[API] Add bisector method

qgis · Nov 27, 2020 · 7a7d4c8 · 7a7d4c8
1 parent ce916ea
commit 7a7d4c8
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diff --git a/src/core/geometry/qgsgeometryutils.cpp b/src/core/geometry/qgsgeometryutils.cpp
@@ -1717,3 +1717,21 @@ bool QgsGeometryUtils::setZValueFromPoints( const QgsPointSequence &points, QgsP
 
   return rc;
 }
+
+bool QgsGeometryUtils::bisector( double aX, double aY, double bX, double bY, double cX, double cY,
+                                 double &pointX SIP_OUT, double &pointY SIP_OUT )
+{
+  const QgsPoint pA = QgsPoint( aX, aY );
+  const QgsPoint pB = QgsPoint( bX, bY );
+  const QgsPoint pC = QgsPoint( cX, cY );
+  const double angle = ( pA.azimuth( pB ) + pA.azimuth( pC ) ) / 2.0;
+
+  QgsPoint pOut;
+  bool intersection = false;
+  QgsGeometryUtils::segmentIntersection( pB, pC, pA, pA.project( 1.0, angle ), pOut, intersection );
+
+  pointX = pOut.x();
+  pointY = pOut.y();
+
+  return intersection;
+}
diff --git a/src/core/geometry/qgsgeometryutils.h b/src/core/geometry/qgsgeometryutils.h
@@ -727,6 +727,25 @@ class CORE_EXPORT QgsGeometryUtils
      */
     static bool setZValueFromPoints( const QgsPointSequence &points, QgsPoint &point );
 
+    /**
+     * Returns the point (\a pointX, \a pointY) forming the bisector from point (\a aX, \a aY) to the segment (\a bX, \a bY) (\a cX, \a cY).
+     * The bisector segment of ABC is (A-point)
+     *
+     * \param aX x-coordinate of first vertex in triangle
+     * \param aY y-coordinate of first vertex in triangle
+     * \param bX x-coordinate of second vertex in triangle
+     * \param bY y-coordinate of second vertex in triangle
+     * \param cX x-coordinate of third vertex in triangle
+     * \param cY y-coordinate of third vertex in triangle
+     * \param pointX x-coordinate of generated point
+     * \param pointY y-coordinate of generated point
+     * \returns TRUE if the bisector exists (A B and C are not collinear)
+     *
+     * \since QGIS 3.16
+     */
+    static bool bisector( double aX, double aY, double bX, double bY, double cX, double cY,
+                          double &pointX SIP_OUT, double &pointY SIP_OUT ) SIP_HOLDGIL;
+
     //! \note not available in Python bindings
     enum ComponentType SIP_SKIP
     {