On recent drivers, double buffered DirectDraw flips no longer wait for the
vertical sync before returning and instead just insert the flip into the
flip queue for later execution. This effectively results in triple buffered
behavior (in the render-ahead sense) and causes up to an extra frame of
latency even if the flip queue size is set to 1.
To restore the legacy double buffered behavior, each flip waits for the
presented frame to leave the flip queue before returning.
To restore the legacy triple buffered behavior, the flip queue size is
forced to 1. This causes the flip to wait if the previous flip is still
pending.
Video memory render target surfaces get an additional video memory off-screen
plain surface used for providing efficient direct memory access (locking).
All 2D operations starting with a lock are redirected to the off-screen plain
surface until the next rendering operation requires the render target surface.
The two surfaces are kept in sync via blits as needed.
Fixes performance issues in Rogue Spear menus, mentioned in issue #2.
Disabled the indication of mirrored blit support via the driver GetCaps routine
as this may be reported as supported on modern GPUs even when it's not.
Removing this indication allows the HEL (Hardware Emulation Layer) to correctly
handle all mirrored blits. It also seems to perform better than the previous
clumsy line-by-line mirroring emulation.
This change assigns a different DirectDraw repository object for each original
DirectDraw object that requires temporary surfaces, ensuring that video memory
surfaces are created on the appropriate device on a multi-GPU system.
