Intended to replace legacy GL_SELECT, without the limitations of
sample queries which can't access depth information.
This commit adds VIEW3D_SELECT_PICK_NEAREST and VIEW3D_SELECT_PICK_ALL
which access the depth buffers to detect whats under the pointer,
so initial selection is always the closest item.
The performance of this method depends a lot on the OpenGL
implementations glReadPixels.
Since reading depth can be slow, buffers are cached for object picking
so selecting re-uses depth data, performing 1 draw instead of 3
(for 24, 18, 10 px regions, picking with many items under the pointer).
Occlusion queries draw twice when picking nearest,
so worst case 6x draw calls per selection.
Even with these improvements occlusion queries is faster on AMD hardware.
Depth selection is disabled by default, toggle option under select method.
May enable by default if this works well on different hardware.
Reviewed as D2543
This patch creates an interface for selection mechanisms in opengl. This
makes it possible to switch between occlusion query based or select
rendermode based selection transparently.
This is really useful on graphics drivers that do not accelerate the
select rendermode path (some ATI cards are notorious for this, and the
new path is used by default there), since occlusion queries are always
hardware accelerated due to their use in games.
The option can be found under system - selection. Auto just enables
occlusion queries for ATI users while the rest of the options enforce
one of the two methods always.
There is just one known change, previous code enforced nearest bone to
always get selected, even when mouse selecting near the same position, I
couldn't replicate the behaviour though.
patch by me with edits and review by Campbell.
Thanks!
