[vtk-developers] 2D Clipping Planes

[Ken Martin]

>Incidentally....OpenGL behaves a little strangely when clipping images. If 
>the left/bottom pixel is just outside the clipping region, it clips the 
>whole image away, when in fact I'd like it to just clip the few pixels 
>which are outside the region. I've got around this in my code by adding a 
>whole series of tests which then set the render-rectangle and allow 
>sub-regions to be rendered, but its messy and not ideal for general use. 
>Has anyone come across this and found a "pure opengl" solution.

Another possibility is vtkImageActor which uses texture mapping which we 
have found in many cases to be much faster than the drawpixels call. It has 
some good and bad points but it might be a cleaner way to display clipped 
images than the sub-regions you are discussing above.

- Ken