One of the longest-running issues with Leveller's display has been
resolved for 2.6: there is now an option to fully buffer the OpenGL
output in the 3D scene pane to completely avoid artifacting problems
when one makes another app active and overlaps Leveller's window with
it. The pixel ownership issue is solved by making the render target an
offscreen bitmap, thus OpenGL draws everything it is asked to. You can
hit F5, switch to another app, clobber the Lev window, and when the
render is finished, Lev won't have anything missing.
There is a catch: I don't know of any video cards that do hardware
acceleration for offscreen GL. Worse, depending on the OpenGL
implementation, small pixel artifacts may appear sprinkled in the image.
My guess is that on Windows, the OS switches to its own software
renderer when offscreen OpenGL is requested, and it isn't as good as
hardware versions from nVidia, etc.
The speed difference is of course noticeable; on my 1.6Ghz box the
buffered drawing was on average about 50% of normal. This may sound not
too bad but only because Lev is atypical in drawing lots of small
triangles where a game normally draws fewer and bigger tris. The
buffering option will therefore likely be extended with a "Don't buffer
for documents above X pixels" setting. But if you have a card that
supports accelerated offscreening, Lev 2.6 will take advantage of it.
Ray
