Optimize Item#intersects() by only checking to see if there are at least one intersection.

src/item/Item.js

@@ -1684,11 +1684,10 @@ var Item = Base.extend(Emitter, /** @lends Item# */{
     intersects: function(item, _matrix) {
         if (!(item instanceof Item))
             return false;
-        // TODO: Optimize getIntersections(): We don't need all intersections
-        // when we're just curious about whether they intersect or not. Pass on
-        // an argument that let's it bail out after the first intersection.
-        return this._asPathItem().getIntersections(item._asPathItem(),
-                _matrix || item._matrix).length > 0;
+        // Tell _getIntersections to return as soon as some intersections are
+        // found, because all we care for here is there are some or none:
+        return this._asPathItem()._getIntersections(item._asPathItem(),
+                _matrix || item._matrix, [], true).length > 0;
     },
 
     /**

src/path/PathItem.Boolean.js

@@ -77,7 +77,8 @@ PathItem.inject(new function() {
             _path2.reverse();
         // Split curves at intersections on both paths. Note that for self
         // intersection, _path2 will be null and getIntersections() handles it.
-        splitPath(_path1.getIntersections(_path2, null, true));
+        splitPath(Curve.filterIntersections(
+                _path1._getIntersections(_path2, null, []), true));
 
         var chain = [],
             segments = [],
@@ -538,7 +539,7 @@ PathItem.inject(new function() {
                             // the correct contour to traverse next.
                             w3 = t1.cross(t3),
                             w4 = t1.cross(t4);
-                        if (Math.abs(w3 * w4) > Numerical.EPSILON) {
+                        if (Math.abs(w3 * w4) > /*#=*/Numerical.EPSILON) {
                             // Do not attempt to switch contours if we aren't
                             // sure that there is a possible candidate.
                             var curve = w3 < w4 ? c3 : c4,
@@ -603,7 +604,8 @@ PathItem.inject(new function() {
                         ? startInterSeg : seg)._handleIn);
             } else {
                 path.lastSegment._handleOut.set(0, 0);
-                console.error('Boolean operation results in open path!');
+                console.error('Boolean operation results in open path, length =',
+                    path._segments.length);
             }
             path.setClosed(true);
             // Add the path to the result, while avoiding stray segments and

src/path/PathItem.js

@@ -59,19 +59,21 @@ var PathItem = Item.extend(/** @lends PathItem# */{
      *     }
      * }
      */
-    getIntersections: function(path, _matrix, _expand) {
+    getIntersections: function(path, _matrix) {
         // NOTE: For self-intersection, path is null. This means you can also
         // just call path.getIntersections() without an argument to get self
         // intersections.
         // NOTE: The hidden argument _matrix is used internally to override the
         // passed path's transformation matrix.
-        if (this === path)
-            path = null;
-        var locations = [],
-            curves1 = this.getCurves(),
+        return Curve.filterIntersections(this._getIntersections(
+                this !== path ? path : null, _matrix, []));
+    },
+
+    _getIntersections: function(path, matrix, locations, returnFirst) {
+        var curves1 = this.getCurves(),
             curves2 = path ? path.getCurves() : curves1,
             matrix1 = this._matrix.orNullIfIdentity(),
-            matrix2 = path ? (_matrix || path._matrix).orNullIfIdentity()
+            matrix2 = path ? (matrix || path._matrix).orNullIfIdentity()
                 : matrix1,
             length1 = curves1.length,
             length2 = path ? curves2.length : length1,
@@ -120,6 +122,10 @@ var PathItem = Item.extend(/** @lends PathItem# */{
             // Check for intersections with other curves. For self intersection,
             // we can start at i + 1 instead of 0
             for (var j = path ? 0 : i + 1; j < length2; j++) {
+                // There might be already one location from the above
+                // self-intersection check:
+                if (returnFirst && locations.length)
+                    break;
                 Curve.getIntersections(
                     values1, values2[j], curve1, curves2[j], locations,
                     // Avoid end point intersections on consecutive curves when
@@ -132,7 +138,7 @@ var PathItem = Item.extend(/** @lends PathItem# */{
                 );
             }
         }
-        return Curve.filterIntersections(locations, _expand);
+        return locations;
     },
 
     _asPathItem: function() {