100644 src/utils/curveUtils.js

diff --git a/src/shape/shapeToPoints.js b/src/shape/shapeToPoints.js
index 4e0edca..e2863b0 100644
--- a/src/shape/shapeToPoints.js
+++ b/src/shape/shapeToPoints.js
@@ -7,6 +7,7 @@ import { CLIPPER_PRECISION } from '../constants/d2Constants.js';
 import { MAX_ANGLE } from '../constants/d3Constants.js';
 import { SHAPE_CACHE_LIMIT } from '../constants/general.js';
 import { createText } from '../utils/textUtils.js';
+import { segmentBezierPath } from '../utils/curveUtils.js';
 
 const HEART_BEZIER_PATH = [
   new Vector(0.0, -0.5),
diff --git a/src/utils/curveUtils.js b/src/utils/curveUtils.js
new file mode 100644
index 0000000..47bebe1
--- /dev/null
+++ b/src/utils/curveUtils.js
@@ -0,0 +1,70 @@
+import fitCurve from 'fit-curve';
+import Bezier from 'bezier-js';
+import { Vector } from 'cal';
+
+const DEFAULT_CURVE_ERROR = 3.0;
+const DEFAULT_DISTANCE_THRESHOLD = 1.0;
+
+export function fitPath(path, curveError = DEFAULT_CURVE_ERROR) {
+  if (!path || path.length === 0) throw new Error('Path contains no points in fitPath');
+  const first = path[0].clone(); // store first point so it can be used in reduce function
+  path = path.map(({ x, y }) => [x, y]); // convert path to [...[x, y]] format
+  return fitCurve(path, curveError)
+    .reduce((bezierPath, [ // convert to [...Vector] format. n+0 is path point, n+1 and n+2 are control points
+      start,
+      [controlPoint1X, controlPoint1Y],
+      [controlPoint2X, controlPoint2Y],
+      [endX, endY]
+    ]) => {
+      bezierPath.push(
+        new Vector(controlPoint1X, controlPoint1Y),
+        new Vector(controlPoint2X, controlPoint2Y),
+        new Vector(endX, endY)
+      );
+
+      return bezierPath;
+    }, [first]);  // always add first point
+}
+
+export function segmentBezierPath(bezierPath, distanceThreshold = DEFAULT_DISTANCE_THRESHOLD) {
+  const path = [];
+  for (let i = 0; i < bezierPath.length - 3; i += 3) {
+    const bezierCurve = new Bezier(
+      bezierPath[i].x, bezierPath[i].y,
+      bezierPath[i + 1].x, bezierPath[i + 1].y,
+      bezierPath[i + 2].x, bezierPath[i + 2].y,
+      bezierPath[i + 3].x, bezierPath[i + 3].y
+    );
+    path.push(...recursiveBezierSegmenter(distanceThreshold, bezierCurve));
+  }
+  path.push(new Vector().copy(bezierPath[bezierPath.length - 1]));
+  return path;
+}
+
+function recursiveBezierSegmenter(
+  distanceThreshold, bezierCurve,
+  tStart = 0.0, tEnd = 1.0,
+  pStart = new Vector().copy(bezierCurve.get(tStart)), pEnd = new Vector().copy(bezierCurve.get(tEnd))
+) {
+  const tCenter = (tStart + tEnd) * 0.5;
+  const pCenter = new Vector().copy(bezierCurve.get(tCenter));
+
+  const distance = Math.abs(pEnd.subtract(pStart).normal().normalize().dot(pCenter.subtract(pStart)));
+
+  if (distance > distanceThreshold) {
+    const segmentStart = recursiveBezierSegmenter(
+      distanceThreshold, bezierCurve,
+      tStart, tCenter,
+      pStart, pCenter
+    );
+    const segmentEnd = recursiveBezierSegmenter(
+      distanceThreshold, bezierCurve,
+      tCenter, tEnd,
+      pCenter, pEnd
+    );
+
+    return segmentStart.concat(segmentEnd);
+  } else {
+    return [pStart];
+  }
+}