Problem: Why are there little triangular indents in my 3D streamlines? It looks like something chopped out little pieces.
Solution: Its an issue with your OpenGL driver. The thick streamline (more than one pixel wide) is drawn as a bunch of line segments. Instead of making the ends of one segment overlap with the beginning of the next segment your OpenGL driver just cuts them off horizontally or vertically depending on the segments orientation. If the end of the one segment is cut off horizontally and the beginning of the next is cut off vertically you may end up with missing triangles. Other OpenGL implementations do a much better job of capping the ends of the line segments. If your OpenGL driver had capped the line segments with semi-circles for example it would have looked perfect.The basic work-around is to avoid using thick lines. If you use a stream ribbon or stream rod instead of a 3D volume line it would have had a thickness but would not have had gaps.