Problem running on mobile platforms

[dav1dsm1th]

The behaviour of the water is different when running on mobile hardware compared to what is seen on desktop h/w.

On desktop, the movement of the water is dampened over time and relatively quickly returns to a smooth surface.

On both ios and android the surface appears to be perturbed by additional velocities which stop the water from ever settling back to a smooth state.

One obvious difference is that the pixel ratio, when run on the desktop h/w, is 1.0 but on the mobile h/w it varies (on the examples I have tried it on) - 2.0 on an iPhone and 2.75 on an Android. Not sure if this is related - but it struck me that the "averaging of neighbour pixels" may be looking "further away" than expected and picking a velocity that is higher than an immediate neighbour - causing the wrong average to be calculated. But that's a wild stab in the dark.

I'm struggling to debug the shaders - to compare the actual calculated values on the different h/w - but I'll continue trying...

Any thoughts/fixes would be appreciated.

[dav1dsm1th]

I looked into the pixel ratio and it doesn't get passed to the shaders - so that's a red herring.

It's as if the precision of the storage of a float is lower on mobile.

I found https://developer.mozilla.org/en-US/docs/Web/API/WebGL_API/WebGL_best_practices

Which makes reference to issues with highp - which hints that precision may be different on mobile. I'll keep stumbling around for now.