Disable opportunistic sprite batching?

[asherkin]

#3060

• Sprite Batching: Collects sprites in a vertex buffer to draw many sprites with a single draw call. Sprites are batched by their Handle<Image> within a specific z-level. When possible, sprites are opportunistically batched across z-levels (when no sprites with a different texture exist between two sprites with the same texture on different z levels).

I've got a 2D scene which interleaves sprites and SVG paths rendered with bevy_prototype_lyon, and I'm running into an insane issue where on approximately 5% of executions, one of the sprites renders with the wrong z-index. I'm fairly sure at this point it is because of the opportunistic across z-level batching, likely as the code in bevy handling that is not accounting for objects drawn by other 2D pipelines.

Is it possible to disable the across z-level batching? Or disable batching entirely? Am I barking up entirely the wrong tree?

Here's a quick video of what I'm seeing, in all cases I'm changing the transform / visibility of the sprite on the top, but it's affecting whether the sprite on the bottom is displayed above or below the rounded rectangle. For reference, in the scene setup before I started fiddling, the top sprite and bottom rectangle are z 1.0, and the top rectangle and bottom sprite are z 2.0. So the sprites should be behind the top rectangle, and above the bottom rectangle.

Screen.Recording.2022-09-08.at.21.49.00.mov

Using bevy 0.8.1 and bevy_prototype_lyon 0.6.0.

[asherkin]

Am I barking up entirely the wrong tree?

Almost. The rendering system is supposed to handle this case correctly (and goes to some lengths to try to), and it's not actually the sprite-specific batching catching me out here. This appears to actually be a bug with handling 2D phase item draw batching lower down the stack. Hopefully #5942 is the solution.