Improve line intersection checks

src/Line.php

@@ -6,7 +6,6 @@
 
 use Location\Bearing\BearingInterface;
 use Location\Distance\DistanceInterface;
-use Location\Intersection\Intersection;
 use Location\Utility\Cartesian;
 use RuntimeException;
 
@@ -62,7 +61,7 @@ public function getSegments(): array
      * Calculates the length of the line (distance between the two
      * coordinates in meters).
      *
-     * @param DistanceInterface $calculator instance of distance calculation class
+     * @param  DistanceInterface  $calculator  instance of distance calculation class
      */
     public function getLength(DistanceInterface $calculator): float
     {
@@ -117,7 +116,7 @@ public function getMidpoint(): Coordinate
      * @see http://www.movable-type.co.uk/scripts/latlong.html#intermediate-point
      * @see http://www.edwilliams.org/avform.htm#Intermediate
      *
-     * @param float $fraction 0.0 ... 1.0 (smaller or larger values work too)
+     * @param  float  $fraction  0.0 ... 1.0 (smaller or larger values work too)
      *
      * @throws RuntimeException
      */
@@ -133,7 +132,7 @@ public function getIntermediatePoint(float $fraction): Coordinate
         if ($lat1 + $lat2 == 0.0 && abs($lng1 - $lng2) == M_PI) {
             throw new RuntimeException(
                 'Start and end points are antipodes, route is therefore undefined.',
-                5382449689
+                5382449689,
             );
         }
 
@@ -153,6 +152,71 @@ public function getIntermediatePoint(float $fraction): Coordinate
         return new Coordinate(rad2deg($lat), rad2deg($lng));
     }
 
+    /**
+     * Two lines intersect if:
+     *
+     * 1. The points of the given line are oriented into opposite directions
+     * 2. The points of this line are oriented into opposite directions
+     * 3. The points are collinear and the line segments are overlapping
+     */
+    public function intersectsLine(Line $line): bool
+    {
+        $orientation = [];
+        $orientation[11] = $this->getOrientation($line->point1);
+        $orientation[12] = $this->getOrientation($line->point2);
+        $orientation[21] = $line->getOrientation($this->point1);
+        $orientation[22] = $line->getOrientation($this->point2);
+
+        // the lines cross
+        if (
+            $orientation[11] !== $orientation[12]
+            && $orientation[21] !== $orientation[22]
+        ) {
+            return true;
+        }
+
+        // the lines are collinear or touch
+        if (!in_array(self::ORIENTATION_COLLINEAR, $orientation, true)) {
+            return false;
+        }
+
+        if (
+            $orientation[11] === self::ORIENTATION_COLLINEAR && $this->isPointInBounds(
+                $line->point1,
+                $this->getBounds(),
+            )
+        ) {
+            return true;
+        }
+        if (
+            $orientation[12] === self::ORIENTATION_COLLINEAR && $this->isPointInBounds(
+                $line->point2,
+                $this->getBounds(),
+            )
+        ) {
+            return true;
+        }
+        if (
+            $orientation[21] === self::ORIENTATION_COLLINEAR && $this->isPointInBounds(
+                $this->point1,
+                $line->getBounds(),
+            )
+        ) {
+            return true;
+        }
+        if (
+            $orientation[22] === self::ORIENTATION_COLLINEAR && $this->isPointInBounds(
+                $this->point2,
+                $line->getBounds(),
+            )
+        ) {
+            return true;
+        }
+
+        // the lines do not overlap
+        return false;
+    }
+
     /**
      * Compares the location of a given coordinate to this line returning
      * its orientation as:
@@ -164,9 +228,9 @@ public function getIntermediatePoint(float $fraction): Coordinate
     public function getOrientation(Coordinate $coordinate): int
     {
         $crossproduct1 = ($this->point2->getLat() - $this->point1->getLat())
-                         * ($coordinate->getLng() - $this->point2->getLng());
-        $crossproduct2 = ($this->point2->getLng() - $this->point1->getLng())
-                         * ($coordinate->getLat() - $this->point2->getLat());
+            * $this->getDeltaLng($this->point2, $coordinate);
+        $crossproduct2 = $this->getDeltaLng($this->point1, $this->point2)
+            * ($coordinate->getLat() - $this->point2->getLat());
         $delta = $crossproduct1 - $crossproduct2;
 
         if ($delta > 0) {
@@ -180,38 +244,26 @@ public function getOrientation(Coordinate $coordinate): int
         return self::ORIENTATION_COLLINEAR;
     }
 
-    /**
-     * Two lines intersect if:
-     *
-     * 1. the points of the given line are oriented into opposite directions
-     * 2. the points of this line are oriented into opposite directions
-     * 3. the points are collinear and the two line segments are overlapping
-     */
-    public function intersectsLine(Line $line): bool
+    private function getDeltaLng(Coordinate $point1, Coordinate $point2): float
     {
-        $orientation = [];
-        $orientation[11] = $this->getOrientation($line->point1);
-        $orientation[12] = $this->getOrientation($line->point2);
-        $orientation[21] = $line->getOrientation($this->point1);
-        $orientation[22] = $line->getOrientation($this->point2);
+        $deltaLng = $point2->getLng() - $point1->getLng();
 
-        // the lines cross
-        if (
-            $orientation[11] !== $orientation[12]
-            && $orientation[21] !== $orientation[22]
-        ) {
-            return true;
+        if ($deltaLng > 180) {
+            return $deltaLng - 360;
         }
 
-        // the lines are collinear or touch
-        if (
-            in_array(self::ORIENTATION_COLLINEAR, $orientation, true)
-            && (new Intersection())->intersects($this, $line, false)
-        ) {
-            return true;
+        if ($deltaLng < -180) {
+            return $deltaLng + 360;
         }
 
-        // the lines do not overlap
-        return false;
+        return $deltaLng;
+    }
+
+    private function isPointInBounds(Coordinate $point, Bounds $bounds): bool
+    {
+        return $point->getLat() >= $bounds->getSouth()
+            && $point->getLat() <= $bounds->getNorth()
+            && $point->getLng() >= $bounds->getWest()
+            && $point->getLng() <= $bounds->getEast();
     }
 }

tests/Location/LineIntersectionTest.php

@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Location;
+
+use PHPUnit\Framework\TestCase;
+
+class LineIntersectionTest extends TestCase
+{
+    public function testIntersectsLineSimpleCrossing(): void
+    {
+        $line1 = new Line(new Coordinate(0, 0), new Coordinate(10, 10));
+        $line2 = new Line(new Coordinate(0, 10), new Coordinate(10, 0));
+
+        $this->assertTrue($line1->intersectsLine($line2));
+    }
+
+    public function testIntersectsLineParallelDisjoint(): void
+    {
+        $line1 = new Line(new Coordinate(0, 0), new Coordinate(10, 0));
+        $line2 = new Line(new Coordinate(0, 1), new Coordinate(10, 1));
+
+        $this->assertFalse($line1->intersectsLine($line2));
+    }
+
+    public function testIntersectsLineCollinearOverlapping(): void
+    {
+        $line1 = new Line(new Coordinate(0, 0), new Coordinate(10, 0));
+        $line2 = new Line(new Coordinate(5, 0), new Coordinate(15, 0));
+
+        $this->assertTrue($line1->intersectsLine($line2));
+    }
+
+    public function testIntersectsLineCollinearDisjoint(): void
+    {
+        $line1 = new Line(new Coordinate(0, 0), new Coordinate(10, 0));
+        $line2 = new Line(new Coordinate(12, 0), new Coordinate(15, 0));
+
+        $this->assertFalse($line1->intersectsLine($line2));
+    }
+
+    public function testIntersectsLineSharingEndpoint(): void
+    {
+        $line1 = new Line(new Coordinate(0, 0), new Coordinate(10, 0));
+        $line2 = new Line(new Coordinate(10, 0), new Coordinate(10, 10));
+
+        $this->assertTrue($line1->intersectsLine($line2));
+    }
+
+    public function testIntersectsLineTJunction(): void
+    {
+        $line1 = new Line(new Coordinate(0, 0), new Coordinate(10, 0));
+        $line2 = new Line(new Coordinate(5, 0), new Coordinate(5, 5));
+
+        $this->assertTrue($line1->intersectsLine($line2));
+    }
+
+    public function testIntersectsLineDatelineCrossing(): void
+    {
+        $line1 = new Line(new Coordinate(0, 179), new Coordinate(0, -179));
+        $line2 = new Line(new Coordinate(1, 180), new Coordinate(-1, 180));
+
+        $this->assertTrue($line1->intersectsLine($line2));
+    }
+}

tests/Regression/Github/96/Issue96Test.php

@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Location;
+
+use PHPUnit\Framework\TestCase;
+
+class Issue96Test extends TestCase
+{
+    public function testFailingForIssue96(): void
+    {
+        $line1 = new Line(
+            new Coordinate(0.0, 0.0),
+            new Coordinate(0.0, 2.0),
+        );
+        $line2 = new Line(
+            new Coordinate(2.0, 2.0),
+            new Coordinate(0.0, 10.0),
+        );
+
+        $this->assertFalse($line1->intersectsLine($line2));
+    }
+
+    public function testPassingForIssue96(): void
+    {
+        $line1 = new Line(
+            new Coordinate(0.0, 0.0),
+            new Coordinate(0.0, 1.999999),
+        );
+        $line2 = new Line(
+            new Coordinate(2.0, 2.0),
+            new Coordinate(0.0, 10.0),
+        );
+
+        $this->assertFalse($line1->intersectsLine($line2));
+    }
+}