#visualization toolkit

[fruitsoftheweb]

“Streamlines with numbers“

[viva64]

PVS-Studio example N35 (Visualization Toolkit (VTK))

Tags: c++, cpp, cplusplus, pvs-studio, bugs, programming

We have gathered a large collection of errors detected in open-source projects with PVS-Studio. We've decided to pick out and post one sample with an error once a day. It will enable you to see what PVS-Studio is capable of and what funny errors sometimes occur in programs. We believe that will be interesting. Studying these errors, one can work out a safer coding style.

Project name: Visualization Toolkit (VTK)

PVS-Studio: V557 Array overrun is possible. The '6' index is pointing beyond array bound. vtkGraphics vtkcursor2d.cxx 313

void vtkCursor2D::SetModelBounds(double bounds[6]) { this->SetModelBounds(bounds[0], bounds[1], bounds[2], bounds[3], bounds[6], bounds[5]); }

This is what should have been written here: bounds[4].

[mvictoras]

vtkCamera problem with setPosition

While working on a VTK project, I had to change the position of the camera so by looking at the API, I used the setPosition() function.

The problem that I faced that sometimes after changing the position I would get a blank black screen. Update() or Render() or Invalidate() did not work. The only way to “re-render” the window and show something was by interacting with the mouse: A click, or a pan would immediately redraw everything correctly with the vtkCamera in the position that I had set up using setPosition() !

This problem drove me crazy for days and I finally gave up without finding a solution, until yesterday!

So basically when you use the setPosition() of the vtkCamera class in VTK you change the position of the vtkCamera. The clipping range is not changed though, and if it happens that your new camera position is OUTSIDE the clipping range, then you see nothing!! By clicking on the window, you basically slightly change the position of the camera and VTK forces a recalculation of the clipping range based on the new camera position and thus you see the object again! So basically to fix the problem, you have to do is run the ResetCameraClippingRange() on the vtkRenderer object. So for example: theRenderer->GetActiveCamera()->setPosition(0.0, 0.0, 0.0); theRenderer->ResetCameraClippingRange();

Hope this helps!