large kernels sometimes take very long to run the first time and sometimes crash the webgl context

[chadams77]

Sometimes I'll be able to refresh multiple times without it happening, other times it will spit out 'webgl context lost' in the console, some of those times it will black screen for a bit, sometimes I need to restart chrome and/or my computer to get it to work again.

It seems to happen when a kernel is first run, i.e. if you change the render kernel in the demo by pressing [R] it may freeze for a while.

It's hard to catch with the profiler, but the one time I caught it if I recall most of the time was spent in glGet(something)Location(some type)

Running the latest stable version of Chrome on Windows 10 with a 6GB GTX 1060

Example: https://chadams77.github.io/cs-SSPS/
Source: https://github.com/chadams77/cs-SSPS/blob/master/scripts/ssps.js

[chadams77]

The time it takes to run these shaders the first time seems to be proportional to the maximum number of loop iterations inside the shader. Perhaps this is something specific to my driver?

[robertleeplummerjr]

@chadams77 You may be on to something. Did you ever uncover anything else?

[chadams77]

@robertleeplummerjr I believe it's an issue with the browser's graphics engine involving automatically unrolling loops, it might be fixable if gpu.js had an automatic loop unrolling option. Although it's not 100%, this issue only comes up when there's more than 100 or so iterations in a shader/kernel. It could be that unrolling creates a huge shader and so makes the shader compile time just as long as if the driver unrolled the loops. Maybe there's some way to tell WebGL not to unroll loops via is setting or something?

[robertleeplummerjr]

Should have this partially resolved in the commit 05dd174. I'll try and see about getting it released in the next day or two. You are welcome to download the included browser file and test if it resolved the issue.