EgtGraphics :

- migliorato calcolo centro di vista in Zwin utilizzando GetPixelZ.

Scene.h

@@ -246,6 +246,7 @@ class Scene : public IEGrScene
       bool MyDraw( bool bSwapBF) ;
       bool Background( void) ;
       bool Prepare( void) ;
+      bool GetPixelZ( const Point3d& ptWin, double& dWinZ) ;
      // Camera
       bool VerifyCamera( bool bUseOrizzOffsCamera = false) ;
       bool CalcDirUp( bool bUseOrizzOffsCamera = false) ;

SceneBasic.cpp

@@ -941,6 +941,24 @@ Scene::UnProject( const Point3d& ptView, Point3d& ptWorld) const
    return ( nRes == GL_TRUE) ;
 }
 
+//----------------------------------------------------------------------------
+bool
+Scene::GetPixelZ( const Point3d& ptWin, double& dWinZ)
+{
+   glGetError() ;
+   GLint Viewport[ 4] ;
+   glGetIntegerv( GL_VIEWPORT, Viewport) ;
+   float dZ ;
+   glReadBuffer( GL_FRONT) ;
+   glReadPixels( int( ptWin.x), Viewport[3] - int( ptWin.y), 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &dZ) ;
+   if ( glGetError() == GL_NO_ERROR  &&  dZ > 0.001  &&  dZ < 0.999) {
+      dWinZ = dZ ;
+      return true ;
+   }
+   dWinZ = GetProjectedCenter().z ;
+   return false ;
+}
+
 //----------------------------------------------------------------------------
 void
 Scene::Destroy( void)

SceneCamera.cpp

@@ -525,8 +525,12 @@ Scene::ZoomChange( double dCoeff)
 bool
 Scene::ZoomOnPoint( const Point3d& ptWin, double dCoeff)
 {
+  // leggo Z del pixel
+   double dWinZ ;
+   GetPixelZ( ptWin, dWinZ) ;
+
   // porto il punto in coordinate mondo
-   Point3d ptView( ptWin.x, ptWin.y, GetProjectedCenter().z) ;
+   Point3d ptView( ptWin.x, ptWin.y, dWinZ) ;
    Point3d ptWorld ;
    if ( ! UnProject( ptView, ptWorld))
       return false ;