Item in gui atlas draw eats too much video memory

Each draw for item in gui atlas will acquire a pair of staging buffer and vertex buffer, with 256kb minimum size for each. If there is too much item to draw on atlas, the game will acquire tons of staging buffer and vertex buffer, eating lots of video memory. With 81 unique enchanted items (54 in chest, 27 in inventory) that need to be drawn in every frame, we can see significant vram increase when open the chest.

Those draw can share the same staging and vertex buffer, and there might be even no need to use staging buffer at all when drawing item to item in gui atlas as we do not need upload data to multiple gpu buffers here.