use better polyline simplification

src/index.html

@@ -7,7 +7,7 @@
     <script src="coloris.js"></script>
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Tauri App</title>
-    <!-- <script type="module" src="/fit-curve.js"></script> -->
+    <script type="module" src="/simplify.js"></script>
     <script type="module" src="/main.js" defer></script>
   </head>
 

src/main.js

@@ -1,6 +1,8 @@
 const { invoke } = window.__TAURI__.core;
 import * as fitCurve from '/fit-curve.js';
 
+let simplifyPolyline = simplify
+
 let greetInputEl;
 let greetMsgEl;
 let rootPane;
@@ -96,27 +98,23 @@ class Shape {
   addCurve(curve) {
     this.curves.push(curve)
   }
-  simplify(mode="smooth") {
+  simplify(mode="corners") {
     // Mode can be corners, smooth or auto
     if (mode=="corners") {
-      let angles;
-      while (this.curves.length > 3) {
-        angles = [2*Math.PI]
-        for (let i=1; i<this.curves.length-1; i++) {
-          let P1 = this.curves[i]
-          let P2 = this.curves[i-1]
-          let P3 = this.curves[i+1]
-          let angle = Math.atan2(P3.y - P1.y, P3.x - P1.x) -
-                  Math.atan2(P2.y - P1.y, P2.x - P1.x);
-          angles[i] = Math.abs(Math.PI - Math.abs(angle))
-        }
-        let smallestAngle = Math.min(...angles)
-        if (smallestAngle < maxSmoothAngle) {
-          this.curves.splice(angles.indexOf(smallestAngle), 1)
-        } else {
-          break;
-        }
+      let points = [{x: this.startx, y: this.starty}]
+      points = points.concat(this.curves)
+      let newpoints = simplifyPolyline(points, 10, false)
+      console.log(points.length)
+      console.log(newpoints.length)
+      this.curves = []
+      let lastpoint = newpoints.shift()
+      let midpoint
+      for (let point of newpoints) {
+        midpoint = {x: (lastpoint.x+point.x)/2, y: (lastpoint.y+point.y)/2}
+        this.curves.push(new Curve(midpoint.x, midpoint.y,midpoint.x,midpoint.y,point.x,point.y))
+        lastpoint = point
       }
+      console.log(this.curves)
     } else if (mode=="smooth") {
       let error = 30;
       let points = [[this.startx, this.starty]]

src/simplify.js

@@ -0,0 +1,123 @@
+/*
+ (c) 2017, Vladimir Agafonkin
+ Simplify.js, a high-performance JS polyline simplification library
+ mourner.github.io/simplify-js
+*/
+
+(function () { 'use strict';
+
+// to suit your point format, run search/replace for '.x' and '.y';
+// for 3D version, see 3d branch (configurability would draw significant performance overhead)
+
+// square distance between 2 points
+function getSqDist(p1, p2) {
+
+    var dx = p1.x - p2.x,
+        dy = p1.y - p2.y;
+
+    return dx * dx + dy * dy;
+}
+
+// square distance from a point to a segment
+function getSqSegDist(p, p1, p2) {
+
+    var x = p1.x,
+        y = p1.y,
+        dx = p2.x - x,
+        dy = p2.y - y;
+
+    if (dx !== 0 || dy !== 0) {
+
+        var t = ((p.x - x) * dx + (p.y - y) * dy) / (dx * dx + dy * dy);
+
+        if (t > 1) {
+            x = p2.x;
+            y = p2.y;
+
+        } else if (t > 0) {
+            x += dx * t;
+            y += dy * t;
+        }
+    }
+
+    dx = p.x - x;
+    dy = p.y - y;
+
+    return dx * dx + dy * dy;
+}
+// rest of the code doesn't care about point format
+
+// basic distance-based simplification
+function simplifyRadialDist(points, sqTolerance) {
+
+    var prevPoint = points[0],
+        newPoints = [prevPoint],
+        point;
+
+    for (var i = 1, len = points.length; i < len; i++) {
+        point = points[i];
+
+        if (getSqDist(point, prevPoint) > sqTolerance) {
+            newPoints.push(point);
+            prevPoint = point;
+        }
+    }
+
+    if (prevPoint !== point) newPoints.push(point);
+
+    return newPoints;
+}
+
+function simplifyDPStep(points, first, last, sqTolerance, simplified) {
+    var maxSqDist = sqTolerance,
+        index;
+
+    for (var i = first + 1; i < last; i++) {
+        var sqDist = getSqSegDist(points[i], points[first], points[last]);
+
+        if (sqDist > maxSqDist) {
+            index = i;
+            maxSqDist = sqDist;
+        }
+    }
+
+    if (maxSqDist > sqTolerance) {
+        if (index - first > 1) simplifyDPStep(points, first, index, sqTolerance, simplified);
+        simplified.push(points[index]);
+        if (last - index > 1) simplifyDPStep(points, index, last, sqTolerance, simplified);
+    }
+}
+
+// simplification using Ramer-Douglas-Peucker algorithm
+function simplifyDouglasPeucker(points, sqTolerance) {
+    var last = points.length - 1;
+
+    var simplified = [points[0]];
+    simplifyDPStep(points, 0, last, sqTolerance, simplified);
+    simplified.push(points[last]);
+
+    return simplified;
+}
+
+// both algorithms combined for awesome performance
+function simplify(points, tolerance, highestQuality) {
+
+    if (points.length <= 2) return points;
+
+    var sqTolerance = tolerance !== undefined ? tolerance * tolerance : 1;
+
+    points = highestQuality ? points : simplifyRadialDist(points, sqTolerance);
+    points = simplifyDouglasPeucker(points, sqTolerance);
+
+    return points;
+}
+
+// export as AMD module / Node module / browser or worker variable
+if (typeof define === 'function' && define.amd) define(function() { return simplify; });
+else if (typeof module !== 'undefined') {
+    module.exports = simplify;
+    module.exports.default = simplify;
+} else if (typeof self !== 'undefined') self.simplify = simplify;
+else window.simplify = simplify;
+
+})();