Instead of creating a new instancing shading group without attrib, we now have instancing calls. The benefits is that they can be culled.
They can be used in conjuction with the standard and generate calls but shader must support it (which is generally not the case).
We store a pointer to the actual count so that the number can be tweaked between redraw.
This will makes multi layer rendering more efficient.
This is very efficient and add a pretty low overhead (0.1ms of drawing time for 10K objects passing through all tests, on my i3-4100M).
The like the rest of the DRWCallState, test is "cached" until the view matrices changes.
Refactor include:
- Removal of DRWInterface. (was useless)
- Split DRWCallHeader into a new struct DRWCallState that will be reused in the future.
- Use BLI_link_utils for APPEND/PREPEND.
- Creation of the new DRWManager struct type. This will enable us to create more than one manager in the future.
- Removal of some dead code.
