Add azimuth function

qgis · Jan 13, 2016 · b7170b8 · b7170b8
1 parent f8de083
commit b7170b8
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diff --git a/resources/function_help/json/azimuth b/resources/function_help/json/azimuth
@@ -0,0 +1,13 @@
+{
+  "name": "azimuth",
+  "type": "function",
+  "description": "Returns the north-based azimuth as the angle in radians measured clockwise from the vertical on pointA to pointB.",
+  "arguments": [
+    {"arg":"pointA","description":"point geometry"},
+    {"arg":"pointB","description":"point geometry"}
+  ],
+  "examples": [
+	{ "expression":"degrees( azimuth( make_point(25, 45), make_point(75, 100) ) )", "returns":"42.273689"},
+	{ "expression":"degrees( azimuth( make_point(75, 100), make_point(25,45) ) )", "returns":"222.273689"}
+  ]
+}
diff --git a/src/core/qgsexpression.cpp b/src/core/qgsexpression.cpp
@@ -2082,6 +2082,77 @@ static QVariant fcnGeomToWKT( const QVariantList& values, const QgsExpressionCon
   return QVariant( wkt );
 }
 
+static QVariant fcnAzimuth( const QVariantList& values, const QgsExpressionContext *, QgsExpression* parent )
+{
+  if ( values.length() != 2 )
+  {
+    parent->setEvalErrorString( QObject::tr( "Function `azimuth` requires exactly two parameters. %1 given." ).arg( values.length() ) );
+    return QVariant();
+  }
+
+  QgsGeometry fGeom1 = getGeometry( values.at( 0 ), parent );
+  QgsGeometry fGeom2 = getGeometry( values.at( 1 ), parent );
+
+  const QgsPointV2* pt1 = dynamic_cast<const QgsPointV2*>( fGeom1.geometry() );
+  const QgsPointV2* pt2 = dynamic_cast<const QgsPointV2*>( fGeom2.geometry() );
+
+  if ( !pt1 || !pt2 )
+  {
+    parent->setEvalErrorString( QObject::tr( "Function `azimuth` requires two points as arguments." ) );
+    return QVariant();
+  }
+
+  // Code from postgis
+  if ( pt1->x() == pt2->x() )
+  {
+    if ( pt1->y() < pt2->y() )
+      return 0.0;
+    else if ( pt1->y() > pt2->y() )
+      return M_PI;
+    else return 0;
+    return 1;
+  }
+
+  if ( pt1->y() == pt2->y() )
+  {
+    if ( pt1->x() < pt2->x() )
+      return M_PI / 2;
+    else if ( pt1->x() > pt2->x() )
+      return M_PI + ( M_PI / 2 );
+    else return 0;
+    return 1;
+  }
+
+  if ( pt1->x() < pt2->x() )
+  {
+    if ( pt1->y() < pt2->y() )
+    {
+      return atan( fabs( pt1->x() - pt2->x() ) / fabs( pt1->y() - pt2->y() ) );
+    }
+    else /* ( pt1->y() > pt2->y() )  - equality case handled above */
+    {
+      return atan( fabs( pt1->y() - pt2->y() ) / fabs( pt1->x() - pt2->x() ) )
+             + ( M_PI / 2 );
+    }
+  }
+
+  else /* ( pt1->x() > pt2->x() ) - equality case handled above */
+  {
+    if ( pt1->y() > pt2->y() )
+    {
+      return atan( fabs( pt1->x() - pt2->x() ) / fabs( pt1->y() - pt2->y() ) )
+             + M_PI;
+    }
+    else /* ( pt1->y() < pt2->y() )  - equality case handled above */
+    {
+      return atan( fabs( pt1->y() - pt2->y() ) / fabs( pt1->x() - pt2->x() ) )
+             + ( M_PI + ( M_PI / 2 ) );
+    }
+  }
+
+  return QVariant();
+}
+
 static QVariant fcnRound( const QVariantList& values, const QgsExpressionContext *, QgsExpression* parent )
 {
   if ( values.length() == 2 )
@@ -2700,6 +2771,7 @@ const QList<QgsExpression::Function*>& QgsExpression::Functions()
     << new StaticFunction( "sqrt", 1, fcnSqrt, "Math" )
     << new StaticFunction( "radians", 1, fcnRadians, "Math" )
     << new StaticFunction( "degrees", 1, fcnDegrees, "Math" )
+    << new StaticFunction( "azimuth", 2, fcnAzimuth, "Math" )
     << new StaticFunction( "abs", 1, fcnAbs, "Math" )
     << new StaticFunction( "cos", 1, fcnCos, "Math" )
     << new StaticFunction( "sin", 1, fcnSin, "Math" )

diff --git a/tests/src/core/testqgsexpression.cpp b/tests/src/core/testqgsexpression.cpp
@@ -581,6 +581,8 @@ class TestQgsExpression: public QObject
       QTest::newRow( "relate bad 2" ) << "relate(geom_from_wkt('POINT(110 120)'),geom_from_wkt(''))" << false << QVariant();
       QTest::newRow( "relate pattern true" ) << "relate( geom_from_wkt( 'LINESTRING(40 40,120 120)' ), geom_from_wkt( 'LINESTRING(40 40,60 120)' ), '**1F001**' )" << false << QVariant( true );
       QTest::newRow( "relate pattern false" ) << "relate( geom_from_wkt( 'LINESTRING(40 40,120 120)' ), geom_from_wkt( 'LINESTRING(40 40,60 120)' ), '**1F002**' )" << false << QVariant( false );
+      QTest::newRow( "azimuth" ) << "toint(degrees(azimuth( make_point(25, 45), make_point(75, 100)))*1000000)" << false << QVariant( 42273689 );
+      QTest::newRow( "azimuth" ) << "toint(degrees( azimuth( make_point(75, 100), make_point(25,45) ) )*1000000)" << false << QVariant( 222273689 );
 
       // string functions
       QTest::newRow( "lower" ) << "lower('HeLLo')" << false << QVariant( "hello" );