More tweaks to leftOf logic

nyalldawson · nyalldawson · commit b8a62f4f4d20 · 2017-11-29T14:29:35.000+10:00
diff --git a/src/core/geometry/qgslinestring.cpp b/src/core/geometry/qgslinestring.cpp
@@ -943,7 +943,7 @@ double QgsLineString::closestSegment( const QgsPoint &pt, QgsPoint &segmentPt,
       // where we can perform the check
       if ( left != 0 )
       {
-        if ( qgsDoubleNear( testDist, leftOfDist ) && ( left < 0 ) != prevLeftOf )
+        if ( qgsDoubleNear( testDist, leftOfDist ) && left != prevLeftOf && prevLeftOf != 0 )
         {
           // we have two possible segments each with equal distance to point, but they disagree
           // on whether or not the point is to the left of them.
@@ -964,6 +964,7 @@ double QgsLineString::closestSegment( const QgsPoint &pt, QgsPoint &segmentPt,
       {
         *leftOf = left;
         leftOfDist = testDist;
+        prevLeftOf = 0;
       }
     }
   }

Original file line number	Diff line number	Diff line change
`@@ -943,7 +943,7 @@ double QgsLineString::closestSegment( const QgsPoint &pt, QgsPoint &segmentPt,`
`943`	`943`	`// where we can perform the check`
`944`	`944`	`if ( left != 0 )`
`945`	`945`	`{`
`946`		`- if ( qgsDoubleNear( testDist, leftOfDist ) && ( left < 0 ) != prevLeftOf )`
	`946`	`+ if ( qgsDoubleNear( testDist, leftOfDist ) && left != prevLeftOf && prevLeftOf != 0 )`
`947`	`947`	`{`
`948`	`948`	`// we have two possible segments each with equal distance to point, but they disagree`
`949`	`949`	`// on whether or not the point is to the left of them.`
`@@ -964,6 +964,7 @@ double QgsLineString::closestSegment( const QgsPoint &pt, QgsPoint &segmentPt,`
`964`	`964`	`{`
`965`	`965`	`*leftOf = left;`
`966`	`966`	`leftOfDist = testDist;`
	`967`	`+ prevLeftOf = 0;`
`967`	`968`	`}`
`968`	`969`	`}`
`969`	`970`	`}`