Fix PathItem#isCrossing() to not return overlaps

Closes paperjs#1409

src/path/PathItem.Boolean.js

@@ -97,6 +97,17 @@ PathItem.inject(new function() {
  return result;
  }
 
+ function filterIntersection(inter) {
+ // TODO: Change isCrossing() to also handle overlaps (hasOverlap())
+ // that are actually involved in a crossing! For this we need proper
+ // overlap range detection / merging first... But as we call
+ // #resolveCrossings() first in boolean operations, removing all
+ // self-touching areas in paths, this works for the known use cases.
+ // The ideal implementation would deal with it in a way outlined in:
+ // https://github.com/paperjs/paper.js/issues/874#issuecomment-168332391
+ return inter.hasOverlap() || inter.isCrossing();
+ }
+
  function traceBoolean(path1, path2, operation, options) {
  // Only support subtract and intersect operations when computing stroke
  // based boolean operations (options.split = true).
@@ -121,8 +132,8 @@ PathItem.inject(new function() {
  _path2.reverse();
  // Split curves at crossings on both paths. Note that for self-
  // intersection, path2 is null and getIntersections() handles it.
- var crossings = divideLocations(
- CurveLocation.expand(_path1.getCrossings(_path2))),
+ var crossings = divideLocations(CurveLocation.expand(
+ _path1.getIntersections(_path2, filterIntersection))),
  paths1 = getPaths(_path1),
  paths2 = _path2 && getPaths(_path2),
  segments = [],
@@ -182,7 +193,7 @@ PathItem.inject(new function() {
  function splitBoolean(path1, path2, operation) {
  var _path1 = preparePath(path1),
  _path2 = preparePath(path2),
- crossings = _path1.getCrossings(_path2),
+ crossings = _path1.getIntersections(_path2, filterIntersection),
  subtract = operation === 'subtract',
  divide = operation === 'divide',
  added = {},

src/path/PathItem.js

@@ -351,14 +351,7 @@ var PathItem = Item.extend(/** @lends PathItem# */{
  */
  getCrossings: function(path) {
  return this.getIntersections(path, function(inter) {
- // TODO: Only return overlaps that are actually crossings! For this
- // we need proper overlap range detection / merging first...
- // But as we call #resolveCrossings() first in boolean operations,
- // removing all self-touching areas in paths, this currently works
- // as it should in the known use cases.
- // The ideal implementation would deal with it in a way outlined in:
- // https://github.com/paperjs/paper.js/issues/874#issuecomment-168332391
- return inter.hasOverlap() || inter.isCrossing();
+ return inter.isCrossing();
  });
  },
 

test/tests/Path_Intersections.js

@@ -380,3 +380,23 @@ test('#1262', function() {
  { point: { x: 567.05562, y: 634.62043 }, time: 1 }
  ]);
 });
+
+test('#1409', function() {
+ var path1 = new Path({
+ segments: [[20, 20], [20, 80], [80, 80], [80, 20]],
+ closed: true
+ });
+ var path2 = new Path({
+ segments: [[80, 20], [80, 80], [140, 80], [140, 20]],
+ closed: true
+ });
+ testIntersections(path1.getCrossings(path2), []);
+
+ var rect1 = new Path.Rectangle(new Point(100, 100), new Size(100, 100));
+ var rect2 = rect1.clone();
+ testIntersections(rect1.getCrossings(rect2), []);
+
+ var circ1 = new Path.Circle(new Point(300,300), 40);
+ var circ2 = circ1.clone();
+ testIntersections(circ1.getCrossings(circ2), []);
+});