Android example very slow running on device following light transmission changes

[fudini]

The commit 44928e0 makes mobile example run on android device at ~1 FPS (~20 before).

To reproduce:

cargo apk run -p bevy_mobile_example

[alice-i-cecile]

@coreh @superdump any ideas?

[cart]

Hmm my money is on the shader code, given that we don't run the transmission pass without transmissive materials. Maybe try commenting out the relevant branches/code blocks in pbr_functions.wgsl?

ex: if diffuse_transmission > 0.0 {

[fudini]

Commenting out suggested by @cart shader code makes it run faster but not as fast as before.
I measured with diagnostic plugins and got this:
Before: 14 FPS
After: 2 FPS
Without shader code: 10 FPS

[cart]

but not as fast as before.

For clarity: did you test the commit right before the Transmission commit?

[fudini]

but not as fast as before.

For clarity: did you test the commit right before the Transmission commit?

Yes, d67fbd5

[cart]

So one quick (partial) fix would be to put all of that code behind a "shader def", which we set whenever diffuse transmission is above 0.0.