Optimise method

Avoid duplicate calculations (cherry picked from commit e227e93)
qgis · Jun 10, 2019 · 5635c4f · 5635c4f
1 parent f298a85
commit 5635c4f
Showing 1 changed file with 8 additions and 6 deletions.
diff --git a/src/core/geometry/qgsgeometryutils.cpp b/src/core/geometry/qgsgeometryutils.cpp
@@ -327,10 +327,10 @@ bool QgsGeometryUtils::lineCircleIntersection( const QgsPointXY &center, const d
   const double dx = x2 - x1;
   const double dy = y2 - y1;
 
-  const double dr = std::sqrt( std::pow( dx, 2 ) + std::pow( dy, 2 ) );
+  const double dr2 = std::pow( dx, 2 ) + std::pow( dy, 2 );
   const double d = x1 * y2 - x2 * y1;
 
-  const double disc = std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 );
+  const double disc = std::pow( radius, 2 ) * dr2 - std::pow( d, 2 );
 
   if ( disc < 0 )
   {
@@ -342,12 +342,14 @@ bool QgsGeometryUtils::lineCircleIntersection( const QgsPointXY &center, const d
     // two solutions
     const int sgnDy = dy < 0 ? -1 : 1;
 
-    const double ax = center.x() + ( d * dy + sgnDy * dx * std::sqrt( std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 ) ) ) / ( std::pow( dr, 2 ) );
-    const double ay = center.y() + ( -d * dx + std::fabs( dy ) * std::sqrt( std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 ) ) ) / ( std::pow( dr, 2 ) );
+    const double sqrDisc = std::sqrt( disc );
+
+    const double ax = center.x() + ( d * dy + sgnDy * dx * sqrDisc ) / dr2;
+    const double ay = center.y() + ( -d * dx + std::fabs( dy ) * sqrDisc ) / dr2;
     const QgsPointXY p1( ax, ay );
 
-    const double bx = center.x() + ( d * dy - sgnDy * dx * std::sqrt( std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 ) ) ) / ( std::pow( dr, 2 ) );
-    const double by = center.y() + ( -d * dx - std::fabs( dy ) * std::sqrt( std::pow( radius, 2 ) * std::pow( dr, 2 ) - std::pow( d, 2 ) ) ) / ( std::pow( dr, 2 ) );
+    const double bx = center.x() + ( d * dy - sgnDy * dx * sqrDisc ) / dr2;
+    const double by = center.y() + ( -d * dx - std::fabs( dy ) * sqrDisc ) / dr2;
     const QgsPointXY p2( bx, by );
 
     // snap to nearest intersection