Hillshaderenderer: Fix calculation of aspect (#3152)

Author: AsgerPetersen

src/core/raster/qgshillshaderenderer.cpp

@@ -103,7 +103,6 @@ QgsRasterBlock *QgsHillshadeRenderer::block( int bandNo, const QgsRectangle &ext
   double cellYSize = extent.height() / double( height );
   double zenithRad = qMax( 0.0, 90 - mLightAngle ) * M_PI / 180.0;
   double azimuthRad = -1 * mLightAzimuth * M_PI / 180.0;
-  double aspectRad = 0;
   double cosZenithRad = cos( zenithRad );
   double sinZenithRad = sin( zenithRad );
 
@@ -121,12 +120,6 @@ QgsRasterBlock *QgsHillshadeRenderer::block( int bandNo, const QgsRectangle &ext
         continue;
       }
 
-      if ( inputBlock->isNoData( i, j ) )
-      {
-        outputBlock->setColor( i, j, myDefaultColor );
-        continue;
-      }
-
       qgssize iUp, iDown, jLeft, jRight;
       if ( i == 0 )
       {
@@ -189,26 +182,7 @@ QgsRasterBlock *QgsHillshadeRenderer::block( int bandNo, const QgsRectangle &ext
       double derY = calcFirstDerY( x11, x21, x31, x12, x22, x32, x13, x23, x33, cellYSize );
 
       double slope_rad = atan( mZFactor * sqrt( derX * derX + derY * derY ) );
-
-      if ( derX != 0 )
-      {
-        aspectRad = atan2( derX, -derY );
-        if ( aspectRad < 0 )
-        {
-          aspectRad = 2 * M_PI + aspectRad;
-        }
-      }
-      else if ( derX == 0 )
-      {
-        if ( derY > 0 )
-        {
-          aspectRad = M_PI_2;
-        }
-        else if ( derY < 0 )
-        {
-          aspectRad = 2 * M_PI - M_PI_2;
-        }
-      }
+      double aspectRad = atan2( derX, -derY );
 
       double colorvalue = qBound( 0.0, 255.0 * (( cosZenithRad * cos( slope_rad ) ) +
                                   ( sinZenithRad * sin( slope_rad ) *
@@ -250,9 +224,8 @@ double QgsHillshadeRenderer::calcFirstDerX( double x11, double x21, double x31,
 
 double QgsHillshadeRenderer::calcFirstDerY( double x11, double x21, double x31, double x12, double x22, double x32, double x13, double x23, double x33, double cellsize )
 {
-  Q_UNUSED( x22 );
-  Q_UNUSED( x32 );
   Q_UNUSED( x21 );
+  Q_UNUSED( x22 );
   Q_UNUSED( x23 );
   return (( x31 + x32 + x32 + x33 ) - ( x11 + x12 + x12 + x13 ) ) / ( 8 * -cellsize );
 }