Toon shader (and others) cause error on mobile devices

Problem Description

____ A concise description of your problem here ____

When using toon shader and possibly others, you get an error that highp is not supported for fragment shader on some mobile devices. See here: http://updates.html5rocks.com/2011/12/U ... n-possible. This will cause mobile chrome to give an error and not load the game, though other browsers like firefox seem to load it but perhaps ignore the shader.

Can you describe which devices and with which browsers specifically? I'd have thought the browser engine would just substitute a working precision instead.

I have since stopped using the toon shader (I only use shaders to mockup stuff that I later put directly into the art), but I can run some tests and figure it out, I think the browser was definitely a version of Chrome, and the device may have been the HTC One X on Sprint but I'm less sure on the device.

Relates to this maybe:

https://code.google.com/p/chromium/issu ... ?id=245755

essentially sounds like a bug in the drivers that allows chrome to detect available precision correctly, or maybe some other problem causing Chrome's detection to fail.

I think I found a workaround based on checking if GL_FRAGMENT_PRECISION_HIGH is defined in the shader and falling back to mediump instead. I've made the change for the next build but don't have any affected devices to test on - could you let me know if it's fixed when r164 is out?

Ok, will do.

This is now fixed on my device. Also I guess maybe having medium precision shaders as an option could be good for performance?