Someone knows how to implement an effect, such that the edges of a surface patch are highlighted when the patch is under the cursor. I know how to pick the patch, but not sure if I can highlight and de-highlight the edges, which are linestrips, without redraw the whole scene.

-Thanks in advance

If you are depth buffered you need only redraw the object unless there’s transparency involved.

How about the following link, except you have alpha instead of color to highlight only the edges of the object, then to unhilight you simply redraw the object:

Texgen with a spheremap would also be passable on inferior hardware, but would have artifacts that cubemaps solve.

Hmm… you mentioned patch specifically, well you could still use a 1D texture function to map the patch edges. If it isn’t subdivided sufficiently then a 2D function would work, or even multipass on the patch for each edge with a 1D function.