I'm using 2 atlas in same panel, 1 is normal atlas, 1 is grayscale atlas. The problem is each sprite using grayscale atlas cost 2 drawcall, not 1 drawcall for whole atlas.
hierarchy:
UIPanel
- UIGrid
- item1
- background (normal atlas)
- item2
- background (grayscale atlas)
- item3
- background (grayscale atlas)