Better error handling for polygon clipping

mhugent · mhugent · commit e9435ebeaa74 · 2011-04-24T20:59:54.000Z
git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@15817 c8812cc2-4d05-0410-92ff-de0c093fc19c
diff --git a/src/core/qgsclipper.h b/src/core/qgsclipper.h
@@ -421,18 +421,12 @@ inline QPointF QgsClipper::intersectRect( const QPointF& pt1,
       break;
   }
 
-  if ( std::abs( r_d ) > SMALL_NUM && std::abs( r_n ) > SMALL_NUM )
-  { // they cross
-    double r = r_n / r_d;
-    return QPointF( x1 + r*( x2 - x1 ), y1 + r*( y2 - y1 ) );
-  }
-  else
+  double r = 0;
+  if ( !doubleNear( r_d, 0.0 ) )
   {
-    // Should never get here, but if we do for some reason, cause a
-    // clunk because something else is wrong if we do.
-    Q_ASSERT( std::abs( r_d ) > SMALL_NUM && std::abs( r_n ) > SMALL_NUM );
-    return QPointF();
+    r = r_n / r_d;
   }
+  return QPointF( x1 + r*( x2 - x1 ), y1 + r*( y2 - y1 ) );
 }
 
 inline void QgsClipper::clipStartTop( double& x0, double& y0, const double& x1, const double& y1, double yMax )

Original file line number	Diff line number	Diff line change
`@@ -421,18 +421,12 @@ inline QPointF QgsClipper::intersectRect( const QPointF& pt1,`
`421`	`421`	`break;`
`422`	`422`	`}`
`423`	`423`
`424`		`- if ( std::abs( r_d ) > SMALL_NUM && std::abs( r_n ) > SMALL_NUM )`
`425`		`- { // they cross`
`426`		`- double r = r_n / r_d;`
`427`		`- return QPointF( x1 + r( x2 - x1 ), y1 + r( y2 - y1 ) );`
`428`		`- }`
`429`		`- else`
	`424`	`+ double r = 0;`
	`425`	`+ if ( !doubleNear( r_d, 0.0 ) )`
`430`	`426`	`{`
`431`		`- // Should never get here, but if we do for some reason, cause a`
`432`		`- // clunk because something else is wrong if we do.`
`433`		`- Q_ASSERT( std::abs( r_d ) > SMALL_NUM && std::abs( r_n ) > SMALL_NUM );`
`434`		`- return QPointF();`
	`427`	`+ r = r_n / r_d;`
`435`	`428`	`}`
	`429`	`+ return QPointF( x1 + r( x2 - x1 ), y1 + r( y2 - y1 ) );`
`436`	`430`	`}`
`437`	`431`
`438`	`432`	`inline void QgsClipper::clipStartTop( double& x0, double& y0, const double& x1, const double& y1, double yMax )`